HomeMy WebLinkAbout2026-03-18; Planning Commission; Resolution 7570PLANNING COMMISSION RESOLUTION NO. 7570
A RESOLUTION OF THE PLANNING COMMISSION OF THE CITY OF
CARLSBAD, CALIFORNIA, RECOMMENDING APPROVAL OF
ADDENDUM NO. 1 TO THE CITY OF CARLSBAD DRAINAGE MASTER PLAN
FINAL EIR STATE CLEARINGHOUSE NO. 2006041066 (EIR 04-02), FOR A
LOCAL COASTAL PROGRAM AMENDMENT TO REPLACE REFERENCES TO
THE MASTER DRAINAGE PLAN ADOPTED IN 1994 AND THE 2008
DRAINAGE MASTER PLAN WITH REFERENCES TO THE 2026 DRAINAGE
MASTER PLAN
CASE NAME: 2026 DRAINAGE MASTER PLAN
CASE NO.: LCPA2025-0024 (PUB2022-0009)
WHEREAS, the City of Carlsbad, in accordance with Section 21.52.020 of the Carlsbad Municipal
Code, has prepared a proposed a Local Coastal Program Amendment relating to references to the 2008
Drainage Master Plan; and
WHEREAS, pursuant to the California Environmental Quality Act (CEQA, Public Resources
Code section 21000 et seq.) and its implementing regulations (the State CEQA Guidelines, Article 14 of
the California Code of Regulations section 15000 et seq.), the city is the Lead Agency for the project, as
the public agency with the principal responsibility for approving the proposed project; and
WHEREAS, an Environmental Impact Report (EIR), State Clearinghouse No. 2006041066 (EIR 04-
02) was prepared and the City Council adopted Resolution 2008-229, certifying EIR 04-02 as complete on
Aug. 5, 2008 for the City of Carlsbad Drainage Master Plan; and
WHEREAS, an EIR Addendum was developed to evaluate the request for a Local Coastal Program
Amendment as shown on Attachment A and to determine whether the environmental effects of
subsequent activity are within the scope of the previously prepared EIR; and
WHEREAS, pursuant to CEQA, when taking subsequent discretionary actions in furtherance of a
project for which an EIR has been certified, the Lead Agency is required to review any changed
circumstances to determine whether any of the circumstances under Public Resources Code section
21166 and CEQA Guidelines section 15162 require additional environmental review; and
WHEREAS, City staff evaluated the details of the request, which included the Local Coastal
Program Amendment and the environmental changes caused by the project for subsequent
environmental review outlined in Public Resources section 21166 and CEQA Guidelines section 15162;
and
WHEREAS, based on this evaluation, staff concluded that the EIR had fully analyzed and mitigated,
where feasible, in compliance with CEQA, all potentially significant environmental impacts, if any, that
would result from the details of the request, that the impacts to the environment as a result of the
modifications are consistent with and would not create substantial new or increased impacts beyond
those that were evaluated in the EIR, and that, therefore, no subsequent EIR or mitigated negative
declaration is now required; and
WHEREAS, the Planning Commission did, on March 18, 2026, hold a duly noticed public hearing
as prescribed by law to consider said request; and
WHEREAS, at said public hearing, upon hearing and considering all testimony and arguments, if
any, of all persons desiring to be heard, said Commission considered all factors relating to the Local Coastal
Program Amendment; and
NOW, THEREFORE, BE IT RESOLVED by the Planning Commission of the City of Carlsbad as follows:
1. That the foregoing recitations are true and correct.
2. Record and Basis for Action. The Planning Commission has considered the full record before
it, which includes the Record of Proceedings. Furthermore, the recitals set forth above are
found to be complete, true, accurate, and material to this resolution; and are incorporated
herein by reference.
3. State CEQA Guidelines section 15164 requires lead agencies to prepare an Addendum to a
previously certified EIR if some changes or additions to the project are necessary, but none of
the conditions requiring preparation of a subsequent EIR are present. The Planning
Commission has reviewed and considered the EIR and Addendum and finds that those
documents taken together contain a complete and accurate reporting of all of the
environmental impacts associated with the revised project. The Planning Commission further
finds that the Addendum and administrative record have been completed in compliance with
CEQA and CEQA Guidelines, and that the findings related to the EIR and Addendum, taken
together, reflect the Planning Commission's independent judgment. Based upon the evidence
submitted and as demonstrated by the analysis included in the Addendum, which is
Attachment A, none of the conditions described in CEQA Guidelines sections 15162 calling for
the preparation of a subsequent or supplemental EIR or negative declaration have occurred;
specifically:
a. The proposed modifications to the project do not create substantial changes that
would
require major revisions to the EIR due to the involvement of new significant
environmental effects or a substantial increase in the severity of previously identified
significant effects; and
b. The proposed modifications to the project do not create substantial changes with
respect to the circumstances under which the project is undertaken that will require
major revisions of the previous EIR due to the involvement of new significant
environmental effects or a substantial increase in the severity of previously identified
significant effects; and
c. There is no new information of substantial importance, which was not known and
could not have been known with the exercise of reasonable diligence at the time the
EIR was certified as complete and adopted, that shows any of the following:
i. The modifications will have one or more significant effects not discussed in
the certified EIR;
ii. Significant effect previously examined will be substantially more severe than
shown in the certified EIR;
iii. Mitigation measures or alternatives previously found not to be feasible would
in fact be feasible and would substantially reduce one or more significant
effects of the project, but the Applicant declines to adopt the mitigation
measure or alternative; or
iv. Mitigation measures or alternatives that are considerably different from
those analyzed in the certified EIR would substantially reduce one or more
significant effects on the environment, but the Applicant declines to adopt
the mitigation measure or alternative; and
v. The evaluation of the proposed modifications to the project, certified EIR, and
Addendum reflects the Planning Commission's independent judgment and
analysis based on the Planning Commission's review of the entirety of the
administrative record, which record provides the information upon which this
resolution is based.
d. Pursuant to the above findings, the Planning Commission determines that the EIR,
together with the Addendum, satisfy all the requirements of CEQA and is adequate
to serve as the required environmental documentation for the project and, therefore,
hereby recommends that the City Council approve and adopt the Addendum for the
project.
e. The custodian of the documents and other materials which constitute the record of
proceedings upon which this decision is based is the Office of the City Clerk of the City
of Carlsbad, 1200 Village Drive, Carlsbad, CA 92008.
4. That based on the evidence presented at the public hearing, the Planning Commission
RECOMMENDS APPROVAL of an Addendum to Environmental Impact Report EIR 04-02, after
considering the addendum with the final EIR, based on the findings above.
NOTICE
Please take NOTICE that approval of your project includes the “imposition” of fees, dedications,
reservations, or other exactions hereafter collectively referred to for convenience as “fees/exactions.”
You have 90 days from date of final approval to protest imposition of these fees/exactions. If you protest
them, you must follow the protest procedure set forth in Government Code §66020(a) and file the protest
and any other required information with the City Manager for processing in accordance with Carlsbad
Municipal Code Section 3.32.030. Failure to timely follow that procedure will bar any subsequent legal
action to attack, review, set aside, void, or annul their imposition.
You are hereby FURTHER NOTIFIED that your right to protest the specified fees/exactions DOES NOT
APPLY to water and sewer connection fees and capacity charges, nor planning, zoning, grading, or other
similar application processing or service fees in connection with this project; NOR DOES IT APPLY to any
fees/exactions of which you have previously been given a NOTICE similar to this, or as to which the statute
of limitations has previously otherwise expired.
PASSED, APPROVED, AND ADOPTED at a regular meeting of the Planning Commission of
the City of Carlsbad, California, held on March 18, 2026, by the following vote, to wit:
AYES: Hubinger, Merz, Lafferty, Fitzgerald, Burrows, Foster, Meenes.
NAYES: None.
ABSENT: None.
ABSTAIN: None.
___________________________________
ROY MEENES, Chairperson
Carlsbad Planning Commission
ATTEST:
___________________________________
ERIC LARDY, Assistant Director
of Community Development
January 2026
ADDENDUM TO THE
FINAL ENVIRONMENTAL IMPACT REPORT
CITY OF CARLSBAD DRAINAGE MASTER PLAN UPDATE
EIR #04-02, DATED DECEMBER 2007, APPROVED AUGUST 2008 /
STATE CLEARINGHOUSE NO. 2006041066
CITY OF CARLSBAD
SAN DIEGO COUNTY, CALIFORNIA
Submitted to:
City of Carlsbad
1635 Faraday Avenue
Carlsbad, California 92008
Prepared by:
LSA Associates, Inc.
703 Palomar Airport Road, Suite 280
Carlsbad, California 92011
(760) 931-5471
LSA Project No. RKE2001
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Carlsbad
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TABLE OF CONTENTS
EXECUTIVE SUMMARY ........................................................................................................................ ES-i
EXHIBITS, FIGURES, AND TABLES ........................................................................................................... iii
1.0 INTRODUCTION ................................................................................................ 1-1
1.1 Contact Person and Phone Number ................................................................................. 1-1
1.2 Project Location ................................................................................................................ 1-1
1.3 Project Sponsor’s Name and Address ............................................................................... 1-1
1.4 Background and Project Context .................................................................................... 1-13
1.4.1 2008 DMP Update ........................................................................................................... 1-13
1.4.2 Project Changes ............................................................................................................... 1-14
1.5 Overview of CEQA Guidelines ......................................................................................... 1-15
1.6 Findings of this Addendum ............................................................................................. 1-17
1.7 Location of Prior Environmental Document ................................................................... 1-18
2.0 PROJECT DESCRIPTION ...................................................................................... 2-1
2.1 Project Components ......................................................................................................... 2-1
2.1.1 Updates to Local Regulations ............................................................................................ 2-6
3.0 ENVIRONMENTAL ANALYSIS ............................................................................. 3-1
3.1 Findings of the 2008 DMP Update EIR .............................................................................. 3-1
3.2 Addendum Methodology.................................................................................................. 3-1
3.3 Land Use ........................................................................................................................... 3-3
3.3.1 Previous Analysis ............................................................................................................... 3-3
3.3.2 Analysis of the Project Changes ......................................................................................... 3-3
3.3.3 Substantial Changes with Respect to Circumstances or New Information of
Substantial Importance .................................................................................................... 3-11
3.3.4 Conclusion ....................................................................................................................... 3-13
3.4 Agricultural Resources .................................................................................................... 3-13
3.4.1 Previous Analysis ............................................................................................................. 3-13
3.4.2 Analysis of the Project Changes ....................................................................................... 3-14
3.4.3 Substantial Changes with Respect to Circumstances or New Information of
Substantial Importance .................................................................................................... 3-17
3.4.4 Conclusion ....................................................................................................................... 3-17
3.5 Visual Resources ............................................................................................................. 3-18
3.5.1 Previous Analysis ............................................................................................................. 3-18
3.5.2 Analysis of the Project Changes ....................................................................................... 3-18
3.5.3 Substantial Changes with Respect to Circumstances or New Information of
Substantial Importance .................................................................................................... 3-20
3.5.4 Conclusion ....................................................................................................................... 3-21
3.6 Transportation/Circulation ............................................................................................. 3-21
3.6.1 Previous Analysis ............................................................................................................. 3-21
3.6.2 Analysis of the Project Changes ....................................................................................... 3-22
3.6.3 Substantial Changes with Respect to Circumstances or New Information of
Substantial Importance .................................................................................................... 3-23
3.6.4 Conclusion ....................................................................................................................... 3-24
3.7 Air Quality ....................................................................................................................... 3-24
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CIP Project No. 6623
Addendum ii January 2026
3.7.1 Previous Analysis ............................................................................................................. 3-24
3.7.2 Analysis of the Project Changes ....................................................................................... 3-25
3.7.3 Substantial Changes with Respect to Circumstances or New Information of
Substantial Importance .................................................................................................... 3-29
3.7.4 Conclusion ....................................................................................................................... 3-30
3.8 Noise ............................................................................................................................... 3-30
3.8.1 Previous Analysis ............................................................................................................. 3-30
3.8.2 Analysis of the Project Changes ....................................................................................... 3-31
3.8.3 Substantial Changes with Respect to Circumstances or New Information of
Substantial Importance .................................................................................................... 3-35
3.8.4 Conclusion ....................................................................................................................... 3-36
3.9 Recreation ....................................................................................................................... 3-37
3.9.1 Previous Analysis ............................................................................................................. 3-37
3.9.2 Analysis of the Project Changes ....................................................................................... 3-37
3.9.3 Substantial Changes with Respect to Circumstances or New Information of
Substantial Importance .................................................................................................... 3-38
3.9.4 Conclusion ....................................................................................................................... 3-38
3.10 Geology/Soils .................................................................................................................. 3-39
3.10.1 Previous Analysis ............................................................................................................. 3-39
3.10.2 Analysis of the Project Changes ....................................................................................... 3-39
3.10.3 Substantial Changes with Respect to Circumstances or New Information of
Substantial Importance .................................................................................................... 3-40
3.10.4 Conclusion ....................................................................................................................... 3-40
3.11 Hydrology/Water Quality ............................................................................................... 3-41
3.11.1 Previous Analysis ............................................................................................................. 3-41
3.11.2 Analysis of the Project Changes ....................................................................................... 3-41
3.11.3 Substantial Changes with Respect to Circumstances or New Information of
Substantial Importance .................................................................................................... 3-43
3.11.4 Conclusion ....................................................................................................................... 3-43
3.12 Biological Resources ....................................................................................................... 3-44
3.12.1 Previous Analysis ............................................................................................................. 3-44
3.12.2 Analysis of the Project Changes ....................................................................................... 3-45
3.12.3 Substantial Changes with Respect to Circumstances or New Information of
Substantial Importance .................................................................................................... 3-48
3.12.4 Conclusion ....................................................................................................................... 3-48
3.13 Cultural Resources .......................................................................................................... 3-49
3.13.1 Previous Analysis ............................................................................................................. 3-49
3.13.2 Analysis of the Project Changes ....................................................................................... 3-49
3.13.3 Substantial Changes with Respect to Circumstances or New Information of
Substantial Importance .................................................................................................... 3-53
3.13.4 Conclusion ....................................................................................................................... 3-54
3.14 Paleontological Resources .............................................................................................. 3-54
3.14.1 Previous Analysis ............................................................................................................. 3-54
3.14.2 Analysis of the Project Changes ....................................................................................... 3-55
3.14.3 Substantial Changes with Respect to Circumstances or New Information of
Substantial Importance .................................................................................................... 3-57
3.14.4 Conclusion ....................................................................................................................... 3-57
4.0 REFERENCES ..................................................................................................... 4-1
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January 2026 -iii- Addendum
EXHIBITS, FIGURES, AND TABLES
EXHIBIT
Exhibit 1: Major Watersheds/Basins A–D ........................................................................................... 1-3
FIGURE
Figure 1: Project Location ................................................................................................................... 1-5
TABLES
Table A: Summary of New Proposed DMP Update PLDA Project Components ................................. 2-2
Table B: Summary of Revised 2008 DMP Update PLDA Project Components.................................... 2-3
Table C: Summary of Potential Land Use Impacts of the New or Revised Project Components ....... 3-5
Table D: Potential Impacts to Agricultural Resources from New or Revised Project Components .. 3-15
Table E: Summary of the Visual Changes of the New or Revised Project Components ................... 3-19
Table F: Attainment Status of Criteria Pollutants in San Diego County ............................................ 3-26
Table G: Ambient Air Quality Summary in the Project Vicinity ........................................................ 3-27
Table H: Typical Construction Equipment Noise Levels (dBA) .......................................................... 3-32
Table I: Representative Vibration Source Levels for Typical Construction Equipment .................... 3-34
Table J: Construction Vibration Damage Criteria .............................................................................. 3-34
Table K: Impacts Related to Floodplains and Drainage Channels ..................................................... 3-42
Table L: Additional Sensitive Plant and Wildlife Species Found in Carlsbad, by Basin ..................... 3-46
Table M: Additional Sensitive Plant Species, by General Habitat Type ............................................ 3-46
Table N: Impacts to Vegetation Types from PLDA Project Components .......................................... 3-46
Table O: New or Revised Project Components Within or Adjacent to Cultural Resources Areas .... 3-51
Table P: Cultural Resources Survey and Monitoring Requirements for New or Revised Project
Components ............................................................................................................................. 3-52
Table Q: Paleontological Sensitivity at New or Revised Project Components .................................. 3-55
APPENDICES
A: DMP COMPONENT PROJECT SHEETS
B: EXCERPTS FROM THE 2008 DMP UPDATE EIR
C: PROJECT FEATURES/METHODS/REQUIREMENTS AND MITIGATION MEASURES FROM THE 2008 DMP
UPDATE EIR
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Addendum iv January 2026
LIST OF ABBREVIATIONS AND ACRONYMS
2008 DMP Update Carlsbad Drainage Master Plan Update
AAQS Ambient Air Quality Standards
ADT average daily trips
BMP Best Management Practice
Caltrans California Department of Transportation
CARB State of California Air Resources Board
CDFG California Department of Fish and Game (now California
Department of Fish and Wildlife)
CDFW California Department of Fish and Wildlife (formerly California
Department of Fish and Game)
CEQA California Environmental Quality Act
CIP Capital Improvement Project
City City of Carlsbad
CO carbon monoxide
CRHR California Register of Historical Resources
CWA (Federal) Clean Water Act
CZ Coastal Zone
dBA A-weighted decibel
DMP Drainage Master Plan
DPR Department of Parks and Recreation
EIR Environmental Impact Report
FEMA Federal Emergency Management Agency
FMMP Farmland Mapping and Monitoring Program
FTA Federal Transit Administration
GMP Growth Management Plan
GPS global positioning system
HAA Housing Accountability Act
HCA Housing Crisis Act of 2019
HMP Habitat Management Plan
I-5 Interstate 5
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January 2026 -v- Addendum
in/sec inches per second
LCP Local Coastal Program
LCPA Local Coastal Program Amendment
Leq equivalent noise level
LF linear feet
LOS level of service
MHCP Multiple Habitat Conservation Program
MMRP Mitigation Monitoring and Reporting Program
NAAQS National Ambient Air Quality Standards
NO2 nitrogen dioxide
NPDES National Pollutant Discharge Elimination System
NRHP National Register of Historic Places
O3 ozone
OPR Governor’s Office of Planning and Research
Pb lead
PD Planning Director
PI Principal Investigator
PLDA Planned Local Drainage Area
PM particulate matter
PM10 respirable particulate matter
PM2.5 fine particulate matter
PPV peak particle velocity
RAQS (San Diego) Regional Air Quality Strategy
RCP reinforced concrete pipe
ROW right-of-way
SANDAG San Diego Association of Governments
SCH State Clearinghouse
SCIC South Coastal Information Center
SDAB San Diego Air Basin
SDAPCD San Diego County Air Pollution Control District
SIP State Implementation Plan
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Addendum vi January 2026
SO2 sulfur dioxide
SR-78 State Route 78
STP shovel test pit
SWPPP Storm Water Pollution Prevention Plan
Technical Advisory OPR’s Technical Advisory on Evaluating Transportation Impacts In
CEQA
USACE United States Army Corps of Engineers
USEPA United States Environmental Protection Agency
USFWS United States Fish and Wildlife Service
VMT vehicle miles traveled
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
January 2026 ES-1 Addendum
EXECUTIVE SUMMARY
The 2008 Drainage Master Plan (DMP) Update was a comprehensive planning document for the City of
Carlsbad (City) that served to assess existing storm drain infrastructure and drainage areas, identify
anticipated improvements and infrastructure required to prevent flooding and accommodate storm
flows, and provide guidance on developing a Planned Local Drainage Area (PLDA) fee program to
facilitate construction of specific drainage facilities. The 2008 DMP Update included non-PLDA projects,
including Capital Improvement Projects (CIPs) that involve improvements to existing drainage facilities,
as well as operation and maintenance-related activities for both PLDA and non-PLDA projects. The 2008
DMP Update was the subject of an Environmental Impact Report (EIR) certified by the City in 2008 (State
Clearinghouse [SCH] No. 2006041066) (2008 DMP Update EIR) in accordance with the California
Environmental Quality Act (California Public Resources Code Section 21000 et seq.) (CEQA). Most of
these projects were considered at a programmatic level in the 2008 DMP Update EIR. However, some
components were at a point in the design process that enabled a project-level analysis.
Beginning in 2019, the City of Carlsbad undertook an update of the DMP (referred to herein as the
proposed DMP Update) (Rick Engineering 2025) to identify and prioritize drainage CIPs for the City.
Ultimately, 11 PLDA project components were identified as the most critical to address current storm
drain conveyance deficiencies. This prioritization considered the effects of future development activity
in the City. The 11 project components are a combination of revised projects previously identified in the
2008 DMP Update as well as new projects that are of a substantially similar nature to those that were
previously evaluated.
This Addendum addresses all the New or Revised Project Components, which include several that fall
within the category of potential future DMP components envisioned in the 2008 DMP Update EIR. Given
the limited design information available for the New or Revised Project Components, a programmatic
level of analysis of impacts remains appropriate. This Addendum evaluates minor amendments to City
regulations and ordinances, such as the City Municipal Code (including the Zoning Ordinance), and Local
Coastal Program Land Use Plan, that may be required to revise references to the 2008 DMP Update to
reflect the proposed DMP Update. Updates to the Local Coastal Program Land Use Plan would require
approval from the California Coastal Commission.
In considering the potential environmental impacts of the New or Revised Project Components, the City
has determined that the certified 2008 Update EIR is of continuing informational value. All of the impact
issues previously examined in the 2008 DMP Update EIR remain unchanged with the proposed
modifications. The changes proposed are relatively minor and would not result in any new significant
impacts or result in a substantial increase in the severity of any previously identified significant effects,
which would require the preparation of a subsequent EIR. Based on this, the City has determined that
the potential environmental impacts (both direct and indirect) are within the scope of the previously
certified CEQA document, and that none of the conditions required subsequent or supplemental
environmental review under Section 15162 of the State CEQA Guidelines (California Code of Regulations
Section 15000 et seq.) exists.
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1.0 INTRODUCTION
This document is an Addendum to the Final Environmental Impact Report (EIR) for the City of Carlsbad
Drainage Master Plan (DMP) Update, EIR #04-02, dated December 11, 2007, State Clearinghouse (SCH)
No. 2006041066 (2008 DMP Update EIR). The City of Carlsbad (City) is the lead agency pursuant to the
California Environmental Quality Act (CEQA). On August 5, 2008, the City Council certified the Final EIR,
adopted the Mitigation Monitoring and Reporting Program (MMRP), and approved the Carlsbad
Drainage Master Plan Update (2008 DMP Update).
1.1 CONTACT PERSON AND PHONE NUMBER
Questions regarding preparation of this Addendum, its assumptions, or its conclusions should be
referred to David Edwards at (441) 339-5286 or David.Edwards@carlsbadca.gov.
1.2 PROJECT LOCATION
The New or Revised Project Components to the 2008 DMP Update would occur within the City’s
jurisdictional boundaries, located in the northern portion of San Diego County, California. While the
coastal portions of the 42-square-mile city are largely developed, natural vegetation communities
remain in and around the three coastal lagoons within the city (Buena Vista, Agua Hedionda, and
Batiquitos) and on some of the higher, steep-sloped, inland portions of Carlsbad. Major roadways in the
city include Interstate 5 (I-5) and State Route 78 (SR-78), which provide interregional access through or
around the city. Approximately 14.4 square miles of the City’s land area is located within the California
Coastal Zone. Carlsbad encompasses four local watersheds: Buena Vista Creek, Agua Hedionda Creek,
Encinas Creek, and San Marcos Creek.
The four local watersheds, Buena Vista Creek, Agua Hedionda Creek, Encinas Creek, and San Marcos
Creek, roughly correspond to the four major basins (Basins A, B, C, and D) defined within the 2008 DMP
Update, which are depicted in Figure 1-2 of the 2008 DMP Update EIR (page 1-3) and Exhibit 1, provided
below. The 2008 DMP Update included project components located throughout the City (see Figure 1,
Project Location, below). Project components in the 2008 DMP Update are organized by basin. Appendix
A shows the locations of the 11 project components as presented in the proposed DMP Update.
1.3 PROJECT SPONSOR’S NAME AND ADDRESS
City of Carlsbad
1635 Faraday Avenue
Carlsbad, California 92008
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Exhibit 1: Major Watersheds/Basins A–D
Carlsbad City Limit
Watersheds
A Buena Vista Creek
B Agua Hedionda Creek
C Encinas Creek
D San Marcos Creek NO SCALE
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1.4 BACKGROUND AND PROJECT CONTEXT
1.4.1 2008 DMP Update
The 2008 DMP Update is a comprehensive planning document that serves to assess existing storm drain
infrastructure and drainage areas, identify anticipated improvements and additional infrastructure
required to prevent flooding and accommodate storm flows resulting from future development within the
city, and provide guidance on developing a Planned Local Drainage Area (PLDA) fee program to facilitate
construction of specific drainage facilities. Under such a program, fees paid by developers are used by the
City to construct and maintain storm water infrastructure required for handling the increased storm water
flows resulting from new developments. These projects are referred to as PLDA projects in the 2008 DMP
Update. The 2008 DMP Update also included non-PLDA projects, including Capital Improvement Projects
(CIPs) that involve improvements to existing drainage facilities, as well as operation and maintenance-
related activities for both PLDA and non-PLDA projects. These projects are all considered components of
the 2008 DMP Update, and most were evaluated at a programmatic level in the EIR. In addition to the
program-level analysis of PLDA and non-PLDA project components that were at a preliminary stage of
design, some components identified with the 2008 DMP Update were at a point in the design process that
enabled a project-level analysis. Specifically, the City identified and initiated design of the Agua Hedionda
and Calavera Creeks Dredging and Improvements Project, which was evaluated at a project level in the EIR.
Section 1.4 of the 2008 DMP Update EIR (pages 1-9 to 1-10) includes a discussion of the programmatic
level of analysis, the variation in the stages of design of project components, and the potential for future
project components to be identified:
Each of the components included in the DMP Update is currently in a different stage of
planning and design, with some facilities nearing design completion, while others remain
in preliminary planning stages. Because the DMP Update is a planning document
intended to assess drainage infrastructure needs several decades into the future, there is
not enough specific information available to identify all necessary future components or
to provide detailed analysis of each project. Different degrees of project information are
currently available for each proposed facility, and the EIR analyzes each facility to the
level of detail possible given the stage of project design.
It further states that:
The City will conduct project level environmental review during the design phase for all
proposed DMP Update project components addressed at a program level in this EIR, as
well as any project components identified in the future. This review will determine
whether the project, including construction- and/or operation-related activities, is
consistent with what was described within the scope of the EIR and whether the project
may cause a significant effect on the environment that was not originally examined in
the EIR. This review of program components will determine whether an additional CEQA
analysis and/or document is required. This EIR will be used to streamline the
environmental review process. Where subsequent components and/or activities are
found to be within the scope of the DMP Update as described in this EIR, and no
additional environmental effects could occur beyond those examined in this EIR,
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CIP Project No. 6623
Addendum 1-14 January 2026
additional environmental analysis and documentation would not be required. The
detailed requirements of how to use a program EIR for later activities are specified in
CEQA Guidelines Section 15168(c).
If a subsequent activity is determined to have effects that are not adequately addressed
within the EIR, the project level environmental review described above would be
prepared for the specific activity to allow the City to make an environmental
determination regarding the appropriate supplemental or subsequent CEQA document
to address the proposed DMP Update component. Such documents include an
Addendum, Negative Declaration, Mitigated Negative Declaration, or EIR. Subsequent
CEQA documents would incorporate by reference the general discussions from this
broader EIR, primarily concentrating on the issues specific to the action being evaluated.
Project design features/methods and applicable mitigation measures would also be
incorporated into subsequent project components. If the City, as lead agency under
CEQA, determines that a proposed project would have no additional effect on the
environment that was not identified in the EIR and that no new or additional mitigation
measures or alternatives would be required, the City will make a written finding based
upon the information contained in the original CEQA analysis that the project is within
the scope of the EIR (Section 15091). This process for project level environmental review
would be conducted for program level PLDA, non-PLDA, and operation and maintenance
activities identified in this EIR, as well as for potential future DMP components, identified
as development in the city continues, which are not currently included in the DMP
Update.
1.4.2 Project Changes
Beginning in 2019, the City undertook an update of the DMP, including collection and review of updated
baseline information for storm drain infrastructure, hydrologic soil groups, and land use. This was
followed by a drainage assessment using hydrologic and hydraulic modeling to develop an existing
conditions model. The results from the existing conditions model were used to identify and prioritize
drainage infrastructure CIP projects for the City. Ultimately, 11 PLDA project components were
identified as the most critical to address current storm drain conveyance deficiencies, while considering
effects of future development activity in the City. These project components are described further in
Section 2.0, Project Description, and are collectively referred to as the “New or Revised Project
Components” or “Project Changes” as presented in the City of Carlsbad Drainage Master Plan Update
(proposed DMP Update).
All of the New or Revised Project Components are located within the project area described in the 2008
DMP Update EIR (i.e., within the City of Carlsbad). The New or Revised Project Components include:
x Four new project components,
x Six project components that were included in the 2008 DMP Update EIR but have been refined, and
x One multi-purpose detention basin that was previously included as part of a different project
component.
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CIP Project No. 6623
January 2026 1-15 Addendum
All of the New or Revised Project Components fall within the range of project types identified in Section
3.3.2 of the 2008 DMP Update EIR (pages 3-11 to 3-12), which include reinforced concrete pipe (RCP),
concrete and soft-bottom trapezoidal channels, drainage inlets, manhole cleanouts, junction structures,
perforated subdrains, gabion structures, sediment basins, water quality basins, erosion and scour
protection, slope stabilization, installation of Vmax (slope stabilization matting), and bridge
construction. Furthermore, construction activities associated with the New or Revised Project
Components are consistent with Section 3.3.5 of the 2008 Update DMP EIR (pages 3-24 to 3-27), which
provides an overview of project design features/methods and construction activities associated with
pipeline construction; storm drain infrastructure construction/improvements; existing channel
enhancement; erosion and scour protection; bridge construction/rehabilitation; dredging and sediment
removal; and construction schedule, staging areas, and traffic control. Refer to Appendix B of this
Addendum for relevant excerpts from the 2008 DMP Update EIR.
This Addendum addresses all of the New or Revised Project Components as presented in the proposed
DMP Update, which include four components that fall within the category of potential future DMP
components envisioned in the 2008 DMP Update EIR. As noted in Section 1.4 of the 2008 DMP Update
EIR, “the City will conduct project level environmental review during the design phase for all proposed
DMP Update project components addressed at a program level in this EIR, as well as any project
components identified in the future.” Given the limited design information available for the New or
Revised Project Components, a programmatic level of analysis of impacts remains appropriate. As
supported by the analysis in this document, the impacts of the New or Revised Project Components
would be similar to those identified in the EIR, and no substantial changes to the programmatic analysis
in the 2008 DMP Update EIR are needed. Preparation of an Addendum is therefore appropriate
pursuant to CEQA.
As described in Section 1.4 of the 2008 DMP Update EIR, the City will conduct project-level
environmental review during the design phase for all 2008 DMP Update project components addressed
at a program level, including the 11 that are the subject of this document. Permitting needs would also
be addressed during each component’s design phase. Permit requirements will vary by location and by
potential impacts to habitat/resources. Permits that may be required include a Coastal Development
Permit, a Habitat Management Plan (HMP) Permit, a Hillside Development Permit, and a Special Use
Permit (floodplain).
1.5 OVERVIEW OF CEQA GUIDELINES
Section 15160 of the State CEQA Guidelines explains that there are several mechanisms, and variations
in environmental documents, that can be tailored to different situations and intended uses of
environmental review. Specifically, Section 15160 states that the “…variations listed [including
Subsequent EIRs, Supplemental EIRs, and addendums] are not exclusive. Lead agencies may use other
variations consistent with the Guidelines to meet the needs of other circumstances.” This provision
allows lead agencies to tailor the use of CEQA mechanisms (such as this addendum) to fit the
circumstances presented to the lead agency by a project. Here, the City has opted to prepare an
addendum to assess the minor modifications of the project that have transpired since preparation of the
EIR.
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CIP Project No. 6623
Addendum 1-16 January 2026
Public Resources Code Section 21166 and State CEQA Guidelines Section 15162 and Section 15164 set
forth the criteria for determining the appropriate additional environmental documentation, if any, to be
completed when changes are proposed to a project that has a previously certified EIR. When considering
the need for additional environmental review, the fundamental determination a lead agency must make
is whether the previously certified EIR retains some informational value or whether changes in the
project or circumstances have rendered it wholly irrelevant. If the previously certified EIR has continuing
informational value, the lead agency then must determine whether the proposed changes in the project
require additional environmental review under Public Resources Code Section 21166 and State CEQA
Guidelines Section 15162.
State CEQA Guidelines Section 15164 states that a lead agency shall prepare an addendum to a
previously certified EIR if some changes or additions are necessary, but none of the conditions described
in Section 15162 calling for preparation of a subsequent EIR have occurred. State CEQA Guidelines
Section 15162(a) states that no Subsequent or Supplemental EIR shall be prepared for a project with a
certified EIR unless the lead agency determines, based on substantial evidence in the light of the whole
record, one or more of the following:
1. Substantial changes are proposed in the project which will require major revisions of the previous
EIR or negative declaration due to the involvement of new significant environmental effects or a
substantial increase in the severity of previously identified significant effects;
2. Substantial changes occur with respect to the circumstances under which the project is undertaken
which will require major revisions of the previous EIR or Negative Declaration due to the
involvement of new significant environmental effects or a substantial increase in the severity of
previously identified significant effects; or
3. New information of substantial importance, which was not known and could not have been known
with the exercise of reasonable diligence at the time the previous EIR was certified as complete or
the Negative Declaration was adopted, shows any of the following:
a. The project will have one or more significant effects not discussed in the previous EIR;
b. Significant effects previously examined will be substantially more severe than shown in the
previous EIR;
c. Mitigation measures or alternatives previously found not to be feasible would in fact be feasible,
and would substantially reduce one or more significant effects of the project, but the project
proponents decline to adopt the mitigation measure or alternative; or
d. Mitigation measures or alternatives which are considerably different from those analyzed in the
previous EIR would substantially reduce one or more significant effects on the environment, but
the project proponents decline to adopt the mitigation measure or alternative.
The 2008 DMP Update EIR remains valid and is the certified CEQA document for future actions
associated with implementation of DMP project components. This Addendum has been prepared by the
City because the construction and operation of the New or Modified Project Components is consistent
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CIP Project No. 6623
January 2026 1-17 Addendum
with the overall project evaluated in the 2008 DMP Update EIR and does not require major revisions to
the EIR due to new significant impacts or substantial increases in the severity of previously identified
significant impacts. The anticipated environmental impacts of the Project Changes, as explained in detail
in the following analysis, have been analyzed and mitigated accordingly in the certified 2008 DMP
Update EIR, and there have been no new circumstances since that time that would result in new or
more severe significant environmental impacts. As evaluated in the supporting analysis of this
Addendum, mitigation measures that were previously identified in the 2008 DMP Update EIR, or similar
to previously-identified measures, would continue to ensure that impacts are reduced to less than
significant levels.
Pursuant to State CEQA Guidelines Section 15164(c), an Addendum need not be circulated for public
review, but can be included in or attached to the adopted EIR. Prior to its consideration of the proposed
modifications, the City will review and consider this Addendum together with the 2008 DMP Update EIR
when making a decision regarding the proposed modifications.
1.6 FINDINGS OF THIS ADDENDUM
The City is the lead agency for the proposed project. The City has determined that analyses of a project’s
environmental effects are best provided through the use of an Addendum and that none of the
conditions set forth in Public Resources Code Section 21166 or Section 15162 of the State CEQA
Guidelines requiring preparation of a subsequent or supplemental EIR have been met.
1. There are no substantial changes to the project that would require major revisions of the certified
2008 DMP Update EIR due to new significant environmental effects or a substantial increase in
severity of impacts identified in the 2008 DMP Update EIR;
2. Substantial changes have not occurred in the circumstances under which the project is being
undertaken that will require major revisions to the 2008 DMP Update EIR to disclose new significant
environmental effects or that would result in a substantial increase in severity of impacts identified
in the 2008 DMP Update EIR; and
3. There is no new information of substantial importance that was not known at the time the 2008
DMP Update EIR was certified, indicating any of the following:
x The project will have one or more new significant effects not discussed in the 2008 DMP Update
EIR;
x There are impacts determined to be significant in the 2008 DMP Update EIR that would be
substantially more severe;
x There are additional mitigation measures or alternatives to the project that would substantially
reduce one or more significant effects identified in the 2008 DMP Update EIR; and
x There are additional mitigation measures or alternatives rejected by the project proponent that
are considerably different from those analyzed in the 2008 DMP Update EIR that would
substantially reduce a significant impact identified in that EIR.
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CIP Project No. 6623
Addendum 1-18 January 2026
The complete evaluation of potential environmental effects of the project, including rationale and facts
supporting the City’s findings, is contained in Section 3.0 of this Addendum.
1.7 LOCATION OF PRIOR ENVIRONMENTAL DOCUMENT
The location and custodian of the 2008 DMP Update EIR is the City Clerk, 1200 Carlsbad Village Drive,
Carlsbad, CA 92008.
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CIP Project No. 6623
January 2026 2-1 Addendum
2.0 PROJECT DESCRIPTION
Environmental Setting, Chapter 2.0 of the 2008 DMP Update EIR, presents the environmental setting for
the project. Information regarding the project background can be found in Section 3.1 (pages 3-1 to 3-3)
in the 2008 DMP Update EIR, which provides an overview of previous DMPs, including the 1971
Drainage Master Plan, the 1980 Drainage Master Plan, the 1994 Master Drainage and Storm Water
Quality Management Plan, and the 1996 Update to the Master Drainage and Storm Water Quality
Management Plan. As stated in Section 1.4.2 of this Addendum, all of the New or Revised Project
Components fall within the range of project types identified in Section 3.3.2 of the 2008 DMP Update
EIR (pages 3-11 to 3-12), and construction activities associated with the New or Revised Project
Components are consistent with Section 3.3.5 of the 2008 DMP Update EIR (pages 3-24 to 3-27). The
text of Sections 3.3.2 and 3.3.5 of the 2008 DMP Update EIR are included as Appendix B of this
Addendum for reference.
2.1 PROJECT COMPONENTS
The 11 DMP project components include four that were not previously described in the 2008 DMP
Update EIR. In addition, minor changes are proposed to six project components that were previously
included in the 2008 DMP Update EIR (see Table 3-1, pages 3-13 to 3-19), and the multi-benefit basin
previously included as component “AC” is now a separate project component. The revised components
fall within the description of the types of projects identified in Section 3.3.2 of the 2008 DMP Update
EIR, and the nature of work is consistent with the project design features/methods and construction
activities described in Section 3.3.5 of the 2008 DMP Update EIR. These components have been included
in this Addendum to identify any applicable updates to anticipated impacts.
As noted in Section 1.4.2 of this Addendum and described in Section 1.4 of the 2008 DMP Update EIR,
the City will conduct project-level environmental review during the design phase for all project
components addressed at a program level in the EIR, including the 11 that are the subject of this
document. At the design phase for each project component, site-specific analysis will be undertaken,
consistent with Section 1.4 of the 2008 DMP EIR. Coordination with the City Planning Department will
include completion of the necessary application forms and project-level environmental review.
Table A provides an overview of the four New Project Components, and Table B provides an overview of
the Revised Project Components that were previously included in the 2008 DMP Update EIR. Together,
these 11 components comprise the Project Changes for the proposed DMP Update that are the subject
of this Addendum.
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CIP Project No. 6623
Addendum 2-2 January 2026
Table A: Summary of New Proposed DMP Update PLDA Project Components
Project
Component
ID Name/Location Project Component Description
Basin A – Buena Vista Creek Watershed
BVC-2 Jefferson Street South
Along Jefferson Street south of
the intersection with Laguna
Drive to approximately the
intersection with Home Avenue
This component includes construction of a 24-inch to 36-inch storm
drain backbone along Jefferson Street from south of Laguna Drive to
approximately Home Avenue to mitigate surface conveyance during
the 10-year storm event. The proposed component consists of
approximately 370 linear feet of 24-inch RCP, 540 linear feet of 36-inch
RCP, and 50 linear feet of 18-inch RCP. The project ties into the
existing storm drain backbone along Laguna Drive. Additionally, 4 curb
inlets with lateral connections would be placed at Home Avenue and
Arbuckle Place.
BCV-3 Marron and Monroe Drainage
Improvements
Along Monroe Street between
Carlsbad Village Drive and
Marron Road, near The Shoppes
at Carlsbad
This component consists of two parts. The first is a new 36-inch RCP
along Monroe Street, parallel to the existing system, which will
discharge to the western basin at the intersection of Marron and
Monroe. The second is a diversion structure with two 18-inch RCPs,
which will direct lower flows from the main storm drain system to both
the existing storage basins. The component consists of approximately
680 linear feet of 18-inch RCP, 570 linear feet of 30-inch RCP, 1780
linear feet of 36-inch RCP, and 325 linear feet of 42-inch RCP storm
drainpipe. Approximately 10 Type-A cleanout structures will be
included for maintenance access.
BVC-5 Laguna Drive Storm Drain Upsize
Along Laguna Drive from State
Street on the west to Davis
Avenue on the east
This component would replace the existing RCP storm drain pipe with a
larger diameter pipe to increase conveyance capacity. This will consist
of approximately 1,030 linear feet of 36-inch RCP, 940 linear feet of 48-
inch RCP, and 10 Type-A cleanout structures for maintenance access.
Basin B – Agua Hedionda Creek Watershed
AHC-4 Park Drive and Hillside Drive
Storm Drain Upsize
Southeast along Park Drive from
the Park Drive and Hillside Drive
intersection to the storm drain at
the Park Drive and Adams Street
intersection
This component would upsize 980 linear feet of 48-inch RCP on Park
Drive to 60-inch RCP to mitigate surface conveyance during a 100-year
storm event. The component ties into the existing 60-inch storm drain
at the intersection of Park Drive and Adams Street. Approximately 4
Type-A cleanout structures would be included for maintenance access.
DMP = Drainage Master Plan; ID = Identification; PLDA = Planned Local Drainage Area; RCP = reinforced concrete pipe
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
January 2026 2-3 Addendum
Table B: Summary of Revised 2008 DMP Update PLDA Project Components
Project
Component
ID Name/Location Description in 2008 DMP Update EIR Revised Project Component Description
Basin A – Buena Vista Creek Watershed
BVC-1 Jefferson Street
North
Along Jefferson
Street from south
of the intersection
with Knowles
Avenue to the
corner of
Jefferson Street
and Laguna Drive
The Jefferson Street Drainage Project
would collect on-site runoff from the
residential areas north of Laguna Drive
and included:
x Construction of approximately 550
linear feet of 36-inch RCP along
Jefferson Street
x Four drainage inlets
x One manhole cleanout
The Jefferson Street North component
includes the following improvements:
x Construction of approximately 570
linear feet of 36-inch RCP storm drain
backbone running south along
Jefferson Street, north of the Laguna
Drive and Jefferson Street intersection
x Proposed 5 inlets and approximately
50 linear feet of 18-inch laterals are
placed along Jefferson Street on the
east side of the road
x Realignment of the existing 18-inch
RCP lateral that ties into the storm
drain backbone along Laguna Drive to
tie into the proposed storm drain
backbone on Jefferson Street
x The project ties into the existing storm
drain backbone along Laguna Drive
x This component may result in
disruptions to areas protected by the
HMP, which would require an HMP
Permit or HMP Amendment; specifics
regarding the scale and scope of
habitat impacts will be analyzed upon
submittal of plans for discretionary
approval at a later date
BVC-4 Marron and
Jefferson Multi-
Benefit Basin
Located at the
intersection of
Jefferson Street
and Marron Road
near The Shoppes
at Carlsbad
This component is the natural
desiltation basin mentioned in the
Highland Drive Drainage Project
(project component ID AC), which
would collect on-site runoff from the
residential areas surrounding Highland
Drive and included:
x Construction of approximately
1,000 linear feet of 36-inch RCP
x Six drainage inlets
x Three manhole cleanouts
x Pipe would discharge to a
proposed 600-foot-long
trapezoidal channel and into a
natural desiltation basin southwest
of Jefferson Street and Marron
Road
The Marron and Jefferson Multi-Benefit
Basin includes the following engineering
features:
x Approximately 120 linear feet of 18-
inch RCP crossing Marron Road and
discharging into the basin
x Approximately 200 linear feet of 18-
inch RCP serving as the primary
outflow pipe for the basin
x 2 curb inlets and 4 Type-A cleanout
structures
x An increase in basin storage from a
0.42-acre basin bottom to 1.5-acre
basin bottom
x Retrofit of approximately 1.5 acres of
existing wetlands/detention area
x This component has the potential to
conflict with existing trails within the
Hosp Grove Park; impacts to trails or
land use, if any, will be analyzed when
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CIP Project No. 6623
Addendum 2-4 January 2026
Table B: Summary of Revised 2008 DMP Update PLDA Project Components
Project
Component
ID Name/Location Description in 2008 DMP Update EIR Revised Project Component Description
plans for discretionary approval are
submitted at a later date
Basin B – Agua Hedionda Creek Watershed
BJ-1 Rancho Carlsbad
Multi-Benefit
Basin
South of Cannon
Road/Bobcat
Boulevard at
intersection with
College Boulevard
The Rancho Carlsbad Detention Basin
Project would contain water during a
100-year storm event and included the
following:
x Construction of a retention basin,
designed to contain 49 acre-feet of
water during a 100-year storm
event
x A 270-foot-long reinforced
concrete box culvert (3-foot by 6-
foot)
The Rancho Carlsbad Multi-Benefit Basin
includes the following:
x Construction of a multi-benefit basin
with a footprint of approximately 2.2
acres (located within the southern 3.4
acres of the parcel) and depth of 6
feet, to provide sediment capture,
low-flow reduction, and stream
restoration benefits
x Construction of outlet works of the
basin, consisting of 300 linear feet
long, 6-foot wide by 3-foot deep
reinforced concrete box to convey
flow under the future College
Boulevard Expansion project
x This component may require a General
Plan Amendment to align the
developable areas with the
conveyance and open space, but the
total area of residential-zoned
developable land would not change
AHC-2 College Boulevard
Storm Drain
Extension
Northeast of the
College Boulevard
and El Camino
Real intersection
The College Boulevard Drainage
Project Phase V – Downstream Portion
would connect the existing drainage
facility located on the northwest side of
the intersection of El Camino Real and
College Boulevard and convey runoff to
Agua Hedionda Creek Watershed. This
component included:
x Construction of approximately 600
linear feet of 90-inch RCP
x Four drainage inlets
x One manhole cleanout
x One junction structure
x Outlet head wall, configured to
pass through a new bridge
abutment proposed over College
Boulevard
The current facility is an existing 78-inch
diameter RCP, which discharges to an open
channel tributary to Agua Hedionda Creek
Watershed. The College Boulevard Storm
Drain Extension will need to be configured
to fit through a new bridge abutment
associated with the College Boulevard
Expansion Project. This component consists
of the following:
x Approximately 120 linear feet of 90-
inch RCP
x Modified cleanout structure
x Headwall structure
x D-40 riprap energy dissipater for
concentrated flows
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CIP Project No. 6623
January 2026 2-5 Addendum
Table B: Summary of Revised 2008 DMP Update PLDA Project Components
Project
Component
ID Name/Location Description in 2008 DMP Update EIR Revised Project Component Description
AHC-3 Cantarini and
Holly Springs
Culvert
East of the
Rancho Carlsbad
Golf Course,
approximately
1,800 feet
northeast of the
College Boulevard
and El Camino
Real intersection
The Cantarini and Holly Springs
Development would provide a culvert
and would be constructed using open
trench techniques; trench boxes would
be utilized to shore the sidewalls to
minimize the disturbance of the
existing roadway and to minimize
conflicts with existing utilities. This
component included construction of:
x 155 linear feet of 66-inch diameter
culvert
x Inlet headwall
x Impact dissipater
x Rock slope protection at the outlet
for velocity dissipation
The Cantarini and Holly Springs Culvert
will be placed at a future vehicular bridge
crossing associated with the College
Boulevard Expansion Project, and includes
the following:
x Approximately 155 linear feet of 66-
inch diameter RCP
x Headwall structures at the culvert inlet
and outlet
x D-40 riprap energy dissipaters
Basin C – Encinas Creek Watershed
EC-1 Paseo Del Norte
Box Culvert
Approximately
1,800 feet south
of Palomar
Airport Road,
along Paseo Del
Norte
The Paseo Del Norte Drainage
Improvements would provide
additional capacity to the existing
bridge under the lanes of Paseo Del
Norte to alleviate localized flooding,
and included construction of:
x Approximately 90 linear feet of 10-
foot by 4-foot reinforced concrete
box culvert
The Paseo Del Norte Box Culvert would
provide an additional culvert to increase
conveyance capacity for flow beneath
Paseo Del Norte. The component includes
construction of:
x Approximately 100 linear feet of 10-
foot by 5-foot reinforced concrete box
x Modifications to the inlet and outlet
headwall structures
x D-40 riprap energy dissipater at the
existing triple-reinforced concrete box
Basin D – San Marcos Creek Watershed
SMC-1 Batiquitos Lagoon
Stormwater
Treatment
System
Intersection of
Hummingbird
Road and Rock
Dove Street
The Batiquitos Lagoon Stormwater
Treatment System would provide a
sedimentation basin that would be fed
by an existing 72-inch RCP and would
serve as a water treatment facility by
controlling on-site and channel runoff,
reducing sediment transport within the
flow of the natural tributary, and
reducing the velocity of the flow to
minimize the erosion. The facility
would include the following:
x Concrete treatment device that
will settle out constituents and
discharge runoff directly into
Batiquitos Lagoon
x Entrance and exit weir
x Vegetation where appropriate
The Batiquitos Lagoon Stormwater
Treatment System would provide a storm
water treatment drain designed to provide
equal or greater treatment than existing
water quality basin within a privately-
owned lot (which was intended to be
temporary). The system would include:
x A low-flow bypass from the existing
cleanout at the confluence to a
hydrodynamic separator unit
x A subsurface storage unit
x A compact biofiltration Best
Management Practice (BMP)
DMP = Drainage Master Plan; EIR = Environmental Impact Report; HMP = City of Carlsbad Habitat Management Plan; PLDA = Planned Local
Drainage Area; RCP = reinforced concrete pipe
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CIP Project No. 6623
Addendum 2-6 January 2026
2.1.1 Updates to Local Regulations
Several City regulations and ordinances refer to the 2008 DMP Update as the applicable Drainage
Master Plan. Amendments and/or revisions will be required to change these to reflect the proposed
DMP Update. Title 21 of the Carlsbad Municipal Code (CMC) (City of Carlsbad 2025) would be updated
to reflect the revised DMP through a Zoning Code Amendment. This would be filed concurrently with an
amendment to the Local Coastal Program Land Use Plan, which will require a Local Coastal Program
Amendment (LCPA) application. Applicable forms would need to be completed and submitted with the
necessary filing fees. The joint application requires approval from the Planning Commission, the City
Council, and the California Coastal Commission. Approval of the LCPA is necessary for the proposed DMP
Update to be effective in the Coastal Zone.
Changes to CMC Chapters 15.12 (Stormwater Management and Discharge Control), 15.16 (Grading and
Erosion Control), and 21 (Zoning) require an LCPA. Title 15 and other sections would not require an LCPA
or Planning Commission approval. Changes to other sections of Title 15, or parts of the CMC other than
Title 21, would not require an LCPA or Planning Commission approval but would require City Council
approval..
The City’s Climate Action Plan (CAP) (City of Carlsbad 2024) is a comprehensive plan that outlines
specific activities needed to reduce greenhouse gas (GHG) emissions to meet statewide goals. The CAP
incorporates City sponsored initiatives, actions, and policies including the City’s five-year strategic plan
(City of Carlsbad 2022). This strategic plan incorporates a number or related City plans including the
DMP (both the 2008 Update and the proposed DMP Update). Because the DMP was incorporated into
the City’s strategic plan, and subsequently into the CAP, and the proposed DMP Update does not
substantially affect the potential for project components to emit GHGs or otherwise conflict with CAP
provisions, no updates to the CAP are required.
The City’s Growth Management Program1 was created in the late 1980s in response to community
concerns about the rapid increase in new housing and potential effects on Carlsbad’s quality of life. The
Growth Management Program requires new development to plan for, construct, and pay for the public
infrastructure and facilities necessary to serve the development. The Growth Management Ordinance
(CMC Chapter 21.90) sets forth the purpose and elements of the Growth Management Program. To
ensure that the City has the necessary facilities and infrastructure to meet the needs of new residents,
the Growth Management Program includes several performance standards, set forth in the Citywide
Facilities and Improvement Plan (City of Carlsbad 1986, as amended), that must be met before new
residential development can be approved. The Drainage Performance Standard (which is the standard
most relevant to the proposed DMP update) states that “drainage facilities must be provided as
required by the City concurrent with development.” The proposed DMP Update would continue to
collect PLDA fees (with potential for reassessing the fees as necessary to reflect the identified
improvements), consistent with the existing standard; therefore, no changes to the Drainage
Performance Standard would be required.
1 City of Carlsbad. About Growth Management. Website: https://www.carlsbadca.gov/departments/
community-development/growth-management/about-growth-management (accessed August 15, 2025).
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CIP Project No. 6623
January 2026 3-1 Addendum
3.0 ENVIRONMENTAL ANALYSIS
The environmental analysis supporting the City’s action in approving the Project Changes can be found
in the 2008 DMP Update EIR, the adopted Mitigation Monitoring and Reporting Program (MMRP), and
the analysis contained within the body of this Addendum. As permitted in Section 15150 of the State
CEQA Guidelines, this Addendum incorporates these documents by reference. Documents incorporated
by reference are available for review at the City of Carlsbad offices, located at 1635 Faraday Avenue,
Carlsbad, California 92008.
The analysis of the New and Modified Project Components is programmatic, which is appropriate, given
the level of design available at this time, and is consistent with the approach in the 2008 DMP Update
EIR.
3.1 FINDINGS OF THE 2008 DMP UPDATE EIR
The 2008 DMP Update EIR included a program-level assessment of the potential impacts of the actions
anticipated to be implemented under the 2008 DMP Update, including PLDA Project Components.
With respect to PLDA Project Components, the 2008 DMP Update EIR found that the project would
result in potentially significant but mitigable impacts to Noise, Biological Resources, Cultural Resources,
and Paleontological Resources. Impacts related to other issue areas, including Land Use, Agricultural
Resources, Visual Resources, Transportation/Circulation, Air Quality, Recreation, Geology/Soils, and
Hydrology/Water Quality, would be less than significant.
The 2008 DMP Update EIR found that cumulative biological resources impacts would occur. Although
impacts to biological resources caused by the 2008 DMP Update would contribute to significant
biological impacts in the region and would be significant prior to mitigation, implementation of the
mitigation measures outlined in the 2008 DMP Update EIR would reduce these impacts to a less than
significant level, both directly and in consideration of the cumulative context.
Section 6.4 of the 2008 DMP Update EIR (pages 6-4 to 6-7) indicates that the following issue areas were
not considered to be areas of controversy and were not anticipated to be subject to impacts from
implementation of the 2008 DMP Update: Population and Housing, Energy Resources, Public Services
and Utilities, and Hazards and Hazardous Materials. Section 6.4 of the 2008 DMP Update EIR provides
the rationale for these determinations; no changes are needed to address the inclusion of the New or
Modified Project Components identified in the proposed DMP Update.
3.2 ADDENDUM METHODOLOGY
The City had previously prepared the 2008 DMP Update EIR. No legal actions were filed challenging this
previous CEQA document. It is therefore presumed to be valid. Since adoption of this document, there
have been no substantial changes in the City’s policies that relate to actions in the DMP Update. There
has also not been new information, or a change in circumstances, that would invalidate the previous
CEQA document.
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
Addendum 3-2 January 2026
This Addendum compares anticipated environmental effects of the Project Changes with those disclosed
in the certified 2008 DMP Update EIR to review whether any conditions set forth in Section 15162 of the
State CEQA Guidelines requiring preparation of a subsequent or supplemental EIR are met. This
Addendum analyzes the following 12 environmental issue areas that were included in the 2008 DMP
Update EIR:
x Land Use;
x Agricultural Resources;
x Visual Resources;
x Transportation/Circulation;
x Air Quality;
x Noise;
x Recreation;
x Geology/Soils;
x Hydrology/Water Quality;
x Biological Resources;
x Cultural Resources; and
x Paleontological Resources.
For each environmental issue area, this Addendum provides a comparative analysis of the impacts
presented in the 2008 DMP Update EIR. Where appropriate, references to information presented in the
2008 DMP Update EIR are provided. The analysis includes a determination regarding the occurrence of
new significant impacts or an increase in the severity of previously identified impacts that would result
from the Project Changes. Additionally, an analysis is presented to determine whether there are any
changed circumstances or new information relative to the Project Changes. For each environmental
issue area, the following is provided to conduct this comparative analysis:
1. Previous Analysis;
2. Analysis of the Project Changes;
3. Substantial Changes with Respect to Circumstances or New Information of Substantial Importance;
and
4. Conclusion.
The following environmental analysis supports the City’s determination that approval and
implementation of the Project Changes would not result in new significant environmental impacts or a
substantial increase in the severity of previously disclosed impacts covered under the 2008 DMP Update
EIR and related MMRP. This environmental analysis incorporates all applicable mitigation measures
outlined in the 2008 DMP Update EIR and MMRP.
The following presents the environmental analysis of impacts associated with the Project Changes. In
instances where the impacts resulting from several project components would be similar, their
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CIP Project No. 6623
January 2026 3-3 Addendum
corresponding analyses have been grouped together. In instances where impacts differ by project
component, they are discussed separately.
3.3 LAND USE
3.3.1 Previous Analysis
The analysis of the impacts to land use for the 2008 DMP Update is contained in the 2008 DMP Update
EIR, Section 4.1, pages 4.1-1 to 4.1-40. Cumulative impacts related to land use are discussed in Section
5.2.1.1, pages 5-11 to 5-12 of the 2008 DMP Update EIR. With respect to the programmatic evaluation
of the impacts of the PLDA Project Components, the EIR made the following conclusions:
1) The City’s General Plan authorizes existing drainage infrastructure and planned capacity
improvements to support designated land uses in the city. The 2008 DMP Update was
developed based on an evaluation of the most current land use information available, including
information on existing and planned development, General Plan designations, and other land
use planning documents. No General Plan Amendments were proposed. Potential impacts
would be less than significant and no mitigation is required.
2) Construction, operation, and maintenance of some project components would occur within the
coastal zone. However, the City’s Local Coastal Program requires storm drainage facilities in
developed areas to be improved and enlarged according to the City’s DMP. Impacts in the
Coastal Zone and to existing open space areas from construction activities would be short term
and minimized with implementation of the project design features/methods and construction
measures identified in the EIR. Purpose Statement No. 2 of the City of Carlsbad Habitat
Management Plan (HMP) is to allow the City to construct public facility and infrastructure
projects dictated by the City’s Growth Management Plan (GMP). The HMP land use objectives
also include a provision for the continued implementation of the GMP, particularly for ensuring
adequate public facilities to serve new growth. Potential impacts would be less than significant
and no mitigation is required.
Table 3-6 of the DMP EIR includes Project Design Features/Methods and Construction Practices related
to land use. For reference, this table is included in Appendix C of this Addendum. No mitigation
measures were required to address impacts to land use.
3.3.2 Analysis of the Project Changes
3.3.2.1 Direct and Indirect Impacts
As with the project components previously included in the 2008 DMP Update, the New and Revised
Project Components would occur in a variety of land use types including commercial, residential, and
open space. The development of the New and Revised Project Components included an update to
existing and proposed land uses based on the City’s current General Plan Land Use Map (City of Carlsbad
2024). As with the previously-analyzed project components, some of the new project components
would occur within the Coastal Zone, and some would occur within existing or proposed Hardline
Preserve Area as designated in the HMP. All of the new project components fall within the description of
the types of projects identified in Section 3.3.2 of the 2008 DMP Update EIR, and the nature of work is
consistent with the project design features/methods and construction activities described in Section
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CIP Project No. 6623
Addendum 3-4 January 2026
3.3.5 of the 2008 DMP Update EIR. Furthermore, no changes are proposed to the revised project
components that would result in project components that are inconsistent with the descriptions in
Sections 3.3.2 and 3.3.5 of the 2008 DMP Update EIR (see Appendix B of this Addendum).
The City’s General Plan was updated in 2015 and the Local Coastal Program was updated in 2019. The
City’s General Plan Land Use Map was updated in 2024. Table 4.1-2 (pages 4.1-20 to 4.1-29 of the 2008
DMP Update EIR) presents the General Plan land use designation and location for each PLDA project
component, along with an impact description. The 2019 Local Coastal Program incorporates “the City of
Carlsbad Drainage Master Plan” by reference and specifically requires implementation of the measures
identified in the City’s DMP “and amendments thereto.”
The Project Changes evaluated in this Addendum remain consistent with the goals and requirements
identified in the 2008 DMP Update and would thus be consistent with, and would support
implementation of, the 2019 Local Coastal Program. Table C provides updated land use information for
the New and Revised Project Components based on the updated plans. Changes to the General Plan
land use designations are discussed in more detail in Section 3.3.3 of this Addendum. One component,
BJ-1, may require a General Plan Amendment to align the developable area of the parcel with the
conveyance and open space, but the total area of residential-zoned developable land would not change.
The New and Revised Project Components generally remain compatible with the underlying General
Plan land use designations, and no changes to the impact conclusions in the 2008 DMP Update EIR
presented in Section 3.2.1 of this Addendum are necessary.
To incorporate the proposed DMP Update, Title 21 of the CMC would be updated through a Zoning Code
Amendment to reflect the proposed DMP Update and remove any specific references to the 2008 DMP
Update. This is anticipated to be filed concurrently with an amendment to the Local Coastal Program
Land Use Plan, which is required for updates to certain sections of the CMC, including Title 21. The joint
application requires approval from the Planning Commission, the City Council, and the California Coastal
Commission. Approval of the Local Coastal Program Amendment is necessary for the DMP Update to be
effective in the Coastal Zone. As part of the DMP Update, Public Works will work with City planning staff
to identify all CMC and Local Coastal Program sections that need amendment as part of the processing
of the DMP Update. As noted, component BJ-1 may require a General Plan Amendment; this would be
determined upon submittal of the plans for discretionary approval at a later date.
As described in Section 2.1.3, because the DMP was incorporated into the City’s strategic plan, and
subsequently into the CAP, no updates to the CAP are required. In addition, the proposed DMP Update
would be consistent with the Drainage Performance Standard in the Growth Management Program and
would continue to collect PLDA fees (with potential for reassessing the fees as necessary to reflect the
identified improvements), consistent with the existing standard; therefore, no changes to the Drainage
Performance Standard would be required.
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January 2026 3-5 Addendum
Table C: Summary of Potential Land Use Impacts of the New or Revised Project Components
Project
Component
ID1 Name
Within
Coastal Zone
(CZ)?
General Land
Use
Designation2
Existing Land Use3 and
Master/Specific Plan
In HMP
Preserve4? Impact Description
Basin A – Buena Vista Creek Watershed
BVC-1 Jefferson Street
North
Yes ROW, R-23, R-
15, V-B
Existing Land Use -
Roadway, SFR, MFR
Master/Specific Plan –
Village and Barrio
Master Plan
No
(Adjacent)
The project component would occur within the CZ and may
result in disruptions to areas protected by the HMP, which
would result in the need for an HMP Permit or HMP
Amendment. The specifics regarding the scale and scope of
any habitat impacts will be analyzed upon submittal of plans
for discretionary approval at a later date. The project
component would be consistent with Local Coastal Program
Policy 4-7, which requires storm drainage facilities in
developed areas to be improved and enlarged according to
the City’s DMP. Local Coastal Program Policy 3-2 requires
that storm drain alignments that will be carried through or
empty into Buena Vista Lagoon must comply with the
requirements of Sections 30230, 30231, 30233, and 30235 of
the Coastal Act by maintaining or enhancing the functional
capacity of the lagoon. Impacts in the CZ during construction
activities would be short term and minimized with
implementation of the project design features/methods and
construction measures identified in Table 3-6 of the 2008
DMP Update EIR. Furthermore, Mitigation Measures Bio-2a
and Bio-2b would ensure compliance with applicable Local
Coastal Program policies (refer to Section 3.12 of this
Addendum for more information).
BVC-2* Jefferson Street
South
Yes ROW, R-15,
R/O, V-B
Existing Land Use -
Roadway, SFR, MFR,
Office, Commercial
Master/Specific Plan -
Village and Barrio
Master Plan
No The permanent features of this project component are
adjacent to the CZ; a portion of the surrounding project area
is within the CZ. The project component would be consistent
with Local Coastal Program Policy 4-7, which requires storm
drainage facilities in developed areas to be improved and
enlarged according to the City’s DMP. Local Coastal Program
Policy 3-2 requires that storm drain alignments that will be
carried through or empty into Buena Vista Lagoon must
comply with the requirements of Sections 30230, 30231,
30233, and 30235 of the Coastal Act by maintaining or
enhancing the functional capacity of the lagoon. Impacts in
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CIP Project No. 6623
Addendum 3-6 January 2026
Table C: Summary of Potential Land Use Impacts of the New or Revised Project Components
Project
Component
ID1 Name
Within
Coastal Zone
(CZ)?
General Land
Use
Designation2
Existing Land Use3 and
Master/Specific Plan
In HMP
Preserve4? Impact Description
the CZ during construction activities would be short term and
minimized with implementation of the project design
features/methods and construction measures identified in
Table 3-6 of the 2008 DMP Update EIR. Furthermore,
Mitigation Measures Bio-2a and Bio-2b would ensure
compliance with applicable Local Coastal Program policies
(refer to Section 3.12 of this Addendum for more
information).
BVC-3* Marron and
Monroe
Drainage
Improvements
No ROW, OS, R-8 Existing Land Use -
Roadway, Open Space,
SFR, Commercial
Master/Specific Plan –
N/A
No No direct or indirect impacts to land use are anticipated to
occur as a result of the project component. Impacts from
construction activities would be short term and minimized
with implementation of the project design features/methods
and construction measures identified in Table 3-6 of the 2008
DMP Update EIR.
BVC-4 Marron and
Jefferson Multi-
Benefit Basin
Yes ROW, OS, R Existing Land Use -
Roadway, Open Space,
Bay/Lagoon,
Commercial
Master/Specific Plan –
N/A
Existing
Hardline
Preserve
The project component would occur within the CZ and within
the existing Buena Vista Lagoon Ecological Area Hardline
Preserve. This component has the potential to conflict with
existing trails within the Hosp Grove Park; impacts to trails
and/or land use, if any, will be analyzed upon submittal of
plans for discretionary approval at a later date. The project
component would be consistent with Local Coastal Program
Policy 4-7, which requires storm drainage facilities in
developed areas to be improved and enlarged according to
the City’s DMP. Local Coastal Program Policy 3-2 requires
that storm drain alignments that will be carried through or
empty into Buena Vista Lagoon must comply with the
requirements of Sections 30230, 30231, 30233, and 30235 of
the Coastal Act by maintaining or enhancing the functional
capacity of the lagoon. Impacts in the CZ and to existing open
space and HMP Preserve during construction activities would
be short term and minimized with implementation of the
project design features/methods and construction measures
identified in Table 3-6 of the 2008 DMP Update EIR.
Furthermore, Mitigation Measures Bio-2a and Bio-2b would
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January 2026 3-7 Addendum
Table C: Summary of Potential Land Use Impacts of the New or Revised Project Components
Project
Component
ID1 Name
Within
Coastal Zone
(CZ)?
General Land
Use
Designation2
Existing Land Use3 and
Master/Specific Plan
In HMP
Preserve4? Impact Description
ensure compliance with applicable Local Coastal Program
policies (refer to Section 3.12 of this Addendum for more
information).
BVC-5* Laguna Drive
Storm Drain
Upsize
Yes ROW, R-15, R-
23, V-B, O
Existing Land Use -
Roadway, SFR, MFR,
Office, Hotel, Health
Care, Assisted Living,
Park Commercial
Master/Specific Plan -
Village and Barrio
Master Plan
Existing
Hardline
Preserve
The project component would occur within the CZ and
adjacent to the existing Buena Vista Lagoon Ecological Area
Hardline Preserve. The project component would be
consistent with Local Coastal Program Policy 4-7, which
requires storm drainage facilities in developed areas to be
improved and enlarged according to the City’s DMP. Local
Coastal Program Policy 3-2 requires that storm drain
alignments that will be carried through or empty into Buena
Vista Lagoon must comply with the requirements of Sections
30230, 30231, 30233, and 30235 of the Coastal Act by
maintaining or enhancing the functional capacity of the
lagoon. Impacts in the CZ and to existing open space and
HMP Preserve during construction activities would be short
term and minimized with implementation of the project
design features/methods and construction measures
identified in Table 3-6 of the 2008 DMP Update EIR.
Furthermore, Mitigation Measures Bio-2a and Bio-2b would
ensure compliance with applicable Local Coastal Program
policies (refer to Section 3.12 of this Addendum for more
information).
Basin B – Agua Hedionda Creek Watershed
BJ-1 Rancho
Carlsbad Multi-
Benefit Basin
No ROW, R-8, R-4,
R-30, OS
Existing Land Use -
Roadway, Vacant or
Undeveloped,
Landscape Open Space
Master/Specific Plan –
N/A
Standards
Area
The project component is within the Rancho Carlsbad
Standards Area (Future Preserve). Impacts to the HMP
standards area during construction activities would be short
term and minimized with implementation of the project
design features/methods and construction measures
identified in Table 3-6 of the 2008 DMP Update EIR. The
project component would be constructed within Parcel
2090604800, which is 11.6 acres and designated for open
space and high density residential development (minimum of
26.5 dwelling units per acre). The City’s adopted Housing
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CIP Project No. 6623
Addendum 3-8 January 2026
Table C: Summary of Potential Land Use Impacts of the New or Revised Project Components
Project
Component
ID1 Name
Within
Coastal Zone
(CZ)?
General Land
Use
Designation2
Existing Land Use3 and
Master/Specific Plan
In HMP
Preserve4? Impact Description
Element identifies the site as providing 155 units of lower
income housing. The project component would have a
footprint of approximately 2.2 acres (within the southern 3.4
acres of the parcel); therefore, following construction of the
project component, there would be sufficient acreage
remaining on site to accommodate the proposed number of
units. A General Plan Amendment may be required to align
the developable areas with the conveyance and open space,
but the total area of residential-zoned developable land
would not change. The project component would not result
in a net decrease in land designated for residential
development.
AHC-2 College
Boulevard
Storm Drain
Extension
No ROW, R-4, R-8,
OS
Existing Land Use -
Intensive Agriculture,
Vacant or Undeveloped,
Open Space
Master/Specific Plan –
Sunny Creek Specific
Plan
Proposed
Hardline
Preserve
The project component is within the West Senior Living
Proposed Hardline Preserve. Impacts to the HMP Proposed
Preserve during construction activities would be short term
and minimized with implementation of the project design
features/methods and construction measures identified in
Table 3-6 of the 2008 DMP Update EIR.
AHC-3 Cantarini and
Holly Springs
Culvert
No ROW, R-4, R-8,
OS
Exiting Land Use -
Intensive Agriculture,
Vacant or Undeveloped,
Open Space
Master/Specific Plan –
Sunny Creek Specific
Plan
Proposed
Hardline
Preserve
The project component is within the West Senior Living
Proposed Hardline Preserve. Impacts to the HMP Proposed
Preserve during construction activities would be short term
and minimized with implementation of the project design
features/methods and construction measures identified in
Table 3-6 of the 2008 DMP Update EIR.
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January 2026 3-9 Addendum
Table C: Summary of Potential Land Use Impacts of the New or Revised Project Components
Project
Component
ID1 Name
Within
Coastal Zone
(CZ)?
General Land
Use
Designation2
Existing Land Use3 and
Master/Specific Plan
In HMP
Preserve4? Impact Description
AHC-4* Park Drive and
Hillside Storm
Drain Upsize
Yes ROW, R-4 Existing Land Use -
Roadway, SFR
Master/Specific Plan –
N/A
No The project component would occur within the CZ. The
project component would be consistent with Local Coastal
Program Policy 4-7, which requires storm drainage facilities in
developed areas to be improved and enlarged according to
the City’s DMP. Impacts in the CZ during construction
activities would be short term and minimized with
implementation of the project design features/methods and
construction measures identified in Table 3-6 of the 2008
DMP Update EIR. Furthermore, Mitigation Measures Bio-2a
and Bio-2b would ensure compliance with applicable Local
Coastal Program policies (refer to Section 3.12 of this
Addendum for more information).
Basin C – Encinas Creek Watershed
EC-1 Paseo Del
Norte Box
Culvert
Yes ROW, OS, GC,
O
Existing Land Use -
Roadway, Open Space,
Light Industry,
Institutions
Master/Specific Plan –
N/A
Existing
Hardline
Preserve
The project component would occur within the CZ and is
within the Costco Wholesale Hardline Preserve. The project
component would be consistent with Local Coastal Program
Policy 4-7, which requires storm drainage facilities in
developed areas to be improved and enlarged according to
the City’s DMP. Impacts in the CZ and to the HMP Preserve
during construction activities would be short term and
minimized with implementation of the project design
features/methods and construction measures identified in
Table 3-6 of the 2008 DMP Update EIR. Furthermore,
Mitigation Measures Bio-2a and Bio-2b would ensure
compliance with applicable Local Coastal Program policies
(refer to Section 3.12 of this Addendum for more
information).
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CIP Project No. 6623
Addendum 3-10 January 2026
Table C: Summary of Potential Land Use Impacts of the New or Revised Project Components
Project
Component
ID1 Name
Within
Coastal Zone
(CZ)?
General Land
Use
Designation2
Existing Land Use3 and
Master/Specific Plan
In HMP
Preserve4? Impact Description
Basin D – San Marcos Creek Watershed
SMC-1 Batiquitos
Lagoon
Stormwater
Treatment
System
Yes ROW, R-4, R-8,
OS
Existing Land Use -
Roadway, Intensive
Agriculture (Equestrian),
Residential
Master/Specific Plan –
Aviara Master Plan
Existing
Hardline
Preserve
The project component would occur within the CZ and
portions of the project area are within the Murphy Property
Hardline Preserve. The project component would be
consistent with Local Coastal Program Policy 4-7, which
requires storm drainage facilities in developed areas to be
improved and enlarged according to the City’s DMP. Impacts
in the CZ and to the HMP Preserve during construction
activities would be short term and minimized with
implementation of the project design features/methods and
construction measures identified in Table 3-6 of the 2008
DMP Update EIR. Furthermore, Mitigation Measures Bio-2a
and Bio-2b would ensure compliance with applicable Local
Coastal Program policies (refer to Section 3.12 of this
Addendum for more information).
Sources: 2021 Housing Element Update Addendum (City of Carlsbad 2021); Local Coastal Program Land Use Plan (City of Carlsbad 2019); Village and Barrio Master Plan (City of Carlsbad 2019);
Aviara Master Plan (City of Carlsbad 1997).
Note: This table is an update to Table 4.1-2 in the 2008 DMP Update EIR.
1 Project Components marked with * are New Project Components.
2 City of Carlsbad (2024) land use designations have been generalized. Adjacent land uses to each component are included to be conservative. ROW acquisition may not be needed for some
components (or portions of components) as design advances.
3 Existing land use identified using SANDAG land use data (2019) and/or aerial imagery.
4 Includes existing or proposed Hardline Preserve.
Land Use Categories: C= Commercial; GC = General Commercial; I = Industrial; MFR = Multi-Family Residential; OS = Open Space; O = Office; R-4 = Residential (0-4 du/acre); R-8 = Residential (4-8
du/acre): R-15 = Residential (11.5-15 du/acre); R-23 = Residential (19-23 du/ac); R-30 = Residential (26.5-30 du/acre); R = Regional Commercial; Rec = Recreation; R/O = Residential/Office; ROW =
Road/Railroad Rights of Way; SFR = Single Family Residential; S = School; V-B = Village-Barrio; VC = Visitor Commercial
CZ = Coastal Zone; DMP = Drainage Master Plan; EIR = Environmental Impact Report; HMP = Habitat Management Plan; N/A = not applicable; SANDAG = San Diego Association of Governments
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January 2026 3-11 Addendum
Based on the information presented in Table C, no changes to the impact conclusions described in
Section 3.3.1 of this Addendum are needed; impacts would be less than significant and no mitigation is
required.
3.3.2.2 Cumulative Impacts
As with the 2008 DMP Update as evaluated in the 2008 DMP Update EIR, implementation of the
Proposed Changes would not alter planned land use conditions in the City beyond what is envisioned in
the General Plan.2 For these reasons, the Proposed Changes would not contribute to cumulative land
use impacts in the City.
3.3.3 Substantial Changes with Respect to Circumstances or New Information of Substantial
Importance
3.3.3.1 Updates to the General Plan, Local Coastal Program, and Climate Action Plan
As noted in Section 3.3.2, the City’s General Plan and Local Coastal Program have been updated
following the certification of the 2008 DMP Update EIR. The land use designations for New Project
Components are set forth in Table C. Changes to the designated General Plan land use occurred for the
following Revised Project Components:
x BVC-1 and BVC-4 were previously listed as within right-of-way (ROW). For BVC-1, residential has
been added. For BVC-4, open space and commercial have been added.
x AHC-2 were previously listed as residential. ROW and open space are now included.
x SMC-1 was previously listed only as open space. ROW and residential are now included.
x BJ-1 was previously listed as residential/open space. High density residential development and open
space are now included.
As indicated in Table C, New and Revised Project Components are compatible with underlying land use
designations.
As described in Section 2.1.3, the DMP was incorporated into the City’s strategic plan, and subsequently
into the CAP, and no updates to the CAP are required. In addition, the proposed DMP Update would be
consistent with the Drainage Performance Standard in the Growth Management Program and would
continue to collect PLDA fees consistent with the existing standard; therefore, no changes to the
Drainage Performance Standard would be required.
3.3.3.2 State Housing Law
Under Senate Bill 166, cities and counties are required to ensure their housing element inventory can
accommodate its share of the regional housing need throughout the planning period. The law prohibits
2 Although component BJ-1 may require a General Plan Amendment, this would be a minor revision that would
align developable areas, open space, and the proposed basin within the existing parcel; no changes to the
total area of residential-zoned developable areas would occur.
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CIP Project No. 6623
Addendum 3-12 January 2026
a city or county from reducing, requiring, or permitting the reduction of residential density to a lower
level than was utilized by the Department of Housing and Community Development in determining
compliance with housing element law (unless written findings supporting the reduction are consistent
with the adopted general plan and that the remaining sites identified in the housing element are
adequate to accommodate the jurisdiction’s share of the regional housing need).
The Housing Crisis Act of 2019 (HCA) (Senate Bill 330) passed a number of laws to increase residential
unit development, protect existing housing inventory, expedite permit processing, and provide certainty
to developers in the permitting process. Key relevant provisions to this project include Government
Code Section 65941.1 and Senate Bill 330’s amendments to the Housing Accountability Act (HAA)
(California Government Code Section 65589.5(o)), which establish a preliminary application process for
housing developments that allows developers to lock in or “freeze” those ordinances, policies, and
standards that are in effect when a preliminary application is submitted for a project.
California Government Code Section 65943 and amendments to the HAA (e.g., California Government
Code Section 65589.5(j)(2)) establish completeness review requirements for housing development
projects.
California Government Code Section 66300 prevents jurisdictions from enforcing moratoriums, growth
control measures, and other limitations on new housing development. In 2021, the City found that this
provision of State law preempts it from implementing residential growth management plan caps,
residential quadrant limits, and residential control points that were contained in its General Plan,
Growth Management Plan, Policy Statement No. 43, and Municipal Code Chapter 21.90 (City Resolution
No. 2021-074).
California Government Code Section 65905.5 provides that housing projects shall be subject to no more
than five hearings and affirms that “receipt of a density bonus including any incentives, concessions, or
waivers pursuant to Section 65915 shall not constitute a valid basis on which to find that a proposed
housing development project is inconsistent, not in compliance, or not in conformity, with an applicable
plan, program, policy, ordinance, standard, requirement, or other similar provision” (California
Government Code Section 65905.5(a), (c)(1)).
The project component BJ-1 is a multi-benefit basin that would be constructed within an 11.6-acre
parcel (2090604800), which is now designated for open space and high density residential development
(with a minimum of 26.5 dwelling units per acre). The City’s adopted Housing Element identifies the site
as providing 155 units of lower income housing, requiring a minimum of 5.8 acres. If the project
component precluded development of the target number of housing units, a violation of Senate Bill 166
and/or Senate Bill 330 would occur. The parcel is also within an HMP Standards Area, meaning that a
portion of the parcel will become part of the Preserve. The project component would have a footprint of
approximately 2.2 acres (located within the southern 3.4 acres of the parcel); therefore, it is expected
there would be sufficient acreage remaining on site to accommodate the required number of units and
comply with the HMP Standards. A General Plan Amendment may be required to align the developable
areas, open space, and the multi-purpose basin, however, the total area of residential-zoned
developable land would not change. The project component would not result in a net decrease in the
number of units anticipated.
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CIP Project No. 6623
January 2026 3-13 Addendum
3.3.3.3 Determination
Based on a review of land use designations and the policies that formed the basis for land use impact
conclusions in the 2008 DMP Update EIR, the updates to the General Plan and Local Coastal Program
and changes to State Housing Law do not represent a substantial change with respect to circumstances
or new information of substantial importance as the New and Revised Project Components are designed
to support the land uses identified in the updated General Plan. No other substantial changes with
respect to the circumstances under which the project is being undertaken and no new information of
substantial importance have been identified with regard to land use.
3.3.4 Conclusion
Based on the foregoing analysis and information, there is no evidence that the New or Revised Project
Components require a major change to the 2008 DMP Update EIR. The Project Changes would not result
in new significant environmental impacts related to land use and there would not be a substantial
increase in the severity of impacts described in the 2008 DMP Update EIR. Implementation of the
project design features/methods and construction measures identified in Table 3-6 of the 2008 DMP
Update EIR (included in Appendix C of this Addendum) would ensure that temporary and permanent
impacts would remain less than significant and no mitigation is required.
No major changes to the project area or the general scope and magnitude of the project components
have taken place since preparation of the 2008 DMP Update EIR that would require revisions to the
analysis in the EIR. There is no information in the record or otherwise available that indicates that there
are substantial changes in circumstances pertaining to land use that would require major changes to the
2008 DMP Update EIR.
This Addendum has analyzed all available relevant information to determine whether there is new
information that was not available at the time the 2008 DMP Update EIR was certified, indicating that a
new significant effect not reported in that document may occur. Based on the information and analyses
above, there is no substantial new information indicating that there would be a new significant impact
related to land use requiring major revisions to the 2008 DMP Update EIR.
The 2008 DMP Update EIR did not identify any potentially significant land use impacts, and no new
information, mitigation, or alternatives to the project have been identified that would substantially
reduce one or more significant impacts pertaining to land use.
With regards to potential land use impacts, the New and Revised Project Components are within the
scope of the 2008 DMP Update EIR. None of the conditions under Section 15162 requiring a subsequent
EIR have been met.
3.4 AGRICULTURAL RESOURCES
3.4.1 Previous Analysis
The analysis of the impacts to agricultural resources for the 2008 DMP Update is contained in the 2008
DMP Update EIR, Section 4.2, pages 4.2-1 to 4.2-17. Cumulative impacts related to agricultural resources
are discussed in Section 5.2.1.2 on page 5-12 of the 2008 DMP Update EIR. With respect to the
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
Addendum 3-14 January 2026
programmatic evaluation of the impacts of the PLDA Project Components, the EIR made the following
conclusions:
1) Although a number of proposed 2008 DMP Update components would be located within
designated Important Farmland, none of these projects would involve the loss of Important
Farmland or the conversion of existing agricultural land to non-agricultural uses because
proposed 2008 DMP Update components would occur within existing drainage channels or
involve rehabilitation/replacement of existing drainage facilities and would not affect
agricultural land resources or activities, or conflict with existing General Plan policies related to
agricultural land use. 2008 DMP Update components are not proposed within Williamson Act
contract lands or areas zoned for agricultural use. Operation and maintenance activities would
be conducted primarily within existing drainage facilities and would not involve the construction
of new structures on agricultural land. Potential impacts would be less than significant and no
mitigation is required.
2) Although the project is located adjacent to lands designated as Prime Farmland, Farmland of
Statewide Importance, and Unique Farmland, none of the land within the project component
boundaries is designated as Important Farmland. These areas are not suitable for agricultural
uses. None of the land within the project limits is zoned for agricultural use or mapped by the
County of San Diego as being protected under a Williamson Act. Potential impacts would be less
than significant and no mitigation is required.
3.4.2 Analysis of the Project Changes
Table 4.2-2 (pages 4.2-9 to 4.2-13 of the 2008 DMP Update EIR) summarizes the program-level analysis
for impacts to agricultural resources for each PLDA project component. Table D provides information for
the New and Revised Project Components based on a review of the updated General Plan, the City’s
Zoning Ordinance, the Farmland Mapping and Monitoring Program (FMMP) (DOC 2018), and Williamson
Act contracts.
3.4.2.1 Direct and Indirect Impacts
As with the project components previously included in the 2008 DMP Update, some of the New and
Revised Project Components would occur in agricultural areas and/or areas identified in the FMMP. All
of the new project components fall within the description of the types of projects identified in Section
3.3.2 of the 2008 DMP Update EIR, and the nature of work is consistent with the project design
features/methods and construction activities described in Section 3.3.5 of the 2008 DMP Update EIR.
Furthermore, no changes are proposed to the revised project components that would result in project
components that are inconsistent with the descriptions in Sections 3.3.2 and 3.3.5 of the 2008 DMP
Update EIR. No changes to the impact conclusions in the 2008 DMP Update EIR presented in Section
3.2.1 of this Addendum are necessary.
Based on the information presented in Table D, no changes to the impact conclusions described in
Section 3.4.1 of this Addendum are needed; impacts would be less than significant and no mitigation is
required.
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CIP Project No. 6623
January 2026 3-15 Addendum
Table D: Potential Impacts to Agricultural Resources from New or Revised Project Components
Project
Component
ID1 Name
Designated
Farmland
Category
Williamson
Contract
Participant?
Zoned for
Agricultural
Use? Conclusion
Basin A – Buena Vista Creek Watershed
BVC-1 Jefferson Street
North
None No No No impact to agricultural resources would result from the proposed
project component, because no agricultural resources are located in or
near the project component.
BVC-2* Jefferson Street
South
None No No No impact to agricultural resources would result from the proposed
project component, because no agricultural resources are located in or
near the project component.
BVC-3* Marron and Monroe
Drainage
Improvements
None No No No impact to agricultural resources would result from the proposed
project component, because no agricultural resources are located in or
near the project component.
BVC-4 Marron and Jefferson
Multi-Benefit Basin
None No No No impact to agricultural resources would result from the proposed
project component, because no agricultural resources are located in or
near the project component.
BVC-5* Laguna Drive Storm
Drain Upsize
None No No No impact to agricultural resources would result from the proposed
project component, because no agricultural resources are located in or
near the project component.
Basin B – Agua Hedionda Creek Watershed
BJ-1 Rancho Carlsbad
Multi-Benefit Basin
Farmland of
Local
Importance
No No The proposed project component would be constructed within an
existing drainage channel adjacent to an existing road right-of-way. No
Important Farmland would be converted to non-agricultural uses.
Therefore, no impact to agricultural resources would result from the
proposed project component.
AHC-2 College Boulevard
Storm Drain
Extension
None No No Agriculture is an existing land use within the project area. The project
component is the extension of a storm drain and would not convert
farmland to non-agricultural uses. No impact to agricultural resources
would result from the proposed project component.
AHC-3 Cantarini and Holly
Springs Culvert
None No No Agriculture is an existing land use within the project area. The project
component is the installation of a culvert and would not convert
farmland to non-agricultural uses. No impact to agricultural resources
would result from the proposed project component.
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CIP Project No. 6623
Addendum 3-16 January 2026
Table D: Potential Impacts to Agricultural Resources from New or Revised Project Components
Project
Component
ID1 Name
Designated
Farmland
Category
Williamson
Contract
Participant?
Zoned for
Agricultural
Use? Conclusion
AHC-4* Park Drive and
Hillside Storm Drain
Upsize
None No No No impact to agricultural resources would result from the proposed
project component, because no agricultural resources are located in or
near the project component.
Basin C – Encinas Creek Watershed
EC-2 Paseo Del Norte Box
Culvert
None No No No impact to agricultural resources would result from the proposed
project component, because no agricultural resources are located in or
near the project component.
Basin D – San Marcos Creek Watershed
SMC-1 Batiquitos Lagoon
Stormwater
Treatment System
None No No Agriculture is an existing land use within the project area. The project
component is the installation of a storm water treatment system and
would not convert farmland to non-agricultural uses. No impact to
agricultural resources would result from the proposed project
component.
Sources: California Department of Conservation (2018); City of Carlsbad (2021).
Note: This table is an update to Table 4.2-2 in the 2008 DMP Update EIR.
1 Project Components marked with * are New Project Components.
DMP = Drainage Master Plan; EIR = Environmental Impact Report
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CIP Project No. 6623
January 2026 3-17 Addendum
3.4.2.2 Cumulative Impacts
As with the 2008 DMP Update as evaluated in the 2008 DMP Update EIR, implementation of the
Proposed Changes would not involve the conversion of Important Farmlands or existing agricultural uses
to non-agricultural uses and would not conflict with any Williamson Act contracts in the City. For these
reasons, the Proposed Changes would not contribute to cumulative agricultural resources impacts.
3.4.3 Substantial Changes with Respect to Circumstances or New Information of Substantial
Importance
As described in Section 3.4.2, updated information is available related to zoning, land use designations,
and mapped farmland. However, these updates do not result in conflicts with the New and Revised
Project Components, and do not represent a substantial change or provide new information of
substantial importance. No other substantial changes have occurred with respect to the circumstances
under which the project is being undertaken and no new information of substantial importance has
been identified with regard to agriculture.
3.4.4 Conclusion
Based on the foregoing analysis and information, there is no evidence that the New or Revised Project
Components require a major change to the 2008 DMP Update EIR. The Project Changes would not result
in new significant environmental impacts related to agricultural resources, and there would not be a
substantial increase in the severity of impacts described in the 2008 DMP Update EIR. Implementation
of the project design features/methods and construction measures identified in Table 3-6 of the 2008
DMP Update EIR (included in Appendix C of this Addendum) would ensure that temporary and
permanent impacts would remain less than significant and no mitigation is required.
No major changes to the project area or the general scope and magnitude of the project components
have taken place since preparation of the 2008 DMP Update EIR that would require revisions to the
analysis in the EIR. There is no information in the record or otherwise available that indicates that there
are substantial changes in circumstances pertaining to agricultural resources that would require major
changes to the 2008 DMP Update EIR.
This Addendum has analyzed all available relevant information to determine whether there is new
information that was not available at the time the 2008 DMP Update EIR was certified, indicating that a
new significant effect not reported in that document may occur. Based on the information and analyses
above, there is no substantial new information indicating that there would be a new significant impact
related to agricultural resources requiring major revisions to the 2008 DMP Update EIR.
The 2008 DMP Update EIR did not identify any potentially significant impacts to agricultural resources,
and no new information, mitigation, or alternatives to the project have been identified that would
substantially reduce one or more significant impacts pertaining to agricultural resources.
With regards to potential agricultural resource impacts, the New and Revised Project Components are
within the scope of the 2008 DMP Update EIR. None of the conditions under Section 15162 requiring a
subsequent EIR have been met.
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CIP Project No. 6623
Addendum 3-18 January 2026
3.5 VISUAL RESOURCES
3.5.1 Previous Analysis
The analysis of the impacts to visual resources for the 2008 DMP Update is contained in the 2008 DMP
Update EIR, Section 4.3, pages 4.3-1 to 4.3-11. Cumulative impacts related to land use are discussed in
Section 5.2.1.3 on page 5-12 of the 2008 DMP Update EIR. With respect to the programmatic evaluation
of the impacts of the PLDA Project Components, the EIR made the following conclusions:
1) Proposed 2008 DMP Update components would involve construction of new facilities or
replacement and improvements to existing facilities within existing drainages. Many of the
proposed projects would be located at or below grade within or adjacent to the existing road
right-of-way or in developed/disturbed areas, such that views from designated scenic corridors
or scenic vistas are not anticipated to be obstructed or degraded. Design features identified in
the EIR require all design plans to be consistent with scenic corridor design standards, where
applicable. Potential staging areas and access roads may be temporarily visible during
construction activities for some project components. Potential impacts would be less than
significant and no mitigation is required.
2) Construction of proposed 2008 DMP Update components would primarily occur during daylight
hours; however, components proposed within rights-of-way may involve construction during
nighttime hours to minimize traffic-related impacts. Nighttime construction lighting of facilities
would be shielded or directed away from adjacent residences, in accordance with the
construction measures identified in the EIR. The proposed components would not require
permanent lighting features or utilize reflective materials that could create glare. Potential
impacts would be less than significant.
3.5.2 Analysis of the Project Changes
3.5.2.1 Direct and Indirect Impacts
The New and Revised Project Components are primarily located within or in proximity to existing
drainage infrastructure, roadway rights-of-way, or other development. All of the new project
components fall within the description of the types of projects identified in Section 3.3.2 of the 2008
DMP Update EIR, and the nature of work is consistent with the project design features/methods and
construction activities described in Section 3.3.5 of the 2008 DMP Update EIR. Furthermore, no changes
are proposed to the revised project components that would result in project components that are
inconsistent with the descriptions in Sections 3.3.2 and 3.3.5 of the 2008 DMP Update EIR. No new
sources of light or glare would be created as a result of the New or Revised Project Components.
The Project Changes have been reviewed to determine whether any new or substantially different
impacts would occur as a result of the location or nature of New Project Components or modifications
to Revised Project Components. Construction methods and the associated impacts would be consistent
with those previously evaluated in the 2008 DMP Update EIR. Table E provides a summary of the
updated overview of the permanent visual changes associated with each of the New or Revised Project
Components.
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CIP Project No. 6623
January 2026 3-19 Addendum
Table E: Summary of the Visual Changes of the New or Revised Project Components
Project
Component
ID1 Name Project Features Visual Changes
Basin A – Buena Vista Creek Watershed
BVC-1 Jefferson Street
North
Storm drain with inlets
within existing roadway
Permanent visual changes would be minimal, limited to
surface-level changes in the location of inlets and
access points.
BVC-2* Jefferson Street
South
Storm drain with inlets
within existing roadway
Permanent visual changes would be minimal, limited to
surface-level changes in the location of inlets and
access points.
BVC-3* Marron and
Monroe Drainage
Improvements
Storm drain and diversion
structure within existing
roadways and storm water
storage basins
Permanent visual changes would be minimal, limited to
surface-level changes in the location of inlets and
access points.
BVC-4 Marron and
Jefferson Multi-
Benefit Basin
Storm drain with inlets and
cleanout structures within
existing roadway;
expansion of an existing
storm water detention
basin
Permanent visual changes would be associated with the
increase in the size of the existing basin. The basin is
within an existing vegetated area (Hosp Grove). It is
anticipated that vegetation would reestablish within
the basin following implementation of the project
component, resulting in a similar visual character to
existing conditions.
BVC-5* Laguna Drive
Storm Drain
Upsize
Storm drain with cleanout
structures below existing
roadway
Permanent visual changes would be minimal, limited to
surface-level changes in the location of access points.
Basin B – Agua Hedionda Creek Watershed
BJ-1 Rancho Carlsbad
Multi-Benefit
Basin
New multi-benefit basin
with culvert
Permanent visual changes would primarily be
associated with lowering the grade in the area of the
multi-benefit basin. The area is currently partially
vegetated and being used for storage and as private
gardens by the Rancho Carlsbad Homeowners
Association. It is anticipated that vegetation would
establish within the basin following implementation of
the project component. This would have a similar visual
character to existing and surrounding conditions. The
culvert would be located in proximity to existing
drainage infrastructure and would have low visibility
from the surrounding area.
AHC-2 College
Boulevard Storm
Drain Extension
Extension of subsurface
storm drain within
vegetated areas with a
wing type headwall
structure, modified
cleanout structure, and
riprap energy dissipater
Permanent visual changes would primarily be
associated with the aboveground storm drain
infrastructure. This component is located within and
adjacent to vegetation associated with Agua Hedionda
Creek Watershed in an area with relatively low visibility
from the surrounding area. The addition of storm drain
infrastructure would not appreciably change the visual
character of the area.
AHC-3 Cantarini and
Holly Springs
Culvert
New culvert crossing below
future roadway alignment
within vegetated areas with
wing type headwalls and
Permanent visual changes would primarily be
associated with the aboveground storm drain
infrastructure. This component is located within and
adjacent to vegetation associated with Agua Hedionda
Creek Watershed in an area with relatively low visibility
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CIP Project No. 6623
Addendum 3-20 January 2026
Table E: Summary of the Visual Changes of the New or Revised Project Components
Project
Component
ID1 Name Project Features Visual Changes
riprap energy dissipaters at
either end
from the surrounding area. The addition of storm drain
infrastructure would not appreciably change the visual
character of the area.
AHC-4* Park Drive and
Hillside Storm
Drain Upsize
Upsized storm drain and
cleanout structures within
existing roadway
Permanent visual changes would be minimal, limited to
surface-level changes in the location of access points.
Basin C – Encinas Creek Watershed
EC-1 Paseo Del Norte
Box Culvert
Box culvert below existing
roadway with headwalls
and riprap energy
dissipater
Permanent visual changes would be minimal as there
are currently three existing box culverts at this location.
The fourth box culvert would be consistent with the
existing visual character and would have limited
visibility from the surrounding areas.
Basin D – San Marcos Creek Watershed
SMC-1 Batiquitos Lagoon
Stormwater
Treatment
System
Storm water treatment
system within existing
roadway including a
hydrodynamic separator
unit, a subsurface storage
unit, and a compact
Biofiltration BMP
Permanent visual changes would be minimal, limited to
potential surface-level access points.
1 Project Components marked with * are New Project Components.
BMP = Best Management Practice
Based on the information presented in Table E, no changes to the impact conclusions described in
Section 3.5.1 of this Addendum are needed; impacts would be less than significant and no mitigation is
required.
3.5.2.2 Cumulative Impacts
As with the 2008 DMP Update as evaluated in the 2008 DMP Update EIR, implementation of the
Proposed Changes would not result in a substantial change to the visual environment, either
individually, or in consideration of the cumulative effects of ongoing development within the City. For
this reason, the 2008 DMP Update would not contribute considerably to a cumulative visual impact.
3.5.3 Substantial Changes with Respect to Circumstances or New Information of Substantial
Importance
No changes have been identified with respect to the circumstances under which the Project Changes
would be undertaken and there is no new information of substantial importance that has become
available relative to visual resources. No new sensitive receptors or significant scenic resources have
been identified in the vicinity of the New or Revised Project Components.
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CIP Project No. 6623
January 2026 3-21 Addendum
3.5.4 Conclusion
Based on the foregoing analysis and information, there is no evidence that the New or Revised Project
Components require a major change to the 2008 DMP Update EIR. The Project Changes would not result
in new significant environmental impacts related to visual resources, and there would not be a
substantial increase in the severity of impacts described in the 2008 DMP Update EIR. Implementation
of the project design features/methods and construction measures identified in Table 3-6 of the 2008
DMP Update EIR (included in Appendix C of this Addendum) would ensure that temporary and
permanent impacts would remain less than significant and no mitigation is required.
No major changes to the project area or the general scope and magnitude of the project components
have taken place since preparation of the 2008 DMP Update EIR that would require revisions to the
analysis in the EIR. There is no information in the record or otherwise available that indicates that there
are substantial changes in circumstances pertaining to visual resources that would require major
changes to the 2008 DMP Update EIR.
This Addendum has analyzed all available relevant information to determine whether there is new
information that was not available at the time the 2008 DMP Update EIR was certified, indicating that a
new significant effect not reported in that document may occur. Based on the information and analyses
above, there is no substantial new information indicating that there would be a new significant impact
related to visual resources requiring major revisions to the 2008 DMP Update EIR.
The 2008 DMP Update EIR did not identify any potentially significant impacts to visual resources, and no
new information, mitigation, or alternatives to the project have been identified that would substantially
reduce one or more significant impacts pertaining to visual resources.
With regards to potential visual resources impacts, the New and Revised Project Components are within
the scope of the 2008 DMP Update EIR. None of the conditions under Section 15162 requiring a
subsequent EIR have been met.
3.6 TRANSPORTATION/CIRCULATION
3.6.1 Previous Analysis
The analysis of the impacts related to transportation/circulation for the 2008 DMP Update is contained
in the 2008 DMP Update EIR, Section 4.4, pages 4.4-1 to 4.4-8. Cumulative impacts related to
transportation/circulation are discussed in Section 5.2.1.4 on pages 5-12 to 5-13 of the 2008 DMP
Update EIR. With respect to the programmatic evaluation of the impacts of the PLDA Project
Components, the EIR made the following conclusions:
1) Short-term traffic impacts would occur during construction; however, the principal traffic
impacts during the implementation of 2008 DMP Update project components would occur for
those project components where construction would be required to install or replace facilities
within existing roadways. Other project components would require construction across
roadways. As part of the identified construction practices, implementation of the required
traffic control measures in the traffic control plans would avoid traffic-related impacts due to
lane closures. The provision of roadway detours as needed and use of signage would minimize
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CIP Project No. 6623
Addendum 3-22 January 2026
congestion and provide emergency access at all times. Potential impacts would be less than
significant and no mitigation is required.
2) Construction, operation, and maintenance activities would generate truck traffic for the import
and removal of materials and equipment from project sites, as well as light vehicle traffic for
commuting work crews. All traffic impacts would be short term and the volume of traffic is not
expected to exceed 200 peak hour trips per hour or increase traffic on roadways to a level that
would result in the degradation of level of service at intersections or on roadway segments. A
detailed traffic control plan would be implemented as part of project design to provide
adequate measures to ensure public safety of motorists and pedestrians located near proposed
construction areas. Potential impacts would be less than significant and no mitigation is
required.
3.6.2 Analysis of the Project Changes
3.6.2.1 Direct and Indirect Impacts
As described in Section 2.0, Project Description, all of the new project components fall within the
description of the types of projects identified in Section 3.3.2 of the 2008 DMP Update EIR, and the
nature of work is consistent with the project design features/methods and construction activities
described in Section 3.3.5 of the 2008 DMP Update EIR. Furthermore, no changes are proposed to the
revised project components that would result in project components that are inconsistent with the
descriptions in Sections 3.3.2 and 3.3.5 of the 2008 DMP Update EIR. As described in the 2008 DMP
Update EIR and in Table 3-6 (included in Appendix C of this Addendum), a detailed traffic control plan is
incorporated as part of the project design and includes signage and flaggers, and other warning devices
to allow heavy equipment on roadways, and would provide adequate measures to ensure public safety
of motorists and pedestrians located near proposed construction areas. No changes to the impact
determination in the 2008 DMP Update EIR presented in Section 3.6.1 of this Addendum are required;
impacts would be less than significant and no mitigation is required.
3.6.2.2 Cumulative Impacts
As is the case for the 2008 DMP Update, implementation of New or Revised Project Components would
result in short-term traffic impacts; however, cumulative short-term construction-related traffic impacts
generated in conjunction with other development projects would be minimized through coordination
and implementation of traffic control plans at the time of construction with the City Engineering
Department. As stated in Section 5.2.1.4 (page 5-13) of the 2008 DMP Update EIR, the process for
obtaining Encroachment Permits, which are required for all construction affecting public rights-of-way in
the City, is designed to reduce direct and cumulative short-term construction traffic impacts to below a
level of significance. Because no long-term trips are associated with the project components,
implementation of the New or Revised Project Components would not contribute to a cumulatively
significant transportation impact.
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
January 2026 3-23 Addendum
3.6.3 Substantial Changes with Respect to Circumstances or New Information of Substantial
Importance
3.6.3.1 Update to Transportation Impact Assessment Methodology
As noted in Section 3.2, Addendum Methodology, this Addendum analysis addresses the same
environmental categories evaluated in the 2008 DMP Update EIR, using equivalent methodology. Since
the adoption of the 2008 DMP Update EIR, changes to CEQA and the State CEQA Guidelines introduced a
new methodology for evaluating impacts associated with transportation based on vehicle miles traveled
(VMT). Although this Addendum applies the same methodology and thresholds as the 2008 DMP Update
EIR, the updated regulations and guidance were reviewed in the context of the project to confirm that
the regulatory change does not represent a substantial change with respect to circumstances or new
information of substantial importance.
In accordance with updates to CEQA and the State CEQA Guidelines Section 15064.3(a), the City
currently evaluates impacts to transportation based on VMT. VMT refers to the amount and distance of
automobile travel attributable to a project. Specifically, State CEQA Guidelines Section 15064.3,
Subdivision (b) states that for land use projects, transportation impacts are to be measured by
evaluating the project’s VMT, as outlined in the following:
Vehicle miles traveled exceeding an applicable threshold of significance may indicate a
significant impact. Generally, projects within one-half mile of either an existing major
transit stop or a stop along an existing high quality transit corridor should be presumed
to cause a less than significant transportation impact. Projects that decrease vehicle
miles traveled in the project area compared to existing conditions should be presumed to
have a less than significant transportation impact.
VMT is the amount and distance of automobile travel attributable to a project. According to the 2018
Governor’s Office of Planning and Research’s3 (OPR) Technical Advisory, “automobile” refers to “on-road
passenger vehicles, specifically cars and light trucks.” Thus, construction trucks do not need to be
included in the VMT assessment for the Proposed Changes.
Additionally, the OPR Technical Advisory and the City of Carlsbad Vehicle Miles Traveled (VMT) Analysis
Guidelines (May 31, 2023) recommend VMT screening thresholds for smaller projects. These documents
recommend that a project generating 110 average daily trips (ADT) or less be screened out of a VMT
analysis due to the presumption of a less than significant impact.
The proposed project would generate both passenger vehicle and truck trips on a temporary basis for
construction. Excluding construction trucks, the proposed project is likely to generate nominal
passenger vehicle ADT (fewer than 110) for temporary construction. In addition, the proposed project
would not generate any new passenger vehicle trips during day-to-day operations since there would not
be any full-time dedicated staff on site. As such, the New or Revised Project Components are considered
small projects and presumed to have a less than significant impact on transportation. Therefore, the
Project Changes would not conflict or be inconsistent with State CEQA Guidelines Section 15064.3(b).
3 Effective July 1, 2024, this office has been renamed the Office of Land Use and Climate Innovation.
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CIP Project No. 6623
Addendum 3-24 January 2026
3.6.3.2 Determination
Based on the above information, using the VMT approach to evaluating transportation/circulation
impacts does not result in the identification of new information of substantial importance or a
substantial change with respect to the circumstances under which the project is being undertaken.
No other substantial changes have occurred with respect to the circumstances under which the project
is being undertaken and no new information of substantial importance has been identified with regard
to transportation/circulation.
3.6.4 Conclusion
Based on the foregoing analysis and information, there is no evidence that the New or Revised Project
Components require a major change to the 2008 DMP Update EIR. The Project Changes would not result
in new significant environmental impacts related to transportation and circulation, and there would not
be a substantial increase in the severity of impacts as described in the 2008 DMP Update EIR or using
the current VMT standard of analysis. Implementation of the project design features/methods and
construction measures identified in Table 3-6 of the 2008 DMP Update EIR (included in Appendix C of
this Addendum) would ensure that temporary and permanent impacts would remain less than
significant and no mitigation is required.
No major changes to the project area or the general scope and magnitude of the project components
have taken place since preparation of the 2008 DMP Update EIR that would require revisions to the
analysis in the EIR. There is no information in the record or otherwise available that indicates that there
are substantial changes in circumstances pertaining to transportation and circulation that would require
major changes to the 2008 DMP Update EIR.
This Addendum has analyzed all available relevant information to determine whether there is new
information that was not available at the time the 2008 DMP Update EIR was certified, indicating that a
new significant effect not reported in that document may occur. Based on the information and analyses
above, there is no substantial new information indicating that there would be a new significant impact
related to transportation and circulation requiring major revisions to the 2008 DMP Update EIR.
The 2008 DMP Update EIR did not identify significant impacts pertaining to transportation and
circulation, and no new information, mitigation, or alternatives to the project have been identified that
would substantially reduce one or more significant impacts pertaining to transportation and circulation.
With regards to transportation/circulation impacts, the New and Revised Project Components are within
the scope of the 2008 DMP Update EIR. None of the conditions under Section 15162 requiring a
subsequent EIR have been met.
3.7 AIR QUALITY
3.7.1 Previous Analysis
The analysis of the impacts to air quality for the 2008 DMP Update is contained in the 2008 DMP Update
EIR, Section 4.5, pages 4.5-1 to 4.5-12. Cumulative impacts related to land use are discussed in Section
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January 2026 3-25 Addendum
5.2.1.5 on page 5-13 of the 2008 DMP Update EIR. With respect to the programmatic evaluation of the
impacts of the PLDA Project Components, the EIR made the following conclusions:
1) The principal sources of gaseous emissions and some particulate emissions would be the engine
exhaust of diesel engine-driven construction equipment. Principal sources of particulate emissions
would be grading and soil disturbance, and vehicle operations on unpaved and paved surfaces.
Emissions would be minimized by the implementation of identified design and construction
practices. There would be a potential for emissions of odors from disturbance of wet sediments or
from paving activities. If these odors occurred, they would dissipate relatively rapidly and would
not be anticipated to be noticeable for more than one week due to the anticipated construction
schedule. Potential impacts would be less than significant and no mitigation is required.
2) With the implementation of the identified design and construction practices, emissions would
not be of a magnitude to conflict with existing attainment and maintenance plans, violate air
quality standards, or make a considerable contribution to the existing regional pollutant
concentrations. The construction, operations and maintenance activities would not expose
sensitive receptors to substantial pollutant concentrations, nor would there be objectionable
odors that would affect sensitive receptors for an extended period of time. Potential impacts
would be less than significant and no mitigation is required.
3.7.2 Analysis of the Project Changes
Section 4.5.1.1 of the 2008 DMP Update EIR presents information related to the existing setting for the
2008 DMP Update. Updated information is available related to the attainment status of the San Diego
Air Basin (SDAB) and the ambient air quality in the vicinity of the project.
Both State and federal governments have established health-based ambient air quality standards
(AAQS) for six criteria air pollutants: carbon monoxide (CO), ozone (O3), nitrogen dioxide (NO2), sulfur
dioxide (SO2), lead (Pb), and suspended particulate matter (PM). In addition, the State has set standards
for sulfates, hydrogen sulfide, vinyl chloride, and visibility-reducing particles. These standards are
designed to protect the health and welfare of the populace with a reasonable margin of safety. Long-
term exposure to elevated levels of criteria pollutants may result in adverse health effects. However,
emission thresholds established by an air quality district are used to manage total regional emissions
within an air basin based on the air basin’s attainment status for criteria pollutants. These emission
thresholds were established for individual projects that would contribute to regional emissions and
pollutant concentrations and could adversely affect or delay the projected attainment target year for
certain criteria pollutants.
Air quality monitoring stations are located throughout the nation and maintained by the local air
districts and State air quality regulating agencies. Data collected at permanent monitoring stations are
used by the United States Environmental Protection Agency (USEPA) to identify regions as “attainment”
or “nonattainment” depending on whether the regions meet the requirements stated in the applicable
National Ambient Air Quality Standards (NAAQS). Nonattainment areas are subject to additional
restrictions as required by the USEPA. In addition, different classifications of attainment, such as
marginal, moderate, serious, severe, and extreme, are used to classify each air basin in the State on a
pollutant-by-pollutant basis. The classifications are used as a foundation to create air quality
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Addendum 3-26 January 2026
management strategies to improve air quality and comply with the NAAQS. Table F lists attainment
statuses for each of the criteria pollutants for San Diego County.
The 2008 DMP Update EIR identified the closest ambient air quality monitoring station to the project
site as the Del Mar-Mira Costa College Monitoring Station. Table 4.5-2 on page 4.5-5 of the 2008 DMP
Update EIR presents the ambient air quality summary at that station from 2001 through 2005. At
present, the ambient air quality monitoring station closest to the City is located approximately 6 miles
north from the closest project area at 21441-W B Street in Camp Pendleton. This monitoring station
represents the collective air quality for the coastal region of North County San Diego and represents the
Table F: Attainment Status of Criteria Pollutants in San Diego County
Pollutant Federal (as of 2024) State (as of 2024)
O3 1 hour Attainment Nonattainment
O3 8 hour Nonattainment1 Nonattainment
CO Attainment Attainment
PM10 Unclassifiable2 Nonattainment
PM2.5 Attainment Nonattainment
NO2 Attainment Attainment
SO2 Attainment Attainment
Pb Attainment Attainment
Sulfates No Federal Standard Attainment
Hydrogen Sulfide No Federal Standard Unclassified
Visibility No Federal Standard Unclassified
Source: Attainment Status (San Diego Air Pollution Control District 2025).
1 The federal 1-hour standard of 12 ppm was in effect from 1979 through June 15, 2005. The revoked standard is referenced here because
it was employed for such a long period and because this benchmark is addressed in State Implementation Plans.
2 At the time of designation, if the available data do not support a designation of attainment or nonattainment, the area is designated as
unclassifiable.
CO = carbon monoxide
NO2 = nitrogen dioxide
O3 = ozone
Pb = lead
PM10 = particulate matter less than 10 microns in diameter
PM2.5 = particulate matter less than 2.5 microns in diameter
ppm = parts per million
SO2 = sulfur dioxide
best available data for criteria pollutants nearest the City. Pollutant monitoring results for years 2021 to
2023 were available at the 21441-W B Street ambient air quality monitoring station. Table G provides an
update to Table 4.5-2 in the 2008 DMP Update EIR, including recent data from relevant monitoring
stations. The results presented in Table G indicate that air quality in the City’s vicinity has generally been
good overall. No data were available for State and federal PM10 (respirable particulate matter) standards
from 2021 through 2023. There were no data for State and federal PM2.5 (fine particulate matter)
standards between 2021 and 2020; however, there were no exceedances in 2023. Further, State 1-hour
ozone standards were not exceeded during the 3-year period. Similarly, the State and federal 8-hour
ozone standards were not exceeded from 2021 to 2022 but had one exceedance in 2023. The federal 1-
hour and 8-hour CO standards had no exceedances for all 3 years. Lastly, the State and federal NO2
standards were also not exceeded in this area during the 3-year period.
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January 2026 3-27 Addendum
Table G: Ambient Air Quality Summary in the Project Vicinity
Pollutant Standard 2021 2022 2023
CO (Measured at the El Cajon-Lexington Elementary School Monitoring Station)1
Maximum 1-hour concentration (ppm) 1.2 1.4 1.1
No. of days exceeded State: 20 ppm ND ND ND
Federal: 35 ppm 0 0 0
Maximum 8-hour concentration (ppm) 1.1 1.1 0.9
No. of days exceeded State: 9 ppm ND ND ND
Federal: 9 ppm 0 0 0
O3 (Measured at the Camp Pendleton Monitoring Station)2
Maximum 1-hour concentration (ppm) 0.074 0.076 0.090
No. of days exceeded State: 0.09 ppm 0 0 0
Max 8-hr concentration (ppm) 0.59 0.067 0.077
No. of days exceeded State: 0.07 ppm 0 0 1
Federal: 0.07 ppm 0 0 1
PM10 (Measured at the Camp Pendleton Monitoring Station)2
Maximum 24-hour concentration (μg/m3) ND ND ND
No. of days exceeded State: 50 μg/m3 ND ND ND
Federal: 150 μg/m3 ND ND ND
Annual avg. concentration (μg/m3) ND ND ND
Exceeds Standard? State: 20 μg/m3 ND ND ND
PM2.5 (Measured at the Camp Pendleton Monitoring Station)2
Maximum 24-hour concentration (μg/m3) ND 17.0 26.5
No. of days exceeded Federal: 35 μg/m3 ND 0 0
Annual avg. concentration (μg/m3) ND ND 7.8
Exceeds Standard? State: 12 μg/m3 ND ND No
Federal: 12 μg/m3 ND ND No
NO2 (Measured at Camp Pendleton Monitoring Station)2
Maximum 1-hour concentration (ppb): 0.0590 0.0504 0.0632
No. of days exceeded State: 180 ppb 0 0 0
Federal: 100 ppb 0 0 0
Annual avg. concentration (ppb): 0.006 0.005 0.005
Exceeds standard? State: 30 ppb No No No
Federal: 53 ppb No No No
Sources: Air Data: Air Quality Data Collected at Outdoor Monitors across the U.S. (United States Environmental Protection Agency 2024);
and CARB’s iADAM: Air Quality Data Statistics. Website: www.arb.ca.gov/adam (accessed October 2024).
1 The El Cajon-Lexington Elementary School Air Quality Monitoring Station is located at 533 First Street.
2 The Camp Pendleton Air Quality Monitoring Station is located at 21441-W B Street.
μg/m3 = micrograms per cubic meter
CARB = California Air Resources Board
CO = carbon monoxide
NO2 = nitrogen dioxide
ND = No available data.
O3 = ozone
PM2.5 = particulate matter smaller than 2.5 microns in size
PM10 = particulate matter smaller than 10 microns in size
ppb = parts per billion
ppm = parts per million
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3.7.2.1 Direct and Indirect Impacts
As with the project components previously included in the 2008 DMP Update, air quality impacts
associated with the New and Revised Project Components would be temporary and associated with
construction activities. Similar to the 2008 DMP Update, operation and maintenance of existing and
proposed drainage facilities would require the use of various pieces of construction equipment and
trucks. Maintenance vehicle trips would only occur when periodic maintenance is required. Thus, the
proposed project would not result in a significant increase in the generation of vehicle trips that would
increase air pollutant emissions. Maintenance vehicle emissions would be minimal and would not
exceed the pollutant thresholds established by the San Diego County Air Pollution Control District
(SDAPCD).
The project would not be a source of stationary source emissions. All of the new project components fall
within the description of the types of projects identified in Section 3.3.2 of the 2008 DMP Update EIR,
and the nature of work is consistent with the project design features/methods and construction
activities described in Section 3.3.5 of the 2008 DMP Update EIR. Furthermore, no changes are proposed
to the revised project components that would result in project components that are inconsistent with
the descriptions in Sections 3.3.2 and 3.3.5 of the 2008 DMP Update EIR.
The 2008 DMP Update EIR states that the SDAPCD has no quantitative emissions criteria for CEQA
evaluations, and therefore, the USEPA thresholds were used for assessment of conformity of federal
projects to the State air quality plans. The 2008 DMP Update EIR found that construction emissions as a
result of the proposed DMP Update project components would be considerably less than the threshold
values. It was determined that emissions would not be of a magnitude to conflict with existing
attainment and maintenance plans, violate air quality standards, or make a considerable contribution to
the existing regional pollutant concentration.
An analysis of project consistency with applicable air quality plans has been included in this Addendum
for the New or Revised Project Components in accordance with current standards of review. An air
quality plan describes air pollution control strategies to be implemented by a city, county, or region
classified as a non-attainment area. The SDAPCD is responsible for developing and implementing the
clean air plans for attainment and maintenance of the AAQS in the SDAPCD specifically, the State
Implementation Plans (SIP) and the San Diego Regional Air Quality Strategy (RAQS). The federal O3
maintenance plan, which is part of the SIP, was adopted in 2012. The most recent O3 attainment plan
was adopted in 2022. The SIP includes a demonstration that current strategies and tactics will maintain
acceptable air quality in the SDAB based on the NAAQS. The RAQS was initially adopted in 1992 and is
updated on a triennial basis (most recently in 2022). The RAQS outlines SDAPCD plans and control
measures primarily for stationary sources to attain the State’s air quality standards for O3. The SIP and
RAQS rely on information from the California Air Resources Board (CARB) and San Diego Association of
Governments (SANDAG), including mobile and area source emissions, as well as information regarding
projected growth in the County as a whole and the cities in the County, to project future emissions and
determine the strategies necessary for the reduction of emissions through regulatory controls. CARB
mobile source emission projections and SANDAG growth projections are based on population, vehicle
trends, and land use plans developed by the County and the cities in the County as part of the
development of their general plans.
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January 2026 3-29 Addendum
Projects that propose development that is consistent with the growth anticipated by the general plans
would be consistent with the RAQS. In the event that a project would propose development that is less
dense than anticipated by the General Plan, the project would likewise be consistent with the RAQS. If a
proposed project involves development that is greater than that anticipated in the local plan and
SANDAG’s growth projections, the project might be in conflict with the SIP and RAQS, and the project
may contribute to a potentially significant cumulative impact on air quality.
The proposed Project Changes are designed to accomplish the following:
x Address existing and anticipated future drainage infrastructure deficiencies within the City at a
basin-wide level;
x Provide facilities to accommodate storm flows from future development contemplated by the City’s
General Plan;
x Provide facilities to accommodate anticipated drainage infrastructure needs in the City, either
through rehabilitation and replacement of aging infrastructure or implementation of new facilities
necessary to accommodate generalized future development; and
x Provide for necessary long-term infrastructure operation and maintenance activities to ensure
public safety, reduction of flood hazards, and storm water quality control.
Based on the nature of the New and Revised Project Components and as described in Section 3.1 of this
Addendum, the proposed Project Changes would not conflict with existing zoning or General Plan land
use designations for the project site. Therefore, the proposed project would not conflict with the
applicable Air Quality Plans.
No changes to the impact conclusions in the 2008 DMP Update EIR presented in Section 3.7.1 are
needed; impacts would be less than significant and no mitigation is required.
3.7.2.2 Cumulative Impacts
Air pollution control within the region is the responsibility of the SDAPCD, which applies rules and
regulations throughout the region. Development and existing uses within the City and surrounding area
will contribute to short-term and long-term cumulative impacts to air quality. Implementation of the
New or Revised Project Components would be limited to short-term effects resulting from construction,
and would be minimized by incorporation of the dust control and construction emissions control
features included in Table 3-6 (included in Appendix C of this Addendum). Implementation of the New or
Revised Project Components would not contribute to impacts in excess of what was envisioned for the
2008 DMP Update. As stated in Section 5.2.1.5 (page 5-13) of the 2008 DMP Update EIR, the short-term
air quality impacts from project components would not result in a significant contribution to cumulative
air quality impacts, as they would be minimized consistent with SDAPCD requirements.
3.7.3 Substantial Changes with Respect to Circumstances or New Information of Substantial
Importance
As presented in Section 3.6.2, updated information is available related to the attainment status of the
SDAB and the ambient air quality in the vicinity of the project. In keeping with current professional
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Addendum 3-30 January 2026
standards of review, this updated information has been included in this Addendum, along with an
evaluation of consistency with adopted plans. This information does not represent a substantial change
or provide new information of substantial importance. No other substantial changes have occurred with
respect to the circumstances under which the project is being undertaken and no new information of
substantial importance has been identified with regard to air quality.
As presented in Section 3.2, New and Revised Project Components are consistent with the City’s CAP
Update, which incorporated the City’s Strategic Plan (2022) and thereby also the DMP. The Project
Changes would not result in substantially different GHG emissions or otherwise conflict with CAP
provisions.
3.7.4 Conclusion
Based on the foregoing analysis and information, there is no evidence that the New or Revised Project
Components require a major change to the 2008 DMP Update EIR. The Project Changes would not result
in new significant environmental impacts related to air quality, and there would not be a substantial
increase in the severity of impacts described in the 2008 DMP Update EIR. Implementation of the
project design features/methods and construction measures identified in Table 3-6 of the 2008 DMP
Update EIR (included in Appendix C of this Addendum) would ensure that temporary and permanent
impacts would remain less than significant and no mitigation is required.
No major changes to the project area or the general scope and magnitude of the project components
have taken place since preparation of the 2008 DMP Update EIR that would require revisions to the
analysis in the EIR. There is no information in the record or otherwise available that indicates that there
are substantial changes in circumstances pertaining to air quality that would require major changes to
the 2008 DMP Update EIR.
This Addendum has analyzed all available relevant information to determine whether there is new
information that was not available at the time the 2008 DMP Update EIR was certified, indicating that a
new significant effect not reported in that document may occur. Based on the information and analyses
above, there is no substantial new information indicating that there would be a new significant impact
related to air quality requiring major revisions to the 2008 DMP Update EIR.
The 2008 DMP Update EIR did not identify any significant impacts to air quality, and no new
information, mitigation, or alternatives to the project have been identified that would substantially
reduce one or more significant impacts pertaining to air quality.
With regards to potential air quality impacts, the New and Revised Project Components are within the
scope of the 2008 DMP Update EIR. None of the conditions under Section 15162 requiring a subsequent
EIR have been met.
3.8 NOISE
3.8.1 Previous Analysis
The analysis of the impacts to noise for the 2008 DMP Update is contained in the 2008 DMP Update EIR,
Section 4.6, pages 4.6-1 to 4.6-15. Cumulative impacts related to noise are discussed in Section 5.2.1.6
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January 2026 3-31 Addendum
on pages 5-13 and 5-14 of the 2008 DMP Update EIR. With respect to the programmatic evaluation of
the impacts of the PLDA Project Components, the EIR made the following conclusions (Mitigation
Measures are included in Appendix C of this Addendum for reference):
1) Impact Noise-1: There would be a potentially significant noise impact if construction or
operation and maintenance of a proposed 2008 DMP Update component would require the use
of heavy equipment, generating noise of 75 A-weighted decibels (dBA) or greater within 50 feet
of a sensitive receptor for a period of longer than three days, or if a proposed 2008 DMP Update
component would require work to be done after sunset or before 7:00 a.m.
With implementation of Mitigation Measure Noise-1, residual impacts would be less than
significant with mitigation incorporated.
2) Impact Noise-2: There would be a potentially significant vibration impact if a proposed 2008
DMP Update component would require the use of pile drivers, generating a vibration of
0.2 inches per second (in/sec) or greater at any nearby structures.
With implementation of Mitigation Measure Noise-2, residual impacts would be less than
significant with mitigation incorporated.
3.8.2 Analysis of the Project Changes
3.8.2.1 Direct and Indirect Impacts
As with the project components previously included in the 2008 DMP Update, noise and vibration
impacts associated with the New and Revised Project Components would be temporary, associated with
construction activities or occasional operations and maintenance. All of the new project components fall
within the description of the types of projects identified in Section 3.3.2 of the 2008 DMP Update EIR,
and the nature of work is consistent with the project design features/methods and construction
activities described in Section 3.3.5 of the 2008 DMP Update EIR. Furthermore, no changes are proposed
to the revised project components that would result in project components that are inconsistent with
the descriptions in Sections 3.3.2 and 3.3.5 of the 2008 DMP Update EIR.
Noise. Table 4.6-3 (page 4.6-9) in the 2008 DMP Update EIR presents the noise levels from typical
construction equipment, followed by an assessment of noise impacts from construction of project
components. The evaluation of construction noise impacts associated with the New or Revised Project
Components has been updated in accordance with current professional practice and to reflect a change
to the Carlsbad Municipal Code Noise Ordinance (City of Carlsbad 2025).
As discussed in the 2008 DMP Update EIR, construction equipment would be the principal source of
noise during implementation of project components. For most equipment, such as bulldozers, trucks,
loaders, and scrapers, the diesel engines of the equipment would be the loudest noise source.
If jackhammers or other sorts of pavement breakers are used, the noise of the impact tool would be
dominant. Table H shows some typical maximum noises at a distance of 50 feet from the equipment.
Noise from two or more pieces of equipment would be greater than for one piece of equipment.
Average noise levels would be less than maximum noise levels because equipment does not operate at
full power all of the time, nor does it always stay in one location. With these considerations, an average
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Addendum 3-32 January 2026
noise level of 80 dBA equivalent noise level (Leq) at a distance of 50 feet is a conservative value for these
projects, assuming pile drivers would not be required during construction of the proposed projects.
Construction equipment may be considered a point source, with noise attenuation (reduction) of 6 dBA
for each doubling of distance from the source. Thus, a noise level of 80 dBA at 50 feet would be 74 dBA
at 100 feet, 68 dBA at 200 feet, etc.
Table H: Typical Construction Equipment Noise Levels (dBA)
Equipment Description Acoustical Usage Factor (%)
Maximum Noise Level (Lmax)
at 50 Feet1
Compressor 40 80
Cranes 16 85
Dozers 40 85
Drill Rig 20 84
Flat Bed Trucks 40 84
Forklift 20 85
Front-end Loaders 40 80
Generator 50 82
Grader 40 85
Jackhammer 20 85
Impact Pile Driver 20 95
Man-lift 20 85
Rollers 20 85
Scraper 40 85
Water Truck 40 84
Welder 40 73
Source: Roadway Construction Noise Model (FHWA 2006).
Note: Noise levels reported in this table are rounded to the nearest whole number.
1 Maximum noise levels were developed based on Specification 721.560 from the Central Artery/Tunnel program to
be consistent with the City of Boston’s Noise Code for the “Big Dig” project.
FHWA = Federal Highway Administration
Lmax = maximum instantaneous sound level
As described in the 2008 DMP Update EIR, many project components would be linear in nature and the
noise at adjacent residences or sensitive land uses would be loudest for only a period of hours. Many
would be located more than 90 feet from sensitive receptors, and noise levels would not be anticipated
to exceed 75 dBA Leq averaged over 1 hour. Therefore, potentially significant impacts would be limited
to those projects with a relatively small area of work, duration of more than a few days, and a location
near sensitive receptors. There would also be a potentially significant impact for any component that
would require the use of pile drivers. However, noise impacts would be minimized by the
implementation of project design features/methods and construction practices in Table 3-6 of the 2008
DMP Update EIR (included in Appendix C of this Addendum).
While the noise standards have not changed since the completion of the 2008 DMP Update EIR, the
construction noise assessment has resulted in a refinement of the distance at which the 75 dBA Leq noise
level is expected to be exceeded. It was previously identified that 75 dBA is likely to occur at a distance
of 50 feet, updated calculations using currently-accepted models and typical noise levels show that the
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January 2026 3-33 Addendum
75 dBA noise level could occur within up to 90 feet of construction activities. This updated analysis does
not indicate an increase in noise impacts; rather, it affects the distance to sensitive receptors to ensure
that impacts remain less than significant. Based on the updated analysis, Impact Noise-1 should be
revised as follows:
There would be a potentially significant noise impact if construction or operation and
maintenance of a proposed 2008 DMP Update component would require the use of
heavy equipment, generating noise of 75 dBA or greater within 50 90 feet of a sensitive
receptor for a period of longer than 3 days, or if a proposed 2008 DMP Update
component would require work to be done after sunset or before 7:00 a.m.
A corresponding revision to Mitigation Measure Noise-1 would ensure that impacts related to
construction noise are less than significant as shown here:
Mitigation Measure Noise-1 If a proposed project component would require the use of construction
equipment that may generate noise of 75 dBA within 50 90 feet of a
sensitive receptor for a period of longer than 3 days, or would require
work to be done between sunset and 7:00 a.m., as permitted by
Municipal Code Section 8.48.020, preparation and implementation of a
project level noise evaluation shall be required. The evaluation shall
assess potential noise levels and require the implementation of
appropriate noise attenuation measures to reduce potential noise
impacts to less than 75 dBA Leq during the daytime or to 60 dBA Leq at
nighttime. The noise evaluation shall consider the use of temporary
noise walls, noise blankets, noise-reducing enclosures for individual
pieces of equipment, and engines with special mufflers as potential
noise attenuation measures. Monitoring shall be required to
demonstrate the effectiveness of the project-specific measures to
reduce noise levels to this limit. If monitoring results indicate that the
measures are not reducing noise to acceptable levels, work will cease
until further environmental analysis is performed that recommends
additional noise attenuation measures. For emergency projects as
defined in Municipal Code Section 8.48.020(A), the requirement for
evaluation, monitoring, and potential additional mitigation measures
shall be performed if determined feasible by the City Engineer.
With incorporation of the minor revisions noted above, no additional changes are needed to the impact
determinations in the 2008 DMP Update EIR presented in Section 3.8.1, and Impact Noise-1 would be
less than significant with mitigation incorporated.
Vibration. Table 4.6-4 (page 4.6-11) in the 2008 DMP Update EIR presents ground vibration levels
associated with various types of construction equipment, and Table 4.6-5 (page 4.6-11) presents the
vibration level thresholds for architectural and structural damage and human perception thresholds.
These are followed by a discussion of the vibration impacts associated with construction of DMP project
components. The evaluation of construction vibration impacts associated with the New or Revised
Project Components has been updated in accordance with current professional practice.
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Table I summarizes ground vibration levels associated with various types of construction equipment,
based on currently available information.
Table I: Representative Vibration Source Levels for Typical
Construction Equipment
Equipment
Reference PPV (in/sec) at
25 feet
Pile Driver (impact, upper range) 1.518
(impact, typical) 0.644
Hoe Ram 0.089
Large Bulldozer 0.089
Caisson Drilling 0.089
Loaded Trucks 0.076
Jackhammer 0.035
Small Bulldozer 0.003
Source: Transit Noise and Vibration Impact Assessment Manual (FTA 2018).
FTA = Federal Transit Administration
in/sec = inches per second
PPV = peak particle velocity
No update is needed for Table 4.6-5 in the 2008 DMP Update EIR, which identifies the reaction of people
and damage to buildings at various continuous vibration levels. However, the Transit Noise and
Vibration Impact Assessment Manual (Federal Transit Administration [FTA] 2018) provides additional
information regarding the criteria for environmental impact from groundborne vibration and noise,
based on the maximum levels for a single event. Table J lists the potential vibration building damage
criteria associated with construction activities.
Table J: Construction Vibration Damage Criteria
Building Category PPV (in/sec)
Reinforced concrete, steel, or timber (no plaster) 0.50
Engineered concrete and masonry (no plaster) 0.30
Non-engineered timber and masonry buildings 0.20
Buildings extremely susceptible to vibration damage 0.12
Source: Transit Noise and Vibration Impact Assessment Manual (FTA 2018).
FTA = Federal Transit Administration
in/sec = inch/inches per second
PPV = peak particle velocity
FTA guidelines shows that a vibration level of up to 0.5 in/sec in peak particle velocity (PPV) (FTA 2018)
is considered safe for buildings consisting of reinforced concrete, steel, or timber (no plaster) and would
not result in any construction vibration damage. For a non-engineered timber and masonry building, the
construction building vibration damage criterion is 0.2 in/sec PPV. Additionally, a level of 0.2 in/sec PPV
is considered the threshold of annoyance to people in buildings.
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January 2026 3-35 Addendum
It is determined from Tables I and J that, if no pile driving is performed and the work is more than
25 feet from a receptor, then the vibration would be less than half of the 0.2 in/sec PPV threshold used
by the FTA. This determination is consistent with the 2008 DMP Update EIR, and no changes are needed
to the Impact Noise-2 conclusion in Section 3.8.1 or to the corresponding Mitigation Measure Noise-2
(included in Appendix C of this Addendum). Impacts would be less than significant with mitigation
incorporated.
3.8.2.2 Cumulative Impacts
As with the project components in the 2008 DMP Update, noise impacts associated with the New or
Revised Project Components would be limited to short-term impacts associated with construction.
Cumulative noise impacts in the City are generally related to long-term increases in traffic and the
addition of long-term point sources. Although the New or Revised Project Components could
temporarily generate noise in localized areas, the contribution to the overall noise environment would
not be substantial. Mitigation Measures Noise-1 (as revised) and Noise-2 would further reduce these
impacts to the extent feasible. Consistent with the conclusion in Section 5.2.1.6 of the 2008 DMP
Update EIR, the project components would not result in a significant contribution to cumulative noise
impacts.
3.8.3 Substantial Changes with Respect to Circumstances or New Information of Substantial
Importance
The 2008 DMP Update EIR indicated that the City’s Noise Ordinance in CMC Section 8.48.020 does not
specifically allow an exception to the hours of construction for non-emergency work or work within
1,000 feet of a residence. Since certification of the EIR, the Noise Ordinance has been amended (City of
Carlsbad 2025). Municipal Code Section 8.48.020(B) now states:
The building official, city engineer, or other official designated by the city manager may
modify the hours of construction specified in Section 8.48.010. In making a
determination to lengthen or shorten the hours of construction, the city official shall
consider the following: 1. Whether the project is an emergency repair required to protect
the health and safety of any member of the community; 2. Whether the construction
would be less objectionable at night than during daylight hours; 3. The character and
nature of the neighborhood in the vicinity of the work site; 4. The potential for great
economic hardship; 5. If the work is in the interest of the general public; 6. Whether
there is a previously unforeseen effect on the health, safety or welfare of the public;
and 7. Any history of complaints regarding compliance with the limitation on hours of
construction.
The revision to the Noise Ordinance would reduce the potential for construction activities to be in
conflict with the City’s municipal code in the event that nighttime construction is required. Therefore,
there would be no change in the severity of the impact and this does not represent new information of
substantial importance or substantial changes to the circumstances under which the project is
undertaken, but is rather a clarification of the current updated Noise Ordinance language.
As discussed in Section 3.8.2, the updated assessment of noise impacts resulted in a refinement to the
distance at which construction noise could exceed 75 dBA, requiring a revision to Impact Noise-1.
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Mitigation Measure Noise-1 requires a project-level noise analysis for construction activities that have
the potential to result in substantial impacts to identify appropriate noise attenuation measures.
Refining the criteria within this measure to include projects that may be within 90 feet (rather than
50 feet) of a sensitive receptor is sufficient to ensure that construction-related noise impacts would be
less than significant. This would not require a mitigation measure that is considerably different from
Mitigation Measure Noise-1 included in the 2008 DMP Update EIR; furthermore, the refinement to the
distance at which unmitigated noise levels could exceed acceptable levels does not represent a new
significant impact or a substantial increase in the severity of an impact as defined in State CEQA
Guidelines Section 15165. The noise impacts are not increasing; rather, it is the distance to sensitive
receptors that has been extended to ensure that impacts would remain less than significant.
No other substantial changes with respect to the circumstances under which the project is being
undertaken and no new information of substantial importance have been identified with regards to
noise or vibration.
3.8.4 Conclusion
Based on the foregoing analysis and information, there is no evidence that the New or Revised Project
Components require a major change to the 2008 DMP Update EIR. The Project Changes would not result
in new significant environmental impacts related to noise, and there would not be a substantial increase
in the severity of impacts described in the 2008 DMP Update EIR. Implementation of the project design
features/methods and construction measures identified in Table 3-6 of the 2008 DMP Update EIR
(included in Appendix C of this Addendum) and Mitigation Measures Noise-1 (as revised) and Noise 2
remain applicable and would ensure that temporary and permanent impacts would remain less than
significant.
No major changes to the project area or the general scope and magnitude of the project components
have taken place since preparation of the 2008 DMP Update EIR that would require revisions to the
analysis in the EIR. There is no information in the record or otherwise available that indicates that there
are substantial changes in circumstances pertaining to noise that would require major changes to the
2008 DMP Update EIR.
This Addendum has analyzed all available relevant information to determine whether there is new
information that was not available at the time the 2008 DMP Update EIR was certified, indicating that a
new significant effect not reported in that document may occur. Based on the information and analyses
above, there is no substantial new information indicating that there would be a new significant impact
related to noise requiring major revisions to the 2008 DMP Update EIR.
There is no new information, mitigation, or alternatives to the project that would substantially reduce
one or more significant impacts pertaining to noise identified and considered in the 2008 DMP Update
EIR. The revisions to Mitigation Measure Noise-1 constitute a minor clarification and do not result in a
mitigation measure that is substantially different from mitigation in the 2008 DMP Update EIR.
With regards to potential noise impacts, the New and Revised Project Components are within the scope
of the 2008 DMP Update EIR. None of the conditions under Section 15162 requiring a subsequent EIR
have been met.
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January 2026 3-37 Addendum
3.9 RECREATION
3.9.1 Previous Analysis
The analysis of the impacts related to recreation for the 2008 DMP Update is contained in the 2008 DMP
Update EIR, Section 4.7, pages 4.7-1 to 4.7-6. Cumulative impacts related to recreation are discussed in
Section 5.2.1.7 on page 5-14 of the 2008 DMP Update EIR. With respect to the programmatic evaluation
of the impacts of the PLDA Project Components, the EIR made the following conclusion:
1) Proposed 2008 DMP Update components would not involve the construction of
recreational components or improvements to existing or proposed recreational
facilities. Construction or operation and maintenance of proposed facilities could
temporarily impact recreational uses within open space and parks. Potential impacts
to parking or facility use would be short term, and alternative recreational facilities
within the City would remain available for use. Existing public trail systems would
remain open during construction or adequate alternative trail routes would remain
available. If necessary, alternative routes and detours would be identified during
project-specific design, in coordination with the City Park Planning Department.
Potential impacts would be less than significant and no mitigation is required.
3.9.2 Analysis of the Project Changes
3.9.2.1 Direct and Indirect Impacts
All of the new project components fall within the description of the types of projects identified in
Section 3.3.2 of the 2008 DMP Update EIR, and the nature of work is consistent with the project design
features/methods and construction activities described in Section 3.3.5 of the 2008 DMP Update EIR.
Furthermore, no changes are proposed to the revised project components that would result in project
components that are inconsistent with the descriptions in Sections 3.3.2 and 3.3.5 of the 2008 DMP
Update EIR. As discussed in the 2008 DMP Update EIR, project components are intended to provide
storm water conveyance and flood control and would generally not involve the construction of
recreational components or modification to existing recreational facilities. Project component BVC-4,
the Marron and Jefferson Multi-Benefit Basin, includes the expansion of an existing detention basin
within Hosp Grove Park (refer to Table B). This component has the potential to conflict with existing
trails within the Hosp Grove Park; impacts to trails or land use, if any, will be analyzed when plans for
discretionary approval are submitted at a later date. It is likely that impacts to trails can be avoided;
however, although one or more trails may require realignment, the expansion of the existing detention
basin within Hosp Grove Park would not adversely affect the open space resources within the park and
would not adversely affect the recreational experience of park users. With respect to the remaining new
and revised project components, while some are located within open space areas that may be used
recreationally, potential impacts associated with construction or maintenance of project components
(including BVC-4) would be short term, and alternative recreational facilities within the City would
remain available for use. No changes to the impact conclusion in the 2008 DMP Update EIR presented in
Section 3.9.1 of this Addendum are required; impacts would be less than significant.
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Addendum 3-38 January 2026
3.9.2.2 Cumulative Impacts
As with the 2008 DMP Update as evaluated in the 2008 DMP Update EIR, no significant direct or indirect
impacts to recreational services would occur with implementation of the New or Revised Project
Components. As a result, the New or Revised Project Components would not contribute to cumulative
impacts to recreational services in the City.
3.9.3 Substantial Changes with Respect to Circumstances or New Information of Substantial
Importance
No changes have been identified with respect to the circumstances under which the Project Changes
would be undertaken, and there is no new information of substantial importance that has become
available relative to recreation.
3.9.4 Conclusion
Based on the foregoing analysis and information, there is no evidence that the New or Revised Project
Components require a major change to the 2008 DMP Update EIR. The Project Changes would not result
in new significant environmental impacts related to recreation, and there would not be a substantial
increase in the severity of impacts described in the 2008 DMP Update EIR. Although no specific project
design features/methods and construction measures were identified with respect to recreation,
implementation of those identified in Table 3-6 of the 2008 DMP Update EIR for land use, visual
resources, and transportation/circulation (included in Appendix C of this Addendum) would ensure that
temporary and permanent impacts would remain less than significant and no mitigation is required.
No major changes to the project area or the general scope and magnitude of the project components
have taken place since preparation of the 2008 DMP Update EIR that would require revisions to the
analysis in the EIR. There is no information in the record or otherwise available that indicates that there
are substantial changes in circumstances pertaining to recreation that would require major changes to
the 2008 DMP Update EIR.
This Addendum has analyzed all available relevant information to determine whether there is new
information that was not available at the time the 2008 DMP Update EIR was certified, indicating that a
new significant effect not reported in that document may occur. Based on the information and analyses
above, there is no substantial new information indicating that there would be a new significant impact
related to recreation requiring major revisions to the 2008 DMP Update EIR.
The 2008 DMP Update EIR did not identify any significant impacts to recreation, and no new
information, mitigation, or alternatives to the project have been identified that would substantially
reduce one or more significant impacts pertaining to recreation.
With regards to potential recreation impacts, the New and Revised Project Components are within the
scope of the 2008 DMP Update EIR. None of the conditions under Section 15162 requiring a subsequent
EIR have been met.
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January 2026 3-39 Addendum
3.10 GEOLOGY/SOILS
3.10.1 Previous Analysis
The analysis of the impacts to geology/soils for the 2008 DMP Update is contained in the 2008 DMP
Update EIR, Section 4.8, pages 4.8-1 to 4.8-9. Cumulative impacts related to geology/soils are discussed
in Section 5.2.1.8 on page 5-14 of the 2008 DMP Update EIR. With respect to the programmatic
evaluation of the impacts of the PLDA Project Components, the EIR made the following conclusions:
1) Assuming a site-specific geotechnical analysis would be conducted for 2008 DMP Update
components and site-specific remediation measures would be incorporated into facility project
design, no impacts due to soils or seismic activity are anticipated to occur. Operation and
maintenance activities would occur in existing or proposed drainage facilities and would not
involve the construction of new structures. Potential impacts would be less than significant and
no mitigation is required.
2) All construction, operation, and maintenance would be performed in accordance with the
requirements of the City’s Grading Ordinance (Municipal Code Title 15), which requires the
control of erosion during construction and the stabilization of all disturbed surfaces upon
completion of construction (City of Carlsbad 1994). Potential impacts would be less than
significant and no mitigation is required.
3.10.2 Analysis of the Project Changes
3.10.2.1 Direct and Indirect Impacts
All of the new project components fall within the description of the types of projects identified in
Section 3.3.2 of the 2008 DMP Update EIR, and the nature of work is consistent with the project design
features/methods and construction activities described in Section 3.3.5 of the 2008 DMP Update EIR.
Furthermore, no changes are proposed to the revised project components that would result in project
components that are inconsistent with the descriptions in Sections 3.3.2 and 3.3.5 of the 2008 DMP
Update EIR. As described in the 2008 DMP Update EIR, no PLDA project components are proposed
within an area where mineral resources are known to be present. Similarly, based on a review of the
General Plan Open Space, Conservation, and Recreation Element, none of the New or Revised Project
Components are located within areas managed for production of resources (including major mineral
resources, forestry, and agriculture, among others).
As with the 2008 DMP Update evaluated in the 2008 DMP Update EIR, specific soil types and rock
formations that would be affected by the New or Revised Project Component are unknown at this time.
In accordance with the project design features/methods and construction measures described in
Table 3-6 of the DMP EIR (included in Appendix C of this Addendum), site-specific geotechnical
evaluations will be conducted for project components involving excavation, grading, or construction of
new structures, and appropriate remediation would be incorporated into the project component design
to minimize impacts associated with soils. A review of available geologic hazards data from the
California Department of Conservation (DOC) supports the 2008 DMP Update EIR statement that there
are no known faults or Alquist-Priolo fault zone areas within the City (DOC 2021). Compliance with the
project design features/methods and construction measures in Table 3-6 includes performing
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Addendum 3-40 January 2026
construction in accordance with the City’s Grading Ordinance (Municipal Code Title 15), the City Building
Code (Municipal Code Title 18), and the Uniform Building Code, as applicable, which would minimize
impacts related to seismic hazards. No changes are required to the impact conclusions in the 2008 DMP
Update EIR presented in Section 3.10.1 of this Addendum; impacts would be less than significant.
3.10.2.2 Cumulative Impacts
As discussed in the 2008 DMP Update EIR, geologic conditions in the region would essentially remain the
same regardless of implementation of the 2008 DMP Update EIR and the New or Revised Project
Components; therefore, the cumulative contribution to impacts related to geology and soils would be
less than significant.
3.10.3 Substantial Changes with Respect to Circumstances or New Information of Substantial
Importance
No changes have been identified with respect to the circumstances under which the Project Changes
would be undertaken, and there is no new information of substantial importance that has become
available relative to geology/soils.
3.10.4 Conclusion
Based on the foregoing analysis and information, there is no evidence that the New or Revised Project
Components require a major change to the 2008 DMP Update EIR. The Project Changes would not result
in new significant environmental impacts related to geology/soils, and there would not be a substantial
increase in the severity of impacts described in the 2008 DMP Update EIR. Implementation of the
project design features/methods and construction measures identified in Table 3-6 of the 2008 DMP
Update EIR (included in Appendix C of this Addendum) would ensure that temporary and permanent
impacts would remain less than significant and no mitigation is required.
No major changes to the project area or the general scope and magnitude of the project components
have taken place since preparation of the 2008 DMP Update EIR that would require revisions to the
analysis in the EIR. There is no information in the record or otherwise available that indicates that there
are substantial changes in circumstances pertaining to geology/soils that would require major changes
to the 2008 DMP Update EIR.
This Addendum has analyzed all available relevant information to determine whether there is new
information that was not available at the time the 2008 DMP Update EIR was certified, indicating that a
new significant effect not reported in that document may occur. Based on the information and analyses
above, there is no substantial new information indicating that there would be a new significant impact
related to geology/soils requiring major revisions to the 2008 DMP Update EIR.
The 2008 DMP Update EIR did not identify any significant impacts related to geology/soils, and no new
information, mitigation, or alternatives to the project have been identified that would substantially
reduce one or more significant impacts pertaining to geology/soils.
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January 2026 3-41 Addendum
With regards to potential geology/soils impacts, the New and Revised Project Components are within
the scope of the 2008 DMP Update EIR. None of the conditions under Section 15162 requiring a
subsequent EIR have been met.
3.11 HYDROLOGY/WATER QUALITY
3.11.1 Previous Analysis
The analysis of the impacts to hydrology/water quality for the 2008 DMP Update is contained in the
2008 DMP Update EIR, Section 4.9, pages 4.9-1 to 4.9-20. Cumulative impacts related to hydrology/
water quality are discussed in Section 5.2.1.9 on page 5-14 of the 2008 DMP Update EIR. With respect to
the programmatic evaluation of the impacts of the PLDA Project Components, the EIR made the
following conclusion:
1) Construction and maintenance of proposed infrastructure components could result in
temporary impacts to water quality. The requirement for preparation of appropriate storm
water management documents has been included in the design features for the project.
Implementation of the proposed 2008 DMP Update would serve to indirectly improve storm
water quality within the city. Overall, the proposed drainage improvements would reduce
flooding potential, decrease erosion and sedimentation, and enhance storm water flows within
the city. In addition, all proposed drainage facilities and infrastructure would comply with the
City’s Standard Design Criteria to ensure they are properly sized to handle 100-year flood
conditions. Potential impacts would be less than significant and no mitigation is required.
3.11.2 Analysis of the Project Changes
Section 4.9.1.3 (pates 4.9-2 to 4.9-5) of the 2008 DMP Update EIR provides an overview of the
regulatory authority related to hydrology and water quality. Since the certification of the 2008 DMP
Update EIR, several regulatory permits have been renewed or reissued. The National Pollutant Discharge
Elimination System (NPDES) San Diego Municipal Storm Water Permit is now Water Quality Order No.
2013-0001, as amended by Order Nos. R9-2015-001 and R9-2015-0100. The permit covering
construction projects disturbing at least 1 acre of land, the Construction General Permit, is now Order
WQ 2022-0057-DWQ NPDES No. CAS000002. Periodic permit updates are required as part of applicable
regulations, and ensure that activities subject to these requirements are conducted in accordance with
current regulatory requirements. As with the 2008 DMP Update project components, the New or
Revised Project Components will comply with the applicable permit requirements in effect at the time of
project-specific permitting and construction.
Table 4.9-1 (pages 4.9-9 to 4.9-11) in the 2008 DMP Update EIR summarizes the PLDA project
components that would be located within floodplains or drainage channels as identified on the Federal
Emergency Management Agency (FEMA) Flood Insurance Rate Maps. Table K provides comparable
information for the New or Revised Project Components.
3.11.2.1 Direct and Indirect Impacts
As shown in Table K, consistent with the project components discussed in the 2008 DMP Update EIR,
some are located within the 100-year or 500-year floodplain or within drainage channels. All of the new
project components fall within the description of the types of projects identified in Section 3.3.2 of the
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2008 DMP Update EIR, and the nature of work is consistent with the project design features/methods
and construction activities described in Section 3.3.5 of the 2008 DMP Update EIR. Furthermore, no
changes are proposed to the revised project components that would result in project components that
are inconsistent with the descriptions in Sections 3.3.2 and 3.3.5 of the 2008 DMP Update EIR. Impacts
would be short term, associated with construction of project components, and would be minimized
through implementation of the project design features/methods and construction measures identified
in Table 3-6 of the 2008 DMP Update EIR (included in Appendix C of this Addendum). Long-term impacts
would be beneficial to hydrology, drainage capacity, and water quality. No changes are required to the
impact conclusions in the 2008 DMP Update EIR presented in Section 3.11.1 of this Addendum; impacts
would be less than significant.
Table K: Impacts Related to Floodplains and Drainage Channels
Project
Component ID1 Project Name 100-year Floodplain
500-year
Floodplain
Drainage
Channel
Basin A – Buena Vista Creek Watershed
BVC-1 Jefferson Street North No No No
BVC-2* Jefferson Street South No No No
BVC-3* Marron and Monroe
Drainage Improvements No No No
BVC-4* Marron and Jefferson Multi-
Benefit Basin Yes No No
BVC-5* Laguna Drive Storm Drain
Upsize
Yes; edge of project area only;
proposed structures are outside
floodplain limits
No No
Basin B – Agua Hedionda Creek Watershed
BJ-1 Rancho Carlsbad Multi-
Benefit Basin Yes No Yes
AHC-2 College Boulevard Storm
Drain Extension Yes No Yes
AHC-3 Cantarini and Holly Springs
Culvert Yes No Yes
AHC-4* Park Drive and Hillside Drive
Storm Drain Upsize No No No
Basin C – Encinas Creek Watershed
EC-1 Paseo Del Norte Box Culvert No No No
Basin D – San Marcos Creek Watershed
SMC-1 Batiquitos Lagoon
Stormwater Treatment
System
No No No
Sources: National Flood insurance Program Flood Insurance Rate Map. Panels 0761, 0762, 0764, 0768, 0769, and 1032 (FEMA 2021).
1 Project Components marked with * are New Project Components.
FEMA = Federal Emergency Management Agency
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January 2026 3-43 Addendum
3.11.2.2 Cumulative Impacts
As described for the 2008 DMP Update in the 2008 DMP Update EIR, water quality control measures and
project-specific Best Management Practices (BMPs) required in project-specific Storm Water Pollution
Prevention Plans (SWPPPs) would minimize impacts to water quality. Furthermore, implementation of
the New or Revised Project Components would improve overall drainage and indirectly improve long-
term water quality, and would not substantially increase the amount of impervious surfaces. Therefore,
the cumulative effects of the New or Revised Project Components would be beneficial to water quality,
storm water conveyance, and flood control, and the project would not significantly contribute to a
cumulative hydrology or water quality impact.
3.11.3 Substantial Changes with Respect to Circumstances or New Information of Substantial
Importance
No changes have been identified with respect to the circumstances under which the Project Changes
would be undertaken, and there is no new information of substantial importance that has become
available relative to hydrology/water quality.
3.11.4 Conclusion
Based on the foregoing analysis and information, there is no evidence that the New or Revised Project
Components require a major change to the 2008 DMP Update EIR. The Project Changes would not result
in new significant environmental impacts related to hydrology/water quality, and there would not be a
substantial increase in the severity of impacts described in the 2008 DMP Update EIR. Implementation
of the project design features/methods and construction measures identified in Table 3-6 of the 2008
DMP Update EIR (included in Appendix C of this Addendum) would ensure that temporary and
permanent impacts would remain less than significant and no mitigation is required.
No major changes to the project area or the general scope and magnitude of the project components
have taken place since preparation of the 2008 DMP Update EIR that would require revisions to the
analysis in the EIR. There is no information in the record or otherwise available that indicates that there
are substantial changes in circumstances pertaining to hydrology/water quality that would require major
changes to the 2008 DMP Update EIR.
This Addendum has analyzed all available relevant information to determine whether there is new
information that was not available at the time the 2008 DMP Update EIR was certified, indicating that a
new significant effect not reported in that document may occur. Based on the information and analyses
above, there is no substantial new information indicating that there would be a new significant impact
related to hydrology/water quality requiring major revisions to the 2008 DMP Update EIR.
The 2008 DMP Update EIR did not identify any significant impacts related to hydrology/water quality,
and no new information, mitigation, or alternatives to the project have been identified that would
substantially reduce one or more significant impacts pertaining to hydrology/water quality.
With regards to potential hydrology/water quality impacts, the New and Revised Project Components
are within the scope of the 2008 DMP Update EIR. None of the conditions under Section 15162 requiring
a subsequent EIR have been met.
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3.12 BIOLOGICAL RESOURCES
3.12.1 Previous Analysis
The analysis of the impacts to biological resources for the 2008 DMP Update is contained in the 2008
DMP Update EIR, Section 4.10, pages 4.10-1 to 4.10-77. Cumulative impacts related to biological
resources are discussed in Section 5.2.1.10 on page 5-15 of the 2008 DMP Update EIR. With respect to
the programmatic evaluation of the impacts of the PLDA Project Components, the EIR made the
following conclusions (Mitigation Measures referenced have been included in Appendix C of this
Addendum):
1) Impact Bio-1: Per the City’s HMP, implementation of proposed 2008 DMP Update components
could result in a long-term potentially significant impact if sensitive habitats are permanently
destroyed or degraded. This would also result in a potentially significant cumulative impact to
biological resources.
Implementation of the Mitigation Measures Bio 1-a through Bio 1-d would be required for DMP
components that would impact sensitive HMP habitats and would reduce direct and cumulative
impacts to below a level of significance. Note that the descriptions of Type A through F habitats
are per Table 11 of the HMP. Avoidance and on-site mitigation are the priority. Future project
level environmental review for 2008 DMP Update components that would impact biological
resources would be provided to the Wildlife Agencies for review to verify consistency with the
City’s HMP.
Implementation of Mitigation Measures Bio-1e through Bio-1g shall be required for DMP
components that would result in indirect impacts to coastal California gnatcatcher, within 150
meters (500 feet) of the proposed project footprint, from construction-generated noise and
would reduce impacts to below a level of significance.
Implementation of Mitigation Measures Bio-1h through Bio-1j shall be required for DMP
components that result in indirect impacts to the least Bell’s vireo, within 150 meters (500 feet)
of the proposed project footprint, from construction-generated noise and would reduce impacts
to below a level of significance.
Implementation of Mitigation Measures Bio-1k through Bio-1o shall be required for DMP
components that would result in indirect impacts to the southwestern willow flycatcher, within
150 meters (500 feet) of the proposed project footprint, from construction-generated noise and
would reduce impacts to below a level of significance.
With implementation of Mitigation Measures Bio-1a through Bio-1m, impacts related to Impact
Bio-1 would be less than significant.
2) Impact Bio-2: Long-term or permanent potentially significant impacts could result from loss of
riparian and wetland habitats. This would contribute to the regional loss of riparian and wetland
habitat, resulting in a significant cumulative impact.
With implementation of Mitigation Measures Bio-2a and Bio-2b, impacts related to Impact Bio-
2 would be less than significant.
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January 2026 3-45 Addendum
3) Impact Bio-3: Per the City’s HMP, the loss of State and/or federally listed plant species is
considered a potentially significant impact. The loss of sensitive plant species at a regional level
would contribute to a significant cumulative impact.
With implementation of Mitigation Measure Bio-3, impacts related to Impact Bio-3 would be
less than significant.
4) Impact Bio-4: Drainage facility improvements that result in substantial vegetation clearing or
impede wildlife movement within core areas and linkages would result in a potentially
significant impact.
With implementation of Mitigation Measure Bio-4, impacts related to Impact Bio-4 would be
less than significant.
3.12.2 Analysis of the Project Changes
Section 4.10.1.1 (pages 4.10-1 through 4.10-25) of the 2008 DMP Update EIR presents a general
summary of the existing conditions related to biological resources. While some changes have occurred
to the distribution of vegetation types throughout the region as a result of development and mitigation,
the vegetation communities described in this section remain accurate. Table 4.10-2 (pages 4.10-18 to
4.10-20) and Table 4.10-3 (pages 4.10-20 to 4.10-22) of the 2008 DMP Update EIR identify the sensitive
plant and wildlife species found in Carlsbad based available data. A review of the California Natural
Diversity Database and the California Native Plant Society Inventory for the New or Revised Project
Components determined that subsequent to certification of the 2008 DMP Update EIR, one additional
sensitive plant species, Coulter’s goldfields, which was not noted in the 2008 DMP Update EIR, has since
been recorded within the Basin D area, and one sensitive animal species, western snowy plover, has
since been recorded in more basins than was noted in the 2008 DMP Update EIR. Table L provides the
updated information for these species consistent with Table 4.10-2, and Table M provides the
information consistent with Table 4.10-3, of the 2008 DMP Update EIR. Note that the California
Department of Fish and Wildlife (CDFW) was formerly called the California Department of Fish and
Game and is referred to as such in the 2008 DMP Update EIR.
As discussed in Section 4.10.3.1 (pages 4.10-55 to 4.10-60) in the 2008 DMP Update EIR, the project
components each have the potential to directly and indirectly impact sensitive species and habitats
through vegetation removal, alteration of drainages, project-related noise and dust, and conflicts with
adopted plans and policies. Table 4.10-8 in the 2008 DMP Update EIR provides an overview of impacts
to vegetation types from PLDA project components. Table N provides similar information for the New or
Revised Project Components based on a desktop review of aerial photographs and available data.
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Table L: Additional Sensitive Plant and Wildlife Species Found in Carlsbad, by Basin
Common Name Scientific Name Status Designation A B C D
Plant
Coulter’s goldfields Lathenia glabrata ssp. coulteri CNPS List 1B 9
Wildlife
Western snowy plover Charadrius alexandrinus nivosus
USFWS: FT
CDFW: SSC
HMP: covered
9 9 9 9
These species are in addition to those listed in Table 4.10-2 of the 2008 DMP Update EIR.
USFWS = U.S. Fish and Wildlife Service
FT: Federally listed threatened.
CDFW = California Department of Fish and Wildlife
SSC: Species of Special Concern: Species that because of declining population levels, limited ranges, and/or continuing threats
have been made vulnerable to extinction.
CNPS = California Native Plant Society
1B: plants rare, threatened, or endangered in California or elsewhere.
HMP = Carlsbad Habitat Management Plan
Covered: species that will be covered under the take authorization for the HMP.
Table M: Additional Sensitive Plant Species, by General Habitat Type
Species Habitat Type
Common Name Scientific Name
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/
Es
t
u
a
r
y
Plant
Coulter’s goldfields Lathenia glabrata ssp. coulteri 9 9 9 9 9
This species is in addition to those listed in Table 4.10-3 of the 2008 DMP Update EIR.
Table N: Impacts to Vegetation Types from PLDA Project Components
Project
Component ID1
Name Vegetation Type Impacted2
Basin A – Buena Vista Creek Watershed
BVC-1 Jefferson Street North Disturbed/Developed
BVC-2* Jefferson Street South Disturbed/Developed
BVC-3* Marron and Monroe Drainage
Improvements
Disturbed/Developed, Eucalyptus Woodland, Nonnative
Grassland
BVC-4* Marron and Jefferson Multi-Benefit
Basin
Disturbed/Developed, Coastal Sage Scrub, Wetland (Marsh),
Eucalyptus Woodland
BVC-5* Laguna Drive Storm Drain Upsize Disturbed/Developed
Basin B – Agua Hedionda Creek Watershed
BJ-1 Rancho Carlsbad Multi-Benefit Basin Nonnative Grassland, Disturbed/Developed, and Eucalyptus
Woodland
AHC-2 College Boulevard Storm Drain
Extension
Disturbed/Developed, Nonnative Grassland, Coastal Sage
Scrub, Riparian
AHC-3 Cantarini and Holly Springs Culvert Disturbed/Developed, Nonnative Grassland, Coastal Sage
Scrub, Riparian
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Table N: Impacts to Vegetation Types from PLDA Project Components
Project
Component ID1
Name Vegetation Type Impacted2
AHC-4* Park Drive and Hillside Drive Storm
Drain Upsize
Disturbed/Developed, Eucalyptus Woodland
Basin C – Encinas Creek Watershed
EC-1 Paseo Del Norte Box Culvert Coastal Sage Scrub, Riparian
Basin D – San Marcos Creek Watershed
SMC-1 Batiquitos Lagoon Stormwater
Treatment System
Disturbed/Developed, Nonnative Grassland
Based on Table 4.10-8 in the 2008 DMP Update EIR.
1 Project Components marked with * are New Project Components.
2 Vegetation types listed include the areas surrounding the project that could be subject to indirect impacts. Disturbed/Developed
includes some ornamental landscaped areas.
3.12.2.1 Direct and Indirect Impacts
All of the new project components fall within the description of the types of projects identified in
Section 3.3.2 of the 2008 DMP Update EIR, and the nature of work is consistent with the project design
features/methods and construction activities described in Section 3.3.5 of the 2008 DMP Update EIR.
Furthermore, no changes are proposed to the revised project components that would result in project
components that are inconsistent with the descriptions in Sections 3.3.2 and 3.3.5 of the 2008 DMP
Update EIR. The locations and updated data related to species distribution were reviewed for the New
or Revised Project Components. Based on this review, potential impacts were previously characterized
in the 2008 DMP Update EIR, and no new impacts would occur. Implementation of the project design
features/methods and construction measures identified in Table 3-6 of the 2008 DMP Update EIR
(included in Appendix C of this Addendum) and Mitigation Measures Bio-1a through Bio 1o, Bio-2,
Bio-2b, Bio-3, and Bio-4 would ensure that temporary and permanent impacts would remain less than
significant. No changes to the impact conclusions in the 2008 DMP Update EIR presented in Section
3.12.1 of this Addendum are necessary; impacts would be less than significant with mitigation
incorporated.
3.12.2.2 Cumulative Impacts
The 2008 DMP Update EIR identified potentially cumulative impacts to biological resources as a result of
potentially significant long-term impacts to biological resources of DMP project components when
considered together with other development projects in Carlsbad and the region. However, mitigation
measures have been incorporated so that the project components would be consistent with the
Carlsbad HMP, which takes a regional and cumulative approach to establishing mitigation requirements.
Therefore, although impacts from project components could contribute to significant biological impacts
in the region, implementation of Mitigation Measures Bio-1 through Bio-44 would reduce impacts to a
less than significant level, directly and in the cumulative context. The impacts that would result from
New or Revised Project Components are consistent with those evaluated in the 2008 DMP Update EIR,
and the project components would be subject to Mitigation Measures Bio-1 through Bio-4, which
addressed programmatic impacts from PLDA project components. The Carlsbad HMP remains a valid
4 The 2008 DMP Update EIR included additional Mitigation Measures Bio-5 through Bio-8, which specifically applied to the
project-level analysis of project components at a more advanced level of design. These measures are location-specific and
are not broadly applicable to the programmatic analysis of PLDA project components.
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Addendum 3-48 January 2026
plan with regulatory agency approval, and compliance with its requirements through implementation of
the Mitigation Measures Bio-1 through Bio-4 will ensure that cumulative impacts of the New or Revised
Project Components to biological resources will be less than significant.
3.12.3 Substantial Changes with Respect to Circumstances or New Information of Substantial
Importance
As discussed in Section 3.3 of this Addendum, the City’s Local Coastal Program was updated in 2019, and
project components within the Coastal Zone are identified in Table C of this Addendum. Project
components within the Coastal Zone would require project-level review at the time they are proposed
to be implemented for consistency with the California Coastal Act and specific Local Coastal Program
policies and provisions prior to the issuance of a Coastal Development Permit; therefore, New or
Revised Project Components would be subject to the requirements of the version of the Local Coastal
Program in effect at the time of project approval. Therefore, the update to the Local Coastal Program
does not constitute a substantial change with respect to the circumstances under which the project is
being undertaken and does not present new information of substantial importance.
As discussed in Section 3.12.2, additional sensitive species detections have occurred within the project
area since the certification of the 2008 DMP Update EIR. The programmatic analysis did not include site-
specific surveys or rely on detailed species distribution information to determine impacts and
mitigation, but rather incorporated project measures and mitigation to ensure that impacts from project
components to sensitive biological resources would be reduced to a level below significance. The
efficacy of these measures is not affected by the additional detection of sensitive species. Therefore,
this information does not constitute a substantial change with respect to the circumstances under which
the project is being undertaken and does not present new information of substantial importance.
As referenced in Section 3.3.3.2, project component BJ-1 would be constructed within an 11.6-acre
parcel, which is now designated as open space and high density residential development. The City’s
adopted General Plan Housing Element identifies the site as providing 155 units of lower income
housing, requiring a minimum of 5.8 acres. The parcel is also within an HMP Standards Area. The project
component would have a footprint of approximately 2.2 acres (located within the southern 3.4 acres of
the parcel); therefore, it is expected there would be sufficient acreage remaining on site to both
accommodate the required number of units and to comply with the HMP Standards.
No other changes have been identified with respect to the circumstances under which the Project
Changes would be undertaken, and there is no new information of substantial importance that has
become available relative to biological resources.
3.12.4 Conclusion
Based on the foregoing analysis and information, there is no evidence that the New or Revised Project
Components require a major change to the 2008 DMP Update EIR. The Project Changes would not result
in new significant environmental impacts related to biological resources, and there would not be a
substantial increase in the severity of impacts described in the 2008 DMP Update EIR. Implementation
of the project design features/methods and construction measures identified in Table 3-6 of the 2008
DMP Update EIR (included in Appendix C of this Addendum) and Mitigation Measures Bio-1a through
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Bio 1o, Bio-2, Bio-2b, Bio-3, and Bio-4 remain applicable and would ensure that temporary and
permanent impacts would remain less than significant.
No major changes to the project area or the general scope and magnitude of the project components
have taken place since preparation of the 2008 DMP Update EIR that would require revisions to the
analysis in the EIR. There is no information in the record or otherwise available that indicates that there
are substantial changes in circumstances pertaining to biological resources that would require major
changes to the 2008 DMP Update EIR.
This Addendum has analyzed all available relevant information to determine whether there is new
information that was not available at the time the 2008 DMP Update EIR was certified, indicating that a
new significant effect not reported in that document may occur. Based on the information and analyses
above, there is no substantial new information indicating that there would be a new significant impact
related to biological resources requiring major revisions to the 2008 DMP Update EIR.
There is no new information, mitigation, or alternatives to the project that would substantially reduce
one or more significant impacts pertaining to biological resources identified and considered in the 2008
DMP Update EIR.
With regards to potential biological resource impacts, the New and Revised Project Components are
within the scope of the 2008 DMP Update EIR. None of the conditions under Section 15162 requiring a
subsequent EIR have been met.
3.13 CULTURAL RESOURCES
3.13.1 Previous Analysis
The analysis of the impacts to cultural resources for the 2008 DMP Update is contained in the 2008 DMP
Update EIR, Section 4.11, pages 4.11-1 to 4.11-16. Cumulative impacts related to cultural resources are
discussed in Section 5.2.1.11 on page 5-15 of the 2008 DMP Update EIR. With respect to the
programmatic evaluation of the impacts of the PLDA Project Components, the EIR made the following
conclusion (mitigation measures referenced have been included in Appendix C of this Addendum):
1) Impact Cult-1: For areas not adequately surveyed for cultural resources, access roads (for
construction or operation and maintenance) traversing previously undisturbed areas or projects
requiring surface disturbance in undeveloped areas could lead to potentially significant impacts
to surface cultural deposits.
With implementation of Mitigation Measure Cult-1, this impact would be less than significant.
2) Impact Cult-2: Ground-disturbing project activities or excavation into intact native soils could
result in potentially significant impacts to cultural resources that have not yet been discovered.
With implementation of Mitigation Measure Cult-2, this impact would be less than significant.
3.13.2 Analysis of the Project Changes
Section 4.11.1.1 (pages 4.11-2 to 4.11-3) of the 2008 DMP Update EIR describes the archival research
that was conducted in support of the programmatic analysis. Updated archival research was conducted
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for areas near New or Revised Project Components in support of this Addendum. Archival research
consisted of an archaeological and historical record and literature review conducted at the South
Coastal Information Center (SCIC) at San Diego State University and at the San Diego Museum of Man.
The data reviewed included recorded resources, prior cultural resource studies, historic maps, and
National Register of Historic Places (NRHP) and California Register of Historical Resources (CRHR)
information for the project area. This record search is on file at the LSA Carlsbad office. Consistent with
the approach used in the 2008 DMP Update EIR, the record and literature search included each
individual new project component and a quarter-mile radius around each component. Information from
this record search was used to determine if cultural resource surveys had been conducted for each
component and whether any cultural resources had been recorded within proposed project limits. This
information identified those areas that have already been surveyed and the type of resources that might
be found if an area has not yet been surveyed.
The updated record search was conducted on September 3, 2021. It showed that 120 cultural resources
studies had been conducted within the quarter-mile search radius. Of these, 37 previous studies were
within or adjacent to the New or Revised Project Components and 83 were not. The 37 previous studies
within or adjacent to the New or Revised Project Components consisted of survey (19), excavation (4),
survey and excavation (2), evaluation/assessment/inventory (4), EIR (4), monitoring (2), records
search (1), and historic resource studies (1).
For some of the New or Revised Project Components, cultural resource surveys have been conducted
that cover some or all of the project areas associated with each component. Specifically, the research
indicates that nearly all of the project areas associated with Project Components BJ-1, ACH-3, and ACH-2
have been surveyed previously. Portions of the project areas associated with Project Components
BVC-3, BVC-4, ACH-4, and SMC-1 have been surveyed. No previous surveys have been recorded near
Project Components BVC-1, BVC-2, BVC-5, or EC-1.
Cultural resource sites have been recorded in or adjacent to Project Components BVC-4 (P-37-30500);
BVC-5 (P-37-627 and P-37-38297); BJ-1 (P-37-17303); ACH-2 (P-37-9092); ACH-3 (P-37-9092 and
P-37-18284); and ACH-4 (P-37-19009). Site P-37-9092 extends onto both Project Component IDs ACH-2
and ACH-3. Determinations of significance and eligibility for listing in the CRHR/or NRHP are typically
based on site testing, including intensive survey and excavation. One site, P-37-18284 (located near
Project Component ACH-3), is unlikely to be found eligible because it consists only of three items. Sites
P-37-9092 and P-37-17303 were tested in the past and recommended as not significant and therefore
not eligible for listing. However, only a portion of P-37-9092 was tested and the tested area is not
specified on site forms.
Table 4.11-1 (page 4.11-3) of the 2008 DMP Update EIR summarizes the results of archival research for
the 2008 DMP Update. Table O presents comparable information as an update to Table 4.11-1 of the
2008 DMP Update EIR.
3.13.2.1 Direct and Indirect Impacts
As stated in Section 4.11.3.1 (pages 4.11-6 to 4.11-10) of the 2008 DMP Update EIR, ground-disturbing
activities associated with project components that occur within intact native soils have the potential to
impact identified or unknown cultural resources. Table O identifies known cultural resources that have
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been recorded within or adjacent to New or Revised Project Components. Due to the uncertainty of site
locations and boundaries and the potential for previously undiscovered resources to be present below
the surface, it is anticipated that, as with the 2008 DMP Update, any of the New or Revised Project
Components within currently undeveloped areas could result in potential significant impacts to surface
cultural resources. Similarly, any components that would result in subsurface excavation of native soils
could result in potential significant impacts to subsurface cultural resources. Table 4.11-2 (page 4.11-7)
in the 2008 DMP Update EIR outlines the 2008 DMP Update project components that would be located
in previously unsurveyed undeveloped areas (potential surface impacts) or that entail the potential
excavation of native soils. Table P provides comparable information for the New or Revised Project
Components.
As with the 2008 DMP Update, any New or Revised Project Components located in undeveloped areas
or that would entail excavation into native soils have the potential to result in a significant impact to
cultural resources. All of the new project components fall within the description of the types of projects
identified in Section 3.3.2 of the 2008 DMP Update EIR, and the nature of work is consistent with the
project design features/methods and construction activities described in Section 3.3.5 of the 2008 DMP
Update EIR. Furthermore, no changes are proposed to the revised project components that would result
in project components that are inconsistent with the descriptions in Sections 3.3.2 and 3.3.5 of the 2008
DMP Update EIR. In the case of the New or Revised Project Components, Mitigation Measure Cult-1
would reduce potential impacts to surface resources to a level below significance, and Mitigation
Measure Cult-2 would reduce potential impacts to subsurface resources to a level below significance
(note that the mitigation measures are consistent with guidelines that have been subsequently adopted
by the City; refer to Section 3.13.3 for additional information). No changes to the impact conclusions in
the 2008 DMP Update EIR presented in Section 3.13.1 of this Addendum are necessary; impacts would
be less than significant with mitigation incorporated.
Table O: New or Revised Project Components Within or Adjacent to Cultural Resources Areas
Project
Component
ID1
Resource Number(s)
Resource
Description
Date(s)
Recorded
CRHR and NRHP
Eligibility
Primary
Number
(P-37-)
Trinomial
(CA-SDI-)
Museum
of Man
(SDM-W-)
Basin A – Buena Vista Creek Watershed
BVC-4 30500 19,375 — Low-density shell
scatter
2009
(2014) Unlikely
BVC-5* 627 627 142 Scattered habitation
debris 1958 Unknown
BVC-5* 38297 22,605 —
Low-density shell,
with historic glass
and faunal bone
2018 Unlikely
Basin B – Agua Hedionda Creek Watershed
BJ-1 17303 15,069 — Small habitation
with bedrock milling
1999
(2001,
2015)
Testing
recommendation: not
significant
ACH-2 9092 9,092 —
Large habitation site
(only west end in
project area)
1981
(2001,
2016)
Portions tested and
recommended: not
significant
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Table O: New or Revised Project Components Within or Adjacent to Cultural Resources Areas
Project
Component
ID1
Resource Number(s)
Resource
Description
Date(s)
Recorded
CRHR and NRHP
Eligibility
Primary
Number
(P-37-)
Trinomial
(CA-SDI-)
Museum
of Man
(SDM-W-)
ACH-3 9092 9,092 — Large habitation site
1981
(2001,
2016)
Portions tested and
recommended: not
significant
ACH-3 18284 — — 1 flake tool, 1 flake,
1 pc. shell
1998
(2016)
Testing
recommendation: not
significant
ACH-4* 19009 13,701 130 Large habitation site
1950s
(1994,
2006)
Potentially eligible
This table is an update to Table 4.11-1 in the 2008 DMP Update EIR.
Note: New or Revised Project Components not in proximity to Cultural Resources Areas are not included in the table.
1 Project Components marked with * are New Project Components.
Table P: Cultural Resources Survey and Monitoring Requirements for New or Revised Project
Components
Project
Component ID1 Name
Potential Impact to Surficial
Cultural Resources?2
Potential Impact to Subsurface
Cultural Resources?3
Basin A – Buena Vista Creek Watershed
BVC-1 Jefferson Street North No Yes
BVC-2* Jefferson Street South No Yes
BVC-3* Marron and Monroe Drainage
Improvements Yes Yes
BVC-4 Marron and Jefferson Multi-
Benefit Basin Yes Yes
BVC-5* Laguna Drive Storm Drain
Upsize Yes Yes
Basin B - Agua Hedionda Creek Watershed
BJ-1 Rancho Carlsbad Multi-Benefit
Basin Yes Yes
ACH-2 College Boulevard Storm Drain
Extension Yes Yes
ACH-3 Cantarini and Holly Springs
Culvert Yes Yes
ACH-4* Park Drive and Hillside Drive
Storm Drain Upsize Yes Yes
Basin C – Encinas Creek Watershed
EC-1 Paseo Del Norte Box Culvert Yes Yes
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Table P: Cultural Resources Survey and Monitoring Requirements for New or Revised Project
Components
Project
Component ID1 Name
Potential Impact to Surficial
Cultural Resources?2
Potential Impact to Subsurface
Cultural Resources?3
Basin D – San Marcos Creek Watershed
SMC-1 Batiquitos Lagoon Stormwater
Treatment System No Yes
This table is an update to Table 4.11-1 in the 2008 DMP Update EIR.
1 Project Components marked with * are New Project Components.
2 Project components would potentially affect resources at the surface if any portion of the project component is located in undeveloped
areas where prior surveys have not been conducted or provide insufficient information.
3 Proposed project components would potentially impact subsurface cultural resources if the project component would involve grading or
excavation of undisturbed native soils.
3.13.2.2 Cumulative Impacts
The 2008 DMP Update EIR found that although project components, along with other development
projects, could have potentially significant impacts to cultural or archaeological resources, these types of
impacts are localized and can be addressed through the implementation of feasible mitigation
measures. Impacts to cultural resources from DMP project components would be reduced through
implementation of the project design features/methods and construction measures in Table 3-6 of the
2008 DMP Update EIR and Mitigation Measures Cult-1 and Cult-2. These measures would reduce
impacts to a level below significance, and there would not be a considerable contribution to a significant
cumulative cultural resource impact. The New or Revised Project Components would have comparable
impacts to cultural resources as those in the 2008 DMP Update, and there would be no change in the
cumulative impact determination. The DMP with the Project Changes would not result in a considerable
contribution to a significant cumulative impact to cultural resources.
3.13.3 Substantial Changes with Respect to Circumstances or New Information of Substantial
Importance
As described above, the updated archival research conducted in support of the New or Revised Project
Components did not identify any substantial changes with respect to the circumstances under which the
project would be undertaken or any new information of substantial importance.
Since the certification of the 2008 DMP Update EIR, the City has adopted the Carlsbad Tribal, Cultural,
and Paleontological Resources Guidelines (City of Carlsbad 2017). Among other things, these guidelines
present the roles and responsibilities of agencies, tribes, consultants, and applicants, and set forth
procedures for analysis, identifying resources, and coordinating consultation. New or Revised Project
Components would be subject to the requirements set forth in these guidelines at the time project-level
review is conducted. Mitigation Measures Cult-1 and Cult-2 identified in the 2008 DMP Update EIR are
consistent with the guidelines that have since been adopted by the City. Specifically, Cult-1 sets forth
the circumstances under which the measure would apply, pre-construction requirements for an
archaeological field survey, actions to be taken in the event of positive or negative findings, reporting,
and consultation with local Native American groups. Cult-2 sets forth requirements for construction
monitoring (archaeological and Native American monitors), confirmation of pre-construction research
and surveys, actions to be taken in the event of a discovery, actions to be taken in the event human
I I I
I I I
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remains are discovered, and reporting requirements at the conclusion of monitoring. The requirements
for all of these actions are addressed in the City’s adopted guidelines. As plans for each project
component are submitted for discretionary approval, the City may opt to incorporate language from the
adopted guidelines, which would cover all actions identified in Mitigation Measures Cult-1 and Cult-2.
No other changes have been identified with respect to the circumstances under which the Project
Changes would be undertaken, and there is no new information of substantial importance that has
become available relative to cultural resources.
3.13.4 Conclusion
Based on the foregoing analysis and information, there is no evidence that the New or Revised Project
Components require a major change to the 2008 DMP Update EIR. The Project Changes would not result
in new significant environmental impacts related to cultural resources, and there would not be a
substantial increase in the severity of impacts described in the 2008 DMP Update EIR. Implementation
of Mitigation Measures Cult-1 and Cult-2 would ensure that temporary and permanent impacts would
remain less than significant.
No major changes to the project area or the general scope and magnitude of the project components
have taken place since preparation of the 2008 DMP Update EIR that would require revisions to the
analysis in the EIR. There is no information in the record or otherwise available that indicates that there
are substantial changes in circumstances pertaining to cultural resources that would require major
changes to the 2008 DMP Update EIR.
This Addendum has analyzed all available relevant information to determine whether there is new
information that was not available at the time the 2008 DMP Update EIR was certified, indicating that a
new significant effect not reported in that document may occur. Based on the information and analyses
above, there is no substantial new information indicating that there would be a new significant impact
related to cultural resources requiring major revisions to the 2008 DMP Update EIR.
With Mitigation Measures Cult-1 and Cult-2, potentially significant impacts would be reduced to a level
below significance. There is no new information, mitigation, or alternatives to the project that would
substantially reduce either of the potentially significant impacts pertaining to cultural resources
identified and considered in the 2008 DMP Update EIR.
With regards to potential cultural resource impacts, the New and Revised Project Components are
within the scope of the 2008 DMP Update EIR. None of the conditions under Section 15162 requiring a
subsequent EIR have been met.
3.14 PALEONTOLOGICAL RESOURCES
3.14.1 Previous Analysis
The analysis of the impacts to paleontological resources for the 2008 DMP Update is contained in the
2008 DMP Update EIR, Section 4.12, pages 4.12-1 to 4.12-7. Cumulative impacts related to cultural
resources are discussed in Section 5.2.1.12 on page 5.1-16 of the 2008 DMP Update EIR. With respect to
the programmatic evaluation of the impacts of the PLDA Project Components, the EIR made the
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following conclusion (mitigation measures referenced have been included in Appendix C of this
Addendum):
1) Impact Paleo-1: For 2008 DMP Update components proposed in locations
considered to have moderate to high sensitivity for paleontological resources (to be
determined during project-specific design), grading and earthwork could disturb
potentially unknown fossil remains and the information in the fossils could be lost.
Impacts would be considered potentially significant.
Mitigation Measure Paleo-1 shall be implemented during construction of PLDA and
non-PLDA project components proposed in geologic formations with a moderate to
high sensitivity for paleontological resources, including Unnamed Marine Terrace
Deposits, Unnamed River Terrace Deposits, Santiago Formation, Del Mar Formation,
Point Loma Formation, Lusardi Formation, and Undifferentiated Santiago Peak
Volcanics. Determination of the underlying geologic formations shall be determined
during project design through existing mapping, project-specific geotechnical
investigations, or other appropriate testing methods. Implementation of these
measures will reduce impacts to paleontological resources to below a level of
significance.
3.14.2 Analysis of the Project Changes
Section 4.12.1.1 (pages 4.12-1 to 4.12-3) of the 2008 DMP Update EIR describes various geologic
formations that are considered moderately to highly sensitive for paleontological resources. In support
of this Addendum, a review of the general underlying geologic formations was conducted for the New or
Revised Project Components and subsequently compared the Paleontological Sensitivity Model found in
Section 6.4 of the Carlsbad Tribal, Cultural, and Paleontological Resources Guidelines (City of Carlsbad
2017). Table Q indicates the paleontological sensitivity mapped at or near New or Revised Project
Components.
Table Q: Paleontological Sensitivity at New or Revised Project Components
Project Component
ID1 Name Paleontological Sensitivity2
Basin A – Buena Vista Creek Watershed
BCV-1 Jefferson Street North High
BVC-2* Jefferson Street South High
BVC-3* Marron and Monroe Drainage
Improvements
Potentially high, located near the boundary between low
and high sensitivity areas
BVC-4* Marron and Jefferson Multi-Benefit
Basin
Likely high, mapped as within lagoon but adjacent areas
are high sensitivity
BVC-5* Laguna Drive Storm Drain Upsize High
Basin B – Agua Hedionda Creek Watershed
BJ-1 Rancho Carlsbad Multi-Benefit Basin Moderate, located near boundary of areas mapped as low
and high
ACH-2 College Boulevard Storm Drain
Extension Low, located near boundary of areas mapped as moderate
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Table Q: Paleontological Sensitivity at New or Revised Project Components
Project Component
ID1 Name Paleontological Sensitivity2
ACH-3 Cantarini and Holly Springs Culvert Low, located near boundary of areas mapped as moderate
ACH-4* Park Drive and Hillside Drive Storm
Drain Upsize
Potentially high, located near the boundary between low
and high sensitivity areas
Basin C – Encinas Creek Watershed
EC-1 Paseo Del Norte Box Culvert High
Basin D – San Marcos Creek Watershed
SMC-1 Batiquitos Lagoon Stormwater
Treatment System Low, located near boundary of areas mapped as moderate
1 Project Components marked with * are New Project Components.
2 Paleontological sensitivity is based on a review of the Paleontological Sensitivity Model in the Carlsbad Tribal, Cultural, and
Paleontological Resources Guidelines and geological information from the California Department of Conservation, California Geological
Survey.
3.14.2.1 Direct and Indirect
Similar to the 2008 DMP Update as described in Section 4.12.3.1 (page 4.12-4), construction of the New
or Revised Project Components may require excavation within potential fossil-bearing geologic
formations, which could potentially impact sensitive paleontological resources. Project-specific
information regarding underlying formations would become available during design through the
geotechnical analysis required as one of the project design features in Table 3-6 of the 2008 DMP
Update EIR (included in Appendix C of this Addendum). Although some project components would be
constructed in previously-disturbed areas, some of the New or Revised Project Components have the
potential to result in potentially significant impacts to paleontological resources. In addition to the
project design features/methods and construction measures identified in Table 3-6 of the 2008 DMP
Update EIR, Mitigation Measure Paleo-1 requires mitigation, monitoring, and recovery of significant
paleontological resources (if any) for projects that are determined to require excavation into intact
geologic formations with moderate to high sensitivity (note that the mitigation measure is consistent
with guidelines that have been subsequently adopted by the City; refer to Section 3.14.3 for additional
information). Implementation of Mitigation Measure Paleo-1 will reduce impacts to paleontological
resources to below a level of significance. No changes are needed to the impact conclusions in the 2008
DMP Update EIR presented in Section 3.14.1; impacts would be less than significant with mitigation
incorporated.
3.14.2.2 Cumulative
The 2008 DMP Update EIR found that although project components, along with other development
projects, could have potentially significant impacts to paleontological resources, these types of impacts
are localized and can be addressed through the implementation of feasible mitigation measures.
Impacts to paleontological resources from DMP project components would be reduced through
implementation of the project design features/methods and construction measures in Table 3-6 of the
2008 DMP Update EIR and Mitigation Measure Paleo-1. These measures would reduce impacts to a
level below significance, and there would not be a considerable contribution to a significant cumulative
paleontological resources impact. The New or Revised Project Components would have comparable
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January 2026 3-57 Addendum
impacts to paleontological resources as those in the 2008 DMP Update, and there would be no change
in the cumulative impact determination. The Project Changes would not result in a considerable
contribution to a significant cumulative impact to paleontological resources.
3.14.3 Substantial Changes with Respect to Circumstances or New Information of Substantial
Importance
As described in Section 3.13.3 of this Addendum, since the certification of the 2008 DMP Update EIR, the
City has adopted the Carlsbad Tribal, Cultural, and Paleontological Resources Guidelines (City of Carlsbad
2017). New or Revised Project Components would be subject to the requirements set forth in these
guidelines at the time project-level review is conducted. The information regarding paleontological
sensitivity provided in Section 3.14.2 is consistent with the requirement in the guidelines that results of
the sensitivity model review be included in the CEQA document (Section 10.1 of the Carlsbad Tribal,
Cultural, and Paleontological Resource Guidelines). Mitigation Measure Paleo-1 identified in the 2008
DMP Update EIR is consistent with the guidelines that have since been adopted by the City. Specifically,
Paleo-1 sets forth the circumstances under which the measure would apply, pre-construction
requirements for confirming the determination of underlying geologic formations, preparation and
implementation of a monitoring program, requirements for salvage and preservation, documentation,
and reporting. These actions are also addressed in the City’s adopted guidelines. As plans for each
project component are submitted for discretionary approval, the City may opt to incorporate language
from the adopted guidelines, which would cover all actions identified in Mitigation Measure Paleo-1. As
the 2008 DMP Update EIR also acknowledged potential impacts to fossil-bearing geologic formations
and included mitigation to address potential impacts to significant paleontological resources, the results
of the sensitivity model do not represent new information of substantial importance or result in
substantial changes with respect to the circumstances under which the project is being undertaken.
No other changes have been identified with respect to the circumstances under which the Project
Changes would be undertaken, and there is no new information of substantial importance that has
become available relative to paleontological resources.
3.14.4 Conclusion
Based on the foregoing analysis and information, there is no evidence that the New or Revised Project
Components require a major change to the 2008 DMP Update EIR. The Project Changes would not result
in new significant environmental impacts related to paleontological resources, and there would not be a
substantial increase in the severity of impacts described in the 2008 DMP Update EIR. Implementation
of the project design features/methods and construction measures identified in Table 3-6 of the 2008
DMP Update EIR (included in Appendix C of this Addendum) and Mitigation Measure Paleo-1 would
ensure that temporary and permanent impacts would remain less than significant.
With regards to potential paleontological resource impacts, the New and Revised Project Components
are within the scope of the 2008 DMP Update EIR. None of the conditions under Section 15162 requiring
a subsequent EIR have been met.
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
Addendum 3-58 January 2026
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Carlsbad Drainage Master Plan Update
CIP Project No. 6623
January 2026 4-1 Addendum
4.0 REFERENCES
California Air Resources Board (CARB). 2024. iADAM: Air Quality Data Statistics. Website:
www.arb.ca.gov/adam (accessed October 31, 2024).
California Department of Conservation (DOC), California Geological Survey. 2010. GCS Special Report
217, Plate 11. Geologic Compilation of Quaternary Surficial Deposits in Southern California,
Onshore Portion of the Oceanside 30’ × 60’ Quadrangle. July 2010.
California Department of Conservation (DOC), California Geological Survey. 2021. Webservice of
Official Maps of Alquist-Priolo Earthquake Fault Zones. Updated September 29, 2021.
Website: https://maps.conservation.ca.gov/geologichazards/#dataviewer (accessed October
25, 2021).
California Department of Conservation (DOC), Division of Land Resource Protection. 2018. Farmland
Mapping and Monitoring Program. Website: https://maps.conservation.ca.gov/dlrp/ciff/
(accessed October 24, 2021).
California Department of Conservation (DOC), Division of Land Resource Protection. 2017. State of
California Williamson Act Contract Land.
California Department of Fish and Wildlife (CDFW). 2020. California Natural Diversity Database.
RareFind 5 (Version 5.2.14). Website: https://www.wildlife.ca.gov/Data/CNDDB/Maps-and-
Data (accessed August 2021).
California Native Plant Society (CNPS), Rare Plant Program. 2021. Inventory of Rare and Endangered
Plants of California (online edition, v9-01 1.0). Website: https://www.rareplants.cnps.org
(accessed August 2021).
California Regional Water Quality Control Board (RWQCB), San Diego Region. 2015. National
Pollutant Discharge Elimination System (NPDES) Permit and Waste Discharge Requirements
for Discharges from the Municipal Separate Storm Sewer Systems (MS4s) Draining the
Watersheds Within the San Diego Region. Order No. 2013-0001, as amended by Order Nos.
R9-2015-001 and R9-2015-0100, NPDES No. CAS0109266. Amended November 18, 2015.
City of Carlsbad. 1986. City of Carlsbad Growth Management Program Citywide Facilities and
Improvements Plan. Amended August 22, 2017.
City of Carlsbad. 1997. Aviara Master Plan. Dated July 1997. Website: https://www.carlsbadca.gov/
home/showpublisheddocument/6938/637614188516530000 (accessed June 10, 2025).
City of Carlsbad. 2004. Habitat Management Plan for Natural Communities in the City of Carlsbad.
Dated November 2004. Website: https://carlsbadca.prod.govaccess.org/home/show
document?id=1600 (accessed October 27, 2021).
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
Addendum 4-2 January 2026
City of Carlsbad. 2007. Final Environmental Impact Report for the City of Carlsbad Drainage Master
Plan Update, EIR #04-02/SCH No. 2006041066 and Appendices. December 11, 2007.
City of Carlsbad. 2008. City Council Meeting Agenda August 5, 2008.
City of Carlsbad. 2008. City Council Resolution No. 2008-229 August 5, 2008.
City of Carlsbad. 2008. City of Carlsbad Agenda Bill City of Carlsbad Drainage Master Plan and
Planned Local Area Fees/Calavera and Agua Hedionda Creeks Project EIR 04-02/MCA07-01/
LCPA 07-06. AB# 19,540. August 5, 2008.
City of Carlsbad. 2015. General Plan. Approved on September 22, 2015. Website: https://www.
carlsbadca.gov/departments/community-development/planning/general-plan (accessed
October 27, 2021).
City of Carlsbad. 2017. Carlsbad Tribal, Cultural, and Paleontological Resources Guidelines. Prepared
by ECORP Consulting, Inc. with contributions from Cogstone Resource Management.
September.
City of Carlsbad. 2019. Local Coastal Program. Dated October 16, 2019.
City of Carlsbad. 2019. Local Coastal Program Land Use Plan. Dated September 2019.
City of Carlsbad. 2019. Village and Barrio Master Plan. Date October 2019. Website: https://www.
carlsbadca.gov/home/showpublisheddocument/19976/638750584975700000 (accessed
June 10, 2025).
City of Carlsbad. 2021. 2021 Housing Element Update Addendum. Dated February 2021.
City of Carlsbad. 2022. Strategic Plan 2023-2027. Dated October 2022. Website: https://www.
carlsbadca.gov/home/showpublisheddocument/11580/638612057801730000 (accessed
June 10, 2025).
City of Carlsbad. 2023. Vehicle Miles Traveled (VMT) Analysis Guidelines. Dated May 3, 2023.
Website: https://www.carlsbadca.gov/home/showpublisheddocument/312/638816039777
170000 (accessed June 10, 2025).
City of Carlsbad. 2024. 2021-2029 Housing Element.
City of Carlsbad. 2024. Climate Action Plan. Dated November 2024. Website: https://www.carlsbad
ca.gov/home/showpublisheddocument/19484/638717809348600000 (accessed June 10,
2025).
City of Carlsbad. 2024. General Plan Land Use Map. Updated July 2024. Website: https://www.
carlsbadca.gov/home/showpublisheddocument/246/638636302563830000 (accessed
October 27, 2021
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
January 2026 4-3 Addendum
City of Carlsbad. 2025. Municipal Code. Website: https://ecode360.com/CA4913/home. Title 8,
Section 8.48.020 Noise Ordinance, Title 15 Grading and Drainage and Title 18 Building Codes
and Regulations (accessed June 10, 2025). Title 19 Environmental Protection Procedures
(accessed June 10, 2025).
City of Carlsbad. About Growth Management. Website: https://www.carlsbadca.gov/departments/
community-development/growth-management/about-growth-management (accessed
August 15, 2025).
Federal Emergency Management Agency (FEMA). 2021. National Flood insurance Program Flood
Insurance Rate Map. Panels 0761, 0762, 0764, 0768, 0769, and 1032. Exported from
National Flood Hazard Layer on September 24, 2021.
Federal Highway Administration (FHWA). 2006. Roadway Construction Noise Model.
Federal Transit Administration (FTA). 2018. Transit Noise and Vibration Impact Assessment Manual.
FTA Report No. 0123. September 2018.
Governor’s Office of Planning and Research (OPR). 2018. Technical Advisory on Evaluating
Transportation Impacts In CEQA.
Rick Engineering. 2025. City of Carlsbad Draft Drainage Master Plan.
San Diego County Air Pollution Control District (SDAPCD). 2025. Attainment Status. Website:
https://www.sdapcd.org/content/sdapcd/planning/attainment-status.html (accessed June
10, 2025).
State Water Resources Control Board (SWRCB), Division of Water Quality. 2010. National Pollutant
Discharge Elimination System (NPDES) General Permit for Storm Water Discharges
Associated with Construction and Land Disturbance Activities. Order No. 2022-0057-DWQ.
NPDES No. CAS000002.
United States Environmental Protection Agency (USEPA). 2024. Air Data: Air Quality Data Collected
at Outdoor Monitors Across the U.S. Website: https://www.epa.gov/outdoor-air-quality-
data (accessed October 31, 2024).
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
Addendum 4-4 January 2026
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Carlsbad Drainage Master Plan Update
CIP Project No. 6623
January 2026 Addendum
APPENDIX A
PROJECT SHEETS
[
I
Carlsbad Drainage Master Plan Update
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Addendum January 2026
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Date of Exhibit: 1/14/2026SANGIS/SANDAG Aerial Imagery, 2023
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Carlsbad Drainage Master Plan Update
CIP Project No. 6623
Addendum January 2026
This page intentionally left blank
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
January 2026 Addendum
APPENDIX B
EXCERPTS FROM 2008 DMP UPDATE EIR
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
Addendum January 2026
This page intentionally left blank
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
January 2026 B-1 Addendum
EXCERPTS FROM THE 2008 DMP UPDATE EIR
DESCRIPTION OF PLDA PROJECT COMPONENT TYPES (EIR PAGES 3-11 AND 3-12)
3.3.2 PLDA Project Components
The PLDA project components proposed in the 2008 DMP Update involve modifications and
improvements to existing storm drain infrastructure and drainage areas, as well as construction of
additional infrastructure required to accommodate storm flows resulting from future development
within the city. PLDA projects included in the 2008 DMP Update would involve drainage infrastructure
components and activities including:
x reinforced concrete pipe (RCP) (enclosed RCP for conveyance of storm water);
x concrete trapezoidal channels (open steel reinforced concrete channels for conveyance of storm
water);
x soft bottom trapezoidal channels (open earth-bottom channel with earthen or rock sides for
conveyance of storm water);
x drainage inlets (concrete structures that collect surface water through a side opening or grate);
x manhole cleanouts (concrete access openings, measuring 36 inches or less in diameter, that allow
maintenance of shallow culverts or pipelines);
x junction structures (concrete access openings that allow maintenance of large-diameter culverts
[trunk lines greater than 36 inches] or pipelines);
x perforated subdrains (trench with perforated pipe near the bottom that allows rapid transport of
water);
x gabion structures (woven wire mesh baskets containing stone that reduce water velocity and
erosion and are used as soil-retaining structures, weirs, or drop structures);
x sediment basins (impoundment structures designed to promote longer detention time to allow for
deposition of sediment within the basin and remove sediment from water prior to release);
x water quality basins (impoundment structures designed to control on-site and channel runoff and
reduce sediment and pollutant loading, and may also include vegetation to enhance filtration and
erosion control);
x erosion and scour protection (energy dissipation devices, such as berms, rock slope protection, or
concrete impact dissipation units, that have the ability to reduce erosive velocities and the potential
of runoff to carry away material from a channel bed or bank through mechanical means);
x slope stabilization (treatment measures that prevent dislodging of soil material from an inclined soil
surface, such as chemical emulsifiers, mechanical stabilizers [e.g., geo-grids], or vegetative
treatment);
x installation of Vmax (slope stabilization matting to reinforce slopes and vegetation); and
x bridge construction (installation of bridge components including roadway decks and support piers,
and construction of approaches and bridge abutments).
Table 3-1 provides a list of proposed PLDA projects that have been identified to date by the City. These
identified projects have not yet been designed. The locations of these proposed projects are shown in
Figures 3-1 through 3-4.
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
Addendum B-2 January 2026
DISCUSSION OF POTENTIAL FUTURE PROJECT COMPONENTS (EIR PAGE 3-24)
3.3.4 Future DMP Project Components
As development proceeds in Carlsbad, the City may determine that additional drainage improvements
or facilities are necessary to accommodate storm flows, maintain storm water quality, provide flood
protection, and improve pedestrian and vehicular safety in addition to the proposed components
described above in Sections 3.3.2 and 3.3.3. It is anticipated that any additional drainage improvements
or facilities would involve similar construction and operation activities as those currently identified in
the 2008 DMP Update. The 2008 DMP Update includes project components that may be determined
necessary for the City to ensure that the objectives of the 2008 DMP Update are met. While the exact
details of additional individual project components are not known at this juncture, their general
characteristics would be similar to project components described in Sections 3.3.2 and 3.3.3. As
described in Section 1.4, potential future projects would require evaluation under CEQA to determine if
the proposed future actions and project features are covered by the analysis in this EIR. However, if a
potential future project would involve actions or project features beyond those evaluated in this EIR,
that project would require additional CEQA documentation.
The environmental analysis in this EIR specifically addresses project components identified in the 2006
2008 DMP Update. As noted in Section 1.4, project components addressed at a program level within this
EIR would be subject to a subsequent CEQA review process to determine whether the analysis provided
in this document is adequate. Future 2008 DMP Update components would be subject to the same
CEQA review process. If it is determined that a proposed component has been adequately addressed
within this EIR, project design features/methods and applicable mitigation measures would be
incorporated into the project as a condition of project approval. If the environmental analysis in this EIR
is determined to not adequately address potential impacts associated with a future 2008 DMP Update
component, subsequent CEQA analysis would be required.
DESCRIPTION OF PLDA CONSTRUCTION ACTIVITIES (EIR PAGES 3-24 THROUGH 3-27)
3.3.5 Potential Project Design Features/Methods and Construction Activities
This section provides a brief overview of the types of general activities proposed in the 2008 DMP
Update related to PLDA and non-PLDA project components, as well as some typical construction
features associated with such activities. While some PLDA and non-PLDA project components and
potential future components would involve these types of activities, others may require additional
project-specific design features and construction measures, which would be identified during the project
design phase.
Pipeline Construction
Pipeline (generally RCP) would be installed by open trench construction primarily in existing roads
and/or drainages. In areas of existing roadways, open trench construction would typically involve saw-
cutting the existing street pavement slightly wider than the required pipe trench width. Excavation is
usually accomplished by backhoe to remove material to the required pipe depth. Where the pipeline
may be constructed in fractured rock, it may be necessary to jackhammer or blast to prepare a deep
enough trench. Any explosives used for blasting would be imported to the site on a daily basis and no
storage would occur on-site.
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
January 2026 B-3 Addendum
The placement and surface restoration of approximately 150 LF (linear feet) of pipe per day can occur.
Across intersections, installation is typically limited to 50 LF per day. An average distance of 100 feet per
day is assumed for construction scheduling purposes.
Jack and bore construction is an optional technique that may be used for pipeline construction in areas
that cannot be interrupted by open trench or similar construction methods. This technique can be used
beneath creeks/streams and in areas with high traffic volumes, such as busy intersections. This
construction method involves boring a large enough hole to jack a carrier pipe through it. The service
pipe is then inserted through the carrier pipe. For each bore and jack location, a jacking pit
(approximately 10 feet wide by 30 feet long) and a receiving pit (approximately 10 feet wide by 10 feet
long) would be excavated and then backfilled after completion of pipe installation.
Tunneling is another construction method that may be used to install pipelines. Tunneling would require
greater excavation dimensions, resulting in significantly higher costs than boring and jacking. This
technique would only be utilized for special situations; for example, in areas with sensitive receptors,
habitat, or other environmentally constrained areas in which surface disturbance should be avoided.
Storm Drain Infrastructure Construction/Improvements
Construction or retrofits of storm drain infrastructure, including concrete trapezoidal channels, drainage
inlets, manholes, junction structures, gabion structures, and sediment and water quality basins, could be
associated with proposed 2008 DMP Update facilities. Construction or retrofit of these features would
generally be conducted concurrently with other activities, such as pipeline construction or retrofit or
existing drainage channel enhancement to minimize disturbance.
Existing Channel Enhancement
Enhancement/improvements to existing drainage channels could involve activities similar to Type 1 and
Type 2 operation and maintenance activities described in detail in Section 3.3.6 below.
Erosion and Scour Protection
Erosion and scour protection for 2008 DMP Update facilities would potentially involve implementation
of erosion control devices adjacent to proposed or existing culverts or bridges (e.g., fiber rolls, wattles,
mats, erosion control blankets, rock slope protection, silt fences, hydroseed, etc.). Check dams and
stilling basins require excavating soil within the wash or channel and its bank and placing concrete or
rock slope protection (bank armoring). Typical material used for the placement of rock slope protection
would be either Class II base or riprap (18-inch-diameter). This activity would be accomplished with a
backhoe, loader, gradall, and/or small dozer. Sediment catch basins could require excavating areas on
the inlet side of culverts or ditches, and constructing dikes to direct the flow of water.
Bridge Construction/Rehabilitation
Bridge construction would involve installing bridges and piers, which would require excavation. Bridge
rehabilitation consists of replacing components; reconstructing approaches, bridge abutments, or
column protection; applying a seal coat; or sand blasting the underside of the bridge to inspect for
damage. Temporary access roads may be required to access underneath bridge structures. Some bridge
construction or rehabilitation work may also require installing temporary traffic detours across existing
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
Addendum B-4 January 2026
roadways or bridges; detours would include construction of temporary drainage features to divert
runoff from the construction site.
Dredging and Sediment Removal
Erosion from storm water runoff results in an accumulation of sediment around existing downstream
drainage facilities, thereby reducing hydraulic flow of these facilities. To maintain flow in existing
drainage facilities, it is necessary to periodically remove accumulated sediment. The removal of
sediment would be limited to the minimum necessary to restore the waterway hydraulic design flow in
the immediate vicinity of the drainage facility but would not extend outside existing channel or
inlet/outlet structures. Dredging of sediment would typically be conducted by a gradall and/or backhoe
from the roadway shoulder. Where feasible, an articulating front end loader (i.e., Caterpillar 950) would
be used. The bucket would be extended down and sediment or debris would be scooped out, avoiding
the discharge of fill into the waterway. Sediment and debris would then be placed in haul trucks and
disposed of in approved locations. At drainage inlets or junction structures, where confined space limits
access to larger equipment, vactor trucks would be utilized to vacuum out sediment or debris. In
addition, sediment could also be removed from small cross culverts or in specified channel locations
with the use of hand tools.
Construction Schedule, Staging Areas, and Traffic Control
Implementation of the 2008 DMP Update would occur over an anticipated 30-year plan horizon. As
development in Carlsbad progresses, project components required to accommodate new storm flows
generated from anticipated development would be implemented. The City would ultimately determine
the appropriate timeframe for implementation of individual projects based on infrastructure needs and
approval of new developments. Specific schedules for individual projects would be determined at the
project design phase. Staging areas would be determined for proposed project components prior to the
commencement of construction, but for purposes of this program level analysis, all are assumed to be
located in disturbed areas. Temporary access roads would be required during construction of some
project components. Access roads would generally be gravel and constructed adjacent to project sites
within the project footprint to allow for construction equipment access, inspections, and maintenance.
For purposes of this analysis, it is assumed that access roads would be located in disturbed areas.
DESCRIPTION OF OPERATION AND MAINTENANCE ACTIVITIES (EIR PAGES 3-27 TO 3-32)
3.3.6 Operation and Maintenance
Operation and maintenance of existing and proposed drainage facilities are an essential component for
the proper and efficient function of city infrastructure. While operation and maintenance activities
would be anticipated for all city drainage facilities, including both PLDA and non-PLDA 2008 DMP Update
components, these proposed activities are long-term commitments that would not be paid for by
private developers and would therefore not receive funding from the PLDA fee program.
Proposed operation and maintenance activities have been grouped into the following categories, which
are more fully described below. The categories include some project design features and methods
typical of operation and maintenance activities.
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
January 2026 B-5 Addendum
(1) Inlet/Outlet and Channel Maintenance
(2) Existing Facilities Repair
(3) Facility Rehabilitation/Upgrades (Non-capacity Related)
(4) Culvert Replacement and Roadway Rehabilitation
(5) Bridge Rehabilitation/Replacement
(6) Storm Drain Infrastructure Repair
(7) Sedimentation/Retention/Water Quality Basin Maintenance and Repair
(8) Jurisdictional Dam Operation and Maintenance
Type 1: Inlet/Outlet and Channel Maintenance
Routine maintenance activities are necessary within inlet/outlet structures, as well as channels
themselves. Activities could include vegetation control (native and nonnative species); tree trimming;
and/or debris removal including trash, rock, and sediment removal. Maintenance required for the
control of vegetation, sand, silt, debris, and other obstructions to outlets would typically be conducted
on an annual basis; however, these activities may be performed more frequently as areas of concern are
reported throughout the season.
Vegetation control is required within drainage facility bottoms, banks, and roads to maintain drainage
design flow or to conduct facility inspections. Vegetation control within drainage facilities would
typically be conducted using mechanical means, manual labor, or chemical application. Mechanical
means include using equipment such as a gradall and/or backhoe along the roadway shoulder, which
removes vegetation in a manner that avoids fill activity (e.g., scooping with bucket). Material would be
placed in haul trucks and disposed of in approved locations. Manual labor includes the use of handheld
tools such as chainsaws, mechanical mower, shovels, etc. Chemical application would be conducted
infrequently and only in dry conditions. Application would only be used in areas surrounding guardrails,
signs, and dry ditches where flow is restricted to the point that the roadway may become flooded.
The removal of trees or branches in imminent danger of falling or likely to fall during high flows, fallen
trees obstructing flow, and associated debris would be performed on an as-needed basis. Trimming,
pruning, shaping, or removal of trees would be conducted by a qualified tree trimmer. Stumps would be
removed to 8 inches below the surface, when necessary.
Trash and debris clearing is necessary at inlets/outlets and within channels to maintain drainage facility
design capacity. Trash and debris would be removed with mechanical equipment from the roadway
shoulder or by manual labor. The removal of sediment and trimming of vegetation typically extends less
than 20 feet from the pipe inlet/outlet to minimize impacts to the surrounding environment.
In addition to the removal of vegetation, trash, and debris, accumulated sediment impacting hydraulic
capacity may be removed from inlets and outlets using the methods described above in Section 3.3.5.
Type 2: Existing Facilities Repair
Repairs to existing facilities include work related to storm drains, culverts, inlets/outlets, channels, brow
ditches, basins, and existing erosion control features (e.g., fiber rolls, silt fences, erosion control
blankets, hydroseed, and structural Best Management Practices [BMPs], such as sediment/detention
basins, biostrips, bioswales, and check dams). Activities for roadway repair associated with drainage
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
Addendum B-6 January 2026
structures include leveling of soil surface, filling ruts, and repairing the roadway shoulder or dike. This
work would typically be completed from the adjacent lane of the roadway and would not extend outside
of the paved shoulder, with the exception of pulling out excess deposition or material washed from
adjacent slope areas. It could also be necessary to perform mechanical repair or replacement of
structural BMPs, including revegetating biostrips and bioswales. Facility repair could also include, but
not be limited to, repairing scoured channel bottoms, bridge piers and abutments, damaged headwalls,
concrete aprons, damaged spillways, curb inlets, brow ditches, broken pipes, and energy dissipaters.
Repairs to paved channel bottoms are currently conducted by using a front-end loader, trackhoe,
backhoe, or a small dozer. While some of the equipment can work from the side of the roadway to
access the channel, some work may be needed in the channel itself depending on accessibility, the size
of the channel, etc. Repair of unpaved channel bottoms could include the installation of riprap or
concrete lining, depending on the amount of damage. Rock/riprap removal and placement would be
most commonly conducted using a front-end loader or a motor grader, and work could be accomplished
from the roadway shoulder by either picking up or placing rock/riprap into/from the channel.
Type 3: Minor Facility Rehabilitation/Upgrades (Non-capacity Related)
Facility upgrades include projects such as minor sediment/detention basin upgrades (i.e., improvements
may result in minor increase in size and/or depth for maintenance purposes only), culvert replacements
(increase in size, diameter, or type of culvert), culvert slip lining (to maintain line and grade where
feasible), access to drainage facilities, construction and upgrades to erosion control features and
structural BMPs, and implementation of new erosion control devices adjacent to existing culverts or
bridges (fiber rolls, mats, erosion control blankets, rock slope protection, silt fences, hydroseed, etc.).
Check dams and stilling basins require excavating soil within the wash or channel and its bank, and
placing concrete or rock slope protection (bank armoring). Typical material used for the placement of
rock slope protection would be filter fabric with a Class II backing (3- to 6-inch diameter) and riprap (18-
inch-diameter or greater). This activity would be accomplished with a backhoe, loader, gradall, and/or
small dozer. Temporary access to the channel may be necessary. Sediment catch basins could require
excavating areas on the inlet side of culverts or ditches, and constructing dikes to direct the flow of
water.
Type 4: Culvert Replacement and Roadway Rehabilitation
Culvert replacement and roadway rehabilitation consist of replacing/retrofitting failed culverts with the
same size/diameter culvert and extending culverts. In addition, rock slope protection may be included to
minimize runoff velocities at the outfall. Replacement work typically requires excavation above existing
pipes, removing and replacing pipes, and backfilling new culverts with a paved roadway section. The
roadway section would be constructed of asphalt, concrete, or Portland cement to match existing
conditions. Rock slope protection would typically be placed at the outfall of the culvert to aid in velocity
reduction, thereby minimizing scour downstream. Temporary access routes and staging areas used for
equipment, as well as material storage and spoils disposal, would also be included.
Type 5: Bridge Rehabilitation/Replacement
Bridge rehabilitation consists of replacing crossing surfaces or decks; reconstructing approaches, bridge
abutments, and column protection; applying a seal coat; and sand blasting the underside of the bridge
to inspect for damage. In addition, replacement of dikes, barrier rails, and other appurtenances that
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
January 2026 B-7 Addendum
direct runoff to an inlet must be maintained to prevent runoff from ponding and creating a safety hazard
along roadways. Bridge replacement consists of removing and replacing entire bridge structures and
pillars with a new bridge structure, activities that require excavation. Temporary access roads may be
required to access the area underneath bridge structures. Some bridge rehabilitation work may require
installing temporary traffic detours across the bridge; detours would include construction of drainage
structures to divert runoff from the construction site.
Type 6: Storm Drain Infrastructure
Curb inlets and junction structure replacement consists of replacing/retrofitting damaged or aging
drainage inlets, sidewalk underdrains, manholes, and junction structures with the same size facility to
provide safe access for maintenance personnel. Storm drain structure replacement consists of removing
and replacing the entire structure and its appurtenances with a new drainage inlet, manhole, and/or
junction structure. Removal of these features requires excavation and would be accomplished with a
backhoe, loader, gradall, and/or small dozer. Excavation activities would be limited to previously
excavated areas. Backfill with Class II base, formwork, and concrete work would also be required to
complete the task.
Type 7: Sedimentation/Retention/Water Quality Basin Maintenance and Repair
Basin maintenance and repair typically consist of removal activities such as vegetation and debris
removal, including trash and other material. Maintenance required for concrete-lined basins includes
the use of epoxy sealant, concrete patching of damaged areas, cleaning or replacement of inlet and
outlet structures, and graffiti removal. Inspections and repairs are conducted on an annual basis;
however, these activities may be performed more frequently since they depend on the amount of
rainfall received during the season.
Maintenance required for unlined basins includes the removal of vegetation, sand, silt, debris, and other
material. Maintenance typically requires the use of a gradall and/or backhoe for sediment removal.
Where feasible, an articulating front end loader (i.e., Caterpillar 950) would be used and the removal of
sediment would be needed to restore the basins to their design capacities. Sediment and debris would
be removed, placed in haul trucks, and disposed of in approved locations. Side slopes would be repaired
as needed.
Type 8: Jurisdictional Dam Operation and Maintenance
Dam maintenance typically includes inspections, repairs, rehabilitation and/or improvements, and
documentation of all observations and activities. General inspections of outlet pipes and structures for
leaks and deterioration, telemetry equipment, pumps, water treatment facilities, BMPs, and spillways
are typically carried out as part of a systematic inspection process. Other maintenance repairs and
general housekeeping activities include minor channel and bank stabilization, resurfacing embankment
slopes, trash and debris removal, and vegetation removal within the dam embankment and around the
emergency spillway. Maintenance activities may also include rodent abatement, as well as trimming and
removal of vegetation from access roads to the spillway and associated structures.
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
Addendum B-8 January 2026
Rehabilitation and/or improvements include repairing the top and face of the dam structure and
associated maintenance access roads; painting; lubrication or replacement of structural and/or
mechanical components such as gates, valves, or piping; and replacement of electrical equipment.
Dam operational activities include the “exercise of valves,” which encompasses the opening and closing
of pipe valves to raise and lower the water surface elevation of impounded water. Testing of primary, as
well as secondary, equipment for drawdown of water is essential to the health and operation of the
dam.
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
January 2026 Addendum
APPENDIX C
PROJECT FEATURES/METHODS/REQUIREMENTS AND MITIGATION
MEASURES FROM THE 2008 DMP UPDATE EIR
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
Addendum January 2026
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Project Name: Carlsbad Drainage Master Plan Update
CIP Project No. 6623
January 2026 C-1 Addendum
PROJECT FEATURES/METHODS/REQUIREMENTS (TABLE 3-6, EIR PAGES 3-49 TO 3-54)
Table 3-6: Summary of Project Design Features/Methods, Agency Requirements, and Construction
Measures
Topic Project Design Features/Methods and Construction Practices
Land Use x Prior to the first preconstruction meeting for each component, the City shall verify that the
following measures are incorporated into the construction specifications and plans:
x Prior to initiation of construction-related activity, the biologist shall oversee installation of
temporary fencing along Coastal Zone/HMP boundaries adjacent to constructing/staging areas.
Such fencing shall be clearly shown on construction drawings provided to the contractor.
x Vehicles shall use existing roads or identified routes to access the construction site, unless new
access routes (e.g., for channel maintenance) are approved. No unauthorized new or temporary
access routes shall be constructed. All access routes shall be clearly marked (e.g., flagged, staked)
prior to construction and shown on construction drawings provided to the contractor.
x Storage of construction equipment/materials, parking, or other construction-related activities
shall occur within the designated contractor staging areas as shown on the construction drawings
provided to the contractor.
x The contractor shall ensure that fueling of equipment/vehicles occurs only within the designated
contractor staging areas as shown on the construction drawings or on paved roadways at a
minimum distance of 50 feet away from the HMP. Appropriate catchment basins/devices shall be
used to prevent the flow of fuel. Construction equipment shall be checked for leaks prior to
operation and repaired as necessary.
Visual Resources x For proposed projects involving the construction of bridges or other visually obtrusive structures
(such as concrete drainages) adjacent to undeveloped areas, the City shall be required to submit
site design plans to the Planning Director (PD) of the Planning Department for environmental
review prior to project approval. The PD shall verify that the proposed bridge or structure design
would not obstruct scenic vistas or degrade views along designated scenic corridors.
x Demolition debris and excavated material shall be removed in a timely manner for off-site
disposal.
x Projects involving vegetation removal and/or clearing in undeveloped areas or along designated
scenic corridors shall be required to submit design plans to the PD for review prior to project
approval. Design plans shall be consistent with the El Camino Real Corridor Design Standards
and/or General Plan policies for designated scenic corridors, where applicable. Tree and
vegetation removal shall be limited to removal depicted on design plans. The PD shall verify that
the project retains sufficient vegetation to provide adequate screening to sensitive receptors or
that landscaping along the corridor is incorporated into project design. Landscaping shall include
appropriate species to enable screening for receptors along the undeveloped area or designated
corridor, such as trees that mature at an adequate height to provide a visual buffer along raised
portions of roadway.
x Construction lighting shall be shielded or directed away from adjacent residences and sensitive
receptors to light, including sensitive habitats.
x All roadway features (signs, pavement delineation, roadway surfaces, etc.) and structures within
City and private rights-of-way shall be protected, maintained in a temporary condition, or
restored.
Transportation/
Circulation
x A traffic control plan shall be prepared in accordance with City traffic control guidelines
specifically addressing construction traffic hauling excavated materials or operating within the
public right-of-way. The traffic control plan shall include signage and flagmen when necessary to
allow the heavy equipment to utilize residential streets and shall designate a haul route, if
applicable. The traffic control plan shall also include provisions for coordinating with local school
hours and emergency service providers regarding construction times.
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
Addendum C-2 January 2026
Table 3-6: Summary of Project Design Features/Methods, Agency Requirements, and Construction
Measures
Topic Project Design Features/Methods and Construction Practices
x For streets without specific traffic control measures recommended, a single lane of traffic
controlled by a flagger shall be maintained. During times when construction activity is not
occurring, these roadways shall be restored to their normal operating condition.
x Access to residences, businesses, and institutions shall be maintained at all times during
construction.
x Signs, notices, and other warning devices shall be posted to direct pedestrians to safe crossing
locations at intersections in advance of the construction zones.
x Wherever a bicycle lane is used for construction activity, a 14-foot travel lane shall be provided in
the same direction of travel.
x Projects located adjacent to I-5 shall be coordinated with Caltrans [the California Department of
Transportation] to identify conflicts or beneficial opportunities with Caltrans projects.
Air Quality x Water or dust control agents shall be applied to active grading areas, unpaved surfaces, and dirt
stockpiles as necessary to prevent or suppress particulate matter from becoming airborne. All soil
to be stockpiled over 30 days shall be protected with a secure tarp or tackifiers to prevent
windblown dust.
x Spoil or demolition material in each truckload shall be kept low enough to prevent spillage and
shall be sufficiently wetted down or covered with a secure tarp to prevent dust generation during
transport.
x Grading and other soil handling operations shall be suspended when wind gusts exceed 25 miles
per hour. The construction supervisor shall have a hand-held anemometer for evaluating wind
speed.
x Dirt and debris spilled onto paved surfaces at the project site and on the adjacent roadway shall
be swept or vacuumed and disposed of at the end of each workday to reduce resuspension of
particulate matter caused by vehicle movement.
x Vegetation disturbed by construction or maintenance activity shall be revegetated upon
completion of work in the area, where appropriate.
x Electrical power shall be provided from commercial power supply wherever feasible, to avoid or
minimize the use of engine-driven generators.
x Air filters on construction equipment engines shall be maintained in clean condition according to
manufacturers’ specifications.
x The construction contractor shall comply with the approved traffic control plan to reduce non-
project traffic congestion impacts. Methods to reduce construction interference with existing
traffic and the prevention of truck queuing around local sensitive receptors shall be incorporated
into this plan.
x Trucks and equipment shall not idle for more than 15 minutes when not in service.
x Best Management Practices (BMPs) shall be implemented at construction egress points to reduce
dirt tracking.
Noise x Heavy equipment shall be repaired at sites as far as practical from nearby residences and
occupied sensitive habitats.
x Construction equipment, including vehicles, generators, and compressors, shall be maintained in
proper operating condition and shall be equipped with manufacturers’ standard noise control
devices or better (e.g., mufflers, acoustical lagging, and/or engine enclosures).
x The City’s noise ordinance (Municipal Code Section 8.48.010) limits the hours of construction to
between 7 a.m. and sunset on weekdays and 8 a.m. to sunset on Saturdays. Construction is
prohibited on Sundays and holidays. The City Manager may grant an exception for night work
during the night, Sundays, and holidays if the construction is in a nonresidential zone and there
are no inhabited dwellings within 1,000 feet of the construction site.
x Electrical power shall be provided from commercial power supply, wherever feasible, to avoid or
minimize the use of engine-driven generators.
Project Name: Carlsbad Drainage Master Plan Update
CIP Project No. 6623
January 2026 C-3 Addendum
Table 3-6: Summary of Project Design Features/Methods, Agency Requirements, and Construction
Measures
Topic Project Design Features/Methods and Construction Practices
x Staging areas for construction equipment shall be located as far as practicable from residences
and sensitive habitats.
x Operating equipment shall be designed to comply with all applicable local, state, and federal
noise regulations.
x Noise attenuation walls/buffers shall be used to shield sensitive noise receptors from
construction-generated noise greater than 75 dBA within 50 feet of sensitive receptors.
x If lighted traffic control devices are to be located within 500 feet of residences, the devices shall
be powered by batteries, solar power, or similar sources, and not by an internal combustion
engine.
Geology/Soils x A site-specific geotechnical investigation shall be prepared to address geotechnical considerations
related to constructing and operating proposed 2008 DMP Update project components that
would involve excavation, grading, or construction of new structures. The report shall contain all
necessary requirements to address any adverse soils conditions that may be encountered in final
design of a facility. The project component shall be required to adhere to all such requirements.
The report shall include a discussion of site-specific geology, soils, and foundational issues; a
seismic hazards analysis to determine the potential for strong ground acceleration and ground
shaking; potential groundwater issues; and structural design recommendations. The soil engineer
and engineering geologist shall review the grading plans for adequate incorporation of
recommended measures prior to finalization.
x The project elements shall be designed and constructed in conformance to the Uniform Building
Code, current seismic design specifications of the Structural Engineering Association of California,
and other regulatory requirements.
x All construction shall be performed in accordance with the requirements of the City’s Grading
Ordinance (Municipal Code Title 15), which requires the control of erosion during construction
and the stabilization of all disturbed surfaces upon completion of construction.
Hydrology and
Water Quality
x The construction contractor, in consultation with the lead agency, shall be responsible for filing all
required notices with the Regional Water Quality Control Board (RWQCB), preparing the Storm
Water Pollution Prevention Plan (SWPPP) and/or Water Quality Technical Report (WQTR), and
implementing required BMPs. The construction manager shall be responsible for monitoring and
maintenance of BMPs until the construction area has been permanently stabilized to ensure that
they are working properly.
x BMPs shall include both erosion control measures (e.g., erosion blankets/mats) to prevent rainfall
from contacting exposed soil surfaces, and sediment control measures (e.g., gravel bags, silt
fences) to prevent eroded material from leaving construction areas, especially from flat graded
areas, in accordance with the required erosion control plan.
x Erosion and siltation into off-site areas during construction shall be minimized. The contractor
shall prepare an erosion control plan in accordance with applicable City code requirements. The
construction supervisor shall be responsible for ensuring that the erosion control plan is
developed and implemented.
x A construction spill contingency plan shall be prepared in accordance with County Department of
Environmental Health regulations and retained on-site by the construction manager. If soil is
contaminated by a spill, the soil shall be properly removed and transported to a legal disposal
site.
x If groundwater is encountered and dewatering is required, then the groundwater shall be
disposed of by pumping to the sanitary sewer system or discharging to the storm drain system
according to the conditions of the appropriate discharge permit.
x The lead agency shall consider using pervious or semi-pervious surfaces where possible to reduce
the increase in the velocity of peak flows.
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
Addendum C-4 January 2026
Table 3-6: Summary of Project Design Features/Methods, Agency Requirements, and Construction
Measures
Topic Project Design Features/Methods and Construction Practices
x For all potential impacts to natural drainages (i.e., predevelopment hydrology), BMPs onsite shall
be used to treat surface flows prior to their discharge to streams.
Biological
Resources
x The trimming of trees that could provide roost/nest sites for raptors shall only be completed
between September 16 and December 31 to prevent possible disruptions to breeding raptors.
x Any native vegetation removed shall be cut off at the surface, to allow maximum resprouting.
Areas where vegetation will be removed shall be revegetated with native species similar to those
removed.
x For projects within or adjacent to an HMP Hardline Preserve area, a worker education program
shall be implemented to ensure that all on-site personnel are fully informed of the biological
resources associated with the project. This program shall focus on (a) the purpose for resource
protection; (b) worker identification of sensitive resource areas in the field (e.g., areas delineated
on maps and by flags or fencing); (c) sensitive construction practices; (d) protocol to resolve
conflicts that may arise at any time during the construction process; and (e) ramifications of
noncompliance. This program shall be conducted by a qualified biologist and shall be a
requirement for all on-site personnel.
x For projects within or adjacent to an HMP Hardline Preserve area, a qualified project biologist
shall be made available for both the preconstruction and construction phases to review plans,
address protection of sensitive biological resources, and monitor ongoing work. The project
biologist shall review final plans, designate areas that need temporary fencing, and monitor the
installation of appropriate temporary fencing and construction. The project biologist shall monitor
construction activities within designated areas during critical times such as vegetation removal
and the installation of BMPs and HMP Hardline Preserve fencing, and ensure that all avoidance
and minimization measures are properly constructed and followed.
x Native vegetation disturbance shall be limited to the construction zones as indicated by flagging
or fencing. All vegetated areas outside of the project footprint shall be delineated as HMP
Hardline Preserve areas and depicted as such on design plans.
x Prior to the commencement of construction, the limits of grading shall be clearly delineated by a
survey crew prior to brushing, clearing, or grading. The limits, including clearly marked HMP
Hardline Preserve areas, shall be checked by a biological monitor before initiation of construction
grading. All fenced boundaries shall be maintained throughout the construction period. The
contractor(s) shall be responsible for mitigating impacts to sensitive biological resources beyond
those identified in this report or any subsequent reports that occur as a direct result of
construction activities.
x Temporary fencing shall be used in all locations of the project where proposed grading or clearing
would be within 100 feet of proposed biological open space. Fencing shall be placed on the
impact side and shall result in no vegetation loss within adjacent open space. All temporary
fencing shall be removed only after the conclusion of all grading, clearing, and construction.
x Activities shall be prohibited within drainages (other than those that may occur within an
approved construction zone), including staging areas, refueling areas, equipment access, and
disposal or temporary placement of excess fill.
x Appropriate BMPs shall be used to control dust, erosion, and sedimentation. No sediment or
debris shall be allowed to enter the creeks.
x The changing of oil, refueling, and other actions that could result in a release of a hazardous
substance shall be restricted to designated areas that are a minimum of 100 feet from any
sensitive plant populations, sensitive habitats, or drainages. Such designated areas shall be
surrounded with berms, sandbags, or other barriers to further prevent accidental spill of fuel, oil,
or chemicals. Any accidental spills shall be immediately contained, cleaned up, and properly
disposed. No equipment staging and refueling areas shall be located outside of existing staging
areas.
Project Name: Carlsbad Drainage Master Plan Update
CIP Project No. 6623
January 2026 C-5 Addendum
Table 3-6: Summary of Project Design Features/Methods, Agency Requirements, and Construction
Measures
Topic Project Design Features/Methods and Construction Practices
x All debris from bridge decks or columns shall be caught using tarps or other measures, so that
debris does not fall into the HMP Hardline Preserve areas or creeks.
x Appropriate postconstruction fencing and signage shall be installed to prohibit access and avoid
potential impacts to sensitive resources adjacent to project sites.
x Any night lighting needed for the 2008 DMP Update components shall be selectively placed,
shielded, and directed away from all HMP Hardline Preserve areas.
x Lighting shall be diverted away from any native habitat and shall consist of low-sodium or similar
lighting equipped with shields to focus light downward onto the appropriate subject.
x Unless authorized as part of construction, existing roads or disturbed areas shall be used to access
the project sites.
x Topsoil from the project sites shall be stockpiled within the construction sites where feasible. If
topsoil from construction must be stockpiled off-site, it shall be stockpiled in disturbed areas.
Stockpile areas shall be delineated on the grading plans and reviewed by a qualified biologist.
x On-site staging areas shall be used where feasible. Staging areas shall be delineated on the
grading plans and reviewed by a qualified biologist. If staging areas outside the construction
footprint are used, then they shall be surveyed for biological resources prior to their use.
x Native plants shall be used to the greatest extent feasible in the landscape areas adjacent to
mitigation or open space areas (including wetland and riparian areas), which shall be determined
during project level review of applicable project components of the 2008 DMP Update. The lead
agency shall not plant, seed, or otherwise introduce invasive exotic plant species to the
landscaped areas adjacent to and/or near the mitigation/open space area or wetland and riparian
areas. Exotic plant species not to be used include those species on Lists A and B of the California
Invasive Plant Council’s (Cal-IPC) Invasive Plant Inventory. These include such species as pepper
trees, pampas grass, fountain grass, ice plant, myoporum, black locust, and capeweed. Areas
hydroseeded for temporary erosion control shall use native plant species.
x Project design, construction, use, and maintenance shall comply with the HMP “Management and
Monitoring Actions,” as appropriate, found in subsection 2 of HMP Section F, Preserve
Management.
x Project design, construction, use, and maintenance shall comply with the HMP “Adjacency
Standards,” as appropriate, found in subsection 3 of HMP Section F, Preserve Management.
Public Safety x A “safe construction practices” plan shall be prepared and implemented in accordance with
California Occupational Safety and Health Administration requirements for worker and public
safety during installation of pipelines and other applicable facilities.
MITIGATION MEASURES
Noise Mitigation Measures, Program Level (Section 4.6.5.1, EIR pages 4.6-14 to 4.6-15)
NOTE: REFER TO ADDENDUM SECTION 3.8.5 FOR REVISIONS TO MITIGATION MEASURE NOISE-1.
The following mitigation measures shall be applicable to 2008 DMP Update components that shall result
in potentially significant noise impacts (Mitigation Measures Noise-1 and/or Noise-2) during
construction activities. Implementation of these mitigation measures will reduce impacts to a less than
significant level.
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
Addendum C-6 January 2026
Noise-1 If a proposed project component would require the use of construction equipment that may
generate noise of 75 dBA or greater within 50 feet1 of a sensitive receptor for a period of
longer than 3 days, or would require work to be done between sunset and 7:00 a.m., as
permitted by Municipal Code Section 8.48.020, preparation and implementation of a project
level noise evaluation shall be required. The evaluation shall assess potential noise levels
and require the implementation of appropriate noise attenuation measures to reduce
potential noise impacts to less than 75 dBA Leq during the daytime or to 60 dBA Leq at
nighttime. The noise evaluation shall consider the use of temporary noise walls, noise
blankets, noise-reducing enclosures for individual pieces of equipment, and engines with
special mufflers as potential noise attenuation measures. Monitoring shall be required to
demonstrate the effectiveness of the project-specific measures to reduce noise levels to this
limit. If monitoring results indicate that the measures are not reducing noise to acceptable
levels, work will cease until further environmental analysis is performed that recommends
additional noise attenuation measures. For emergency projects as defined in Municipal
Code Section 8.48.020(A), the requirement for evaluation, monitoring, and potential
additional mitigation measures shall be performed if determined feasible by the City
Engineer.
Noise-2 If a proposed project component would require the use of pile drivers, preparation and
implementation of a project level vibration evaluation shall be required. The evaluation shall
consider the potential vibration levels associated with project construction at the nearest
structure locations. The analysis shall demonstrate that vibration levels at those structures
remain below 0.2 in/sec, or a different construction technique resulting in vibration less
than 0.2 in/sec shall be required.
Biological Resources Mitigation Measures, Program Level (Section 4.10.5.1, EIR pages 4.10-69 to
4.10-76)
Implementation of the Mitigation Measures Bio 1-a through Bio 1-d would be required for DMP
components that would impact sensitive HMP habitats and would reduce direct and cumulative impacts
to below a level of significance. Note that the descriptions of Type A through F habitats are per Table 11
of the HMP. Avoidance and on-site mitigation are the priority. Future project level environmental review
for 2008 DMP Update components that would impact biological resources would be provided to the
Wildlife Agencies for review to verify consistency with the City’s HMP.
Bio-1a For impacts to Type A habitats (coastal salt marsh, alkali marsh, freshwater marsh,
estuarine, salt pan/mudflats, riparian forest, riparian woodland, riparian scrub, disturbed
wetlands, flood channel, fresh water, Engelmann oak woodland, coast live oak woodland) a
goal of no net loss of habitat value or function shall be met. Habitat replacement ratios and
the specific location of mitigation lands shall be determined in consultation with the USFWS
[United States Fish and Wildlife Service], USACE [United States Army Corps of Engineers],
and CDFG [California Department of Fish and Game]as appropriate in accordance with the
requirements of the federal CWA [Clean Water Act], federal wetland policies, and the
California Fish and Game Code. All mitigation lands for impacts to riparian and wetland
1 Mitigation Measure Noise-1 is revised in the Addendum to change “90 feet” to “50 feet.”
Project Name: Carlsbad Drainage Master Plan Update
CIP Project No. 6623
January 2026 C-7 Addendum
habitats shall be in the City or MHCP [Multiple Habitat Conservation Program] plan area, at
a ratio to be determined by the applicable resource agencies at the time of project
permitting.
Bio-1b Impacts to Type B habitats (beach, southern coastal bluff scrub, maritime succulent scrub,
southern maritime chaparral, native grass) shall be mitigated at a 3:1 ratio, or at an
appropriate ratio based on habitat quality and quantity as determined in coordination with
the applicable resource agencies at the time of project permitting.
Bio-1c Impacts to Type C habitats (California gnatcatcher-occupied coastal sage scrub) shall be
mitigated at a 2:1 ratio, or at an appropriate ratio based on habitat quality and quantity as
determined in coordination with the applicable resource agencies at the time of project
permitting.
Bio-1d Impacts to Type D (unoccupied coastal sage scrub, coastal sage/chaparral mix, chaparral),
Type E (annual, nonnative grassland), and Type F (disturbed lands, eucalyptus, agricultural
lands) habitats are not subject to the fee payment. Instead, these types of impacts will be
mitigated at the Lake Calavera Mitigation Parcel,2 per the ratios included in HMP Table 11.
An appropriate mitigation ratio would be determined based on habitat quality and quantity
as determined in coordination with the applicable resource agencies at the time of project
permitting.
Implementation of Mitigation Measures Bio-1e through Bio-1g shall be required for DMP components
that would result in indirect impacts to coastal California gnatcatcher, within 150 meters (500 feet) of
the proposed project footprint, from construction-generated noise and would reduce impacts to below
a level of significance:
Bio-1e Prior to the first preconstruction meeting for each project component, the City shall verify
that the following statement is included in the construction specifications: No clearing,
grubbing, grading, or other construction activities within occupied gnatcatcher habitat shall
occur between March 1 and August 15, the breeding season of the gnatcatcher. No clearing,
grubbing, grading, or other construction activities within or adjacent to unoccupied habitat
shall occur between March 1 and August 15, until the requirements in Bio-1f and Bio-1g)
have been met to the satisfaction of the City.
Bio-1f A qualified Biologist (possessing a valid Endangered Species Act Section 10(a)(1)(a) Recovery
Permit) shall survey appropriate habitat areas subject to construction noise levels exceeding
60 dBA Leq for the presence of gnatcatcher. Gnatcatcher surveys shall be conducted a
minimum of 4 weeks (within the breeding season) prior to commencement of construction.
If gnatcatchers are present, then the following conditions must be met:
• Between March 1 and August 15, no construction activities shall occur within any
portion of the site where such activities would result in noise levels exceeding 60 dBA
Leq at the edge of occupied gnatcatcher habitat. An analysis concluding that
construction-generated noise would not exceed 60 dBA Leq at the edge of occupied
2 The text of Mitigation Measure 1d was amended per City Council Agenda Bill #19,540, August 5, 2008. Specifically, “Lake
Calavera Mitigation Bank” was changed to “Lake Calavera Mitigation Parcel.”
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
Addendum C-8 January 2026
habitat must be completed by a qualified Acoustician (possessing current noise engineer
license or registration, with experience monitoring noise levels for listed wildlife species)
and approved by the City at least 2 weeks prior to commencement of construction
activities; OR
• At least 2 weeks prior to commencement of construction activities, and under the
direction of a qualified Acoustician, noise attenuation measures (e.g., berms, walls) shall
be implemented to ensure that construction-generated noise will not exceed 60 dBA Leq
at the edge of occupied gnatcatcher habitat. Concurrent with commencement of
construction activities and with implementation of necessary noise attenuation
measures, noise monitoring3 shall be conducted at the edge of occupied habitat to
ensure that construction-generated noise does not exceed 60 dBA Leq. If the noise
attenuation measures implemented are determined to be inadequate by the qualified
Acoustician or Biologist, then the associated construction activities shall cease until such
time that adequate noise attenuation is achieved or until the end of the breeding
season (August 15).
Bio-1g If gnatcatchers are not detected during the preconstruction survey within areas that would
be subject to construction noise levels exceeding 60 dBA Leq, the qualified Biologist shall
submit substantial evidence to the City and applicable regulatory agencies demonstrating
whether noise attenuation measures (e.g., berms, walls) are necessary between March 1
and August 15 as follows:
• If this evidence indicates the potential is high for gnatcatcher to be present based on
historical records or site conditions, then measure Bio-1f shall be adhered to as
specified above.
• If this evidence concludes that no impacts to this species are anticipated, no mitigation
measures will be necessary.
Implementation of Mitigation Measures Bio-1h through Bio-1j shall be required for DMP components
that result in indirect impacts to the least Bell’s vireo, within 150 meters (500 feet) of the proposed
project footprint, from construction-generated noise and would reduce impacts to below a level of
significance:
Bio-1h Prior to the first preconstruction meeting for each project component, the City shall verify
that the following statement is included in the construction specifications: No clearing,
grubbing, grading, or other construction activities shall occur between March 15 and
September 15 (least Bell’s vireo breeding season) in occupied least Bell’s vireo habitat. No
clearing, grubbing, grading, or other construction activities within or adjacent to unoccupied
3 Noise monitoring shall continue at least twice weekly on varying days, or more frequently depending on the construction
activity, to verify that noise levels at the edge of occupied habitat are maintained below 60 dBA Leq or to the ambient noise
level if it already exceeds 60 dBA Leq. If not, other measures shall be implemented in consultation with the Biologist and
the City, as necessary, to reduce construction-generated noise levels to below 60 dBA Leq or to the ambient noise level if it
already exceeds 60 dBA Leq. Such measures may include, but are not limited to, limitations on the placement of
construction equipment and the simultaneous use of equipment.
Project Name: Carlsbad Drainage Master Plan Update
CIP Project No. 6623
January 2026 C-9 Addendum
least Bell’s vireo habitat shall occur between March 15 and September 15 until the
requirements in Bio-1i and Bio-1j have been met to the satisfaction of the City.
Bio-1i A qualified Biologist shall survey those wetland areas that would be subject to construction
noise levels exceeding 60 dBA Leq for the presence of least Bell’s vireo. Least Bell’s vireo
surveys shall be conducted a minimum of 8 weeks (within the breeding season) prior to
commencement of construction. If least Bell’s vireos are present, then the following
conditions must be met:
• Between March 15 and September 15, no construction activities shall occur within any
portion of the site where such activities would result in noise levels exceeding 60 dBA
Leq at the edge of occupied least Bell’s vireo habitat. An analysis showing that
construction-generated noise would not exceed 60 dBA Leq at the edge of occupied
habitat must be completed by a qualified Acoustician (possessing current noise engineer
license or registration), with experience monitoring noise levels for listed wildlife
species) and approved by the City at least 2 weeks prior to commencement of
construction activities; OR
• At least 2 weeks prior to commencement of construction activities, and under the
direction of a qualified Acoustician, noise attenuation measures (e.g., berms, walls) shall
be implemented to ensure that construction-generated noise would not exceed 60 dBA
Leq at the edge of occupied least Bell’s vireo habitat. Concurrent with commencement of
construction activities and with implementation of necessary noise attenuation
measures, noise monitoring shall be conducted at the edge of occupied habitat to
ensure that construction-generated noise does not exceed 60 dBA Leq. If the noise
attenuation measures implemented are determined to be inadequate by the qualified
Acoustician or Biologist, then the associated construction activities shall cease until such
time that adequate noise attenuation is achieved or until the end of the breeding
season (September 16).
Bio-1j If least Bell’s vireos are not detected during the preconstruction survey within areas of
potential habitat that would be subject to construction noise levels exceeding 60 dBA Leq,
the qualified Biologist shall provide evidence to the City and applicable regulatory agencies
demonstrating whether noise attenuation measures (e.g., berms, walls) are necessary
between March 15 and September 15 as follows:
• If this evidence indicates the potential is high for least Bell’s vireo to be present based
on historical records or site conditions, then condition 1i shall be adhered to as specified
above.
• If this evidence concludes that no impacts to this species are anticipated, no mitigation
measures would be necessary.
Implementation of Mitigation Measures Bio-1k through Bio-1m shall be required for DMP components
that would result in indirect impacts to the southwestern willow flycatcher, within 150 meters (500 feet)
of the proposed project footprint, from construction-generated noise and would reduce impacts to
below a level of significance:
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CIP Project No. 6623
Addendum C-10 January 2026
Bio-1k Prior to the first preconstruction meeting for each phase of the project component, the City
shall verify that the following statement is included in the construction specifications: No
clearing, grubbing, grading, or other construction activities shall occur within occupied
southwestern willow flycatcher habitat between May 1 and September 1 (southwestern
willow flycatcher breeding season)). No clearing, grubbing, grading, or other construction
activities within or adjacent to unoccupied southwestern willow flycatcher habitat shall
occur between May 1 and September 1 until the requirements in Bio-1l and Bio-1m have
been met to the satisfaction of the City.
Bio-1l A qualified Biologist shall survey those wetland areas that would be subject to construction
noise levels exceeding 60 dBA Leq for the presence of southwestern willow flycatcher.
Southwestern willow flycatcher surveys shall be conducted a minimum of 6 weeks (within
the breeding season) prior to commencement of construction. If southwestern willow
flycatchers are present, then the following conditions must be met:
• Between May 1 and September 1, no construction activities shall occur within any
portion of the site where such activities would result in noise levels exceeding 60 dBA
Leq at the edge of occupied southwestern willow flycatcher habitat. An analysis showing
that construction-generated noise would not exceed 60 dBA Leq at the edge of occupied
habitat must be completed by a qualified Acoustician (possessing current noise engineer
license or registration, with experience monitoring noise levels for listed wildlife species)
and approved by the City at least 2 weeks prior to commencement of construction
activities; OR
• At least 2 weeks prior to commencement of construction activities, and under the
direction of a qualified Acoustician, noise attenuation measures (e.g., berms, walls) shall
be implemented to ensure that construction-generated noise would not exceed 60 dBA
Leq at the edge of occupied southwestern willow flycatcher habitat. Concurrent with
commencement of construction activities and with implementation of necessary noise
attenuation measures, noise monitoring shall be conducted at the edge of occupied
habitat to ensure that construction-generated noise does not exceed 60 dBA Leq. If the
noise attenuation measures implemented are determined to be inadequate by the
qualified Acoustician or Biologist, then the associated construction activities shall cease
until such time that adequate noise attenuation is achieved or until the end of the
breeding season (September 2).
Bio-1m If southwestern willow flycatchers are not detected during the preconstruction survey
within areas of potential habitat that would be subject to construction noise levels
exceeding 60 dBA Leq, the qualified Biologist shall submit substantial evidence to the City
and applicable regulatory agencies demonstrating whether noise attenuation measures
(e.g., berms, walls) are necessary between May 1 and September 1 as follows:
• If this evidence indicates the potential is high for southwestern willow flycatcher to be
present based on historical records or site conditions, then measure Bio-1l shall be
adhered to as specified above.
• If this evidence concludes that no impacts to this species are anticipated, no mitigation
measures would be necessary.
Project Name: Carlsbad Drainage Master Plan Update
CIP Project No. 6623
January 2026 C-11 Addendum
Bio-1n To identify the presence/absence of sensitive and/or native fish species within potential
aquatic habitat (e.g., freshwater species such as the tidewater goby), the following
measures shall be implemented:
• Conduct a trapping/netting study; if sensitive native fish are detected, then
(1) trapping and translocation of the sensitive fish shall occur, and/or
(2) exclusionary trapping shall be placed to prevent sensitive fish species from entering
the area of disturbance during in-stream activity.
Bio-1o Where required, protocol-level surveys will be conducted for sensitive plant or wildlife
species prior to construction of 2008 DMP Update components, as determined by the
Wildlife Agencies.
Bio-2a For DMP components that would result in the loss of sensitive habitats within the Coastal
Zone, mitigation shall be required at ratios consistent with requirements of the HMP,
including Standards 7-1 through 7-14 of Section D, and the policies and provisions of the
LCP.
Bio-2b Mitigation ratios shall be consistent with the provisions of the HMP and LCP. For all projects
affecting riparian and wetland habitat, habitat replacement ratios and the specific location
of mitigation lands shall be determined in consultation with the USFWS, USACE, and CDFG
as appropriate in accordance with the requirements of the federal CWA, federal wetland
policies, and the California Fish and Game Code. For 2008 DMP Update components with
unavoidable impacts, the City shall demonstrate that viable wetlands can either be: 1)
created at a minimum ration of 1:1 within close proximity of the impact area to replace the
wildlife function affected by the project,; or, 2) provide proof that wetland creation credits
at a minimum ratio of 1:1 have been purchased at a Wildlife Agency approved bank.
Consistent with the City’s HMP, higher ratios will be required for impacts to high quality
wetlands (e.g., occupied by listed or otherwise sensitive species) and for wetlands within the
Coastal Zone. For 2008 DMP Update components where wetland creation will be necessary,
construction shall not be initiated until a viable wetland creation mitigation site with long-
term value is identified (and if necessary purchased by the City) and the wetland mitigation
plan is approved by the appropriate Resource Agencies. The wetland creation shall not
require impacts to sensitive wildlife or vegetation communities. All mitigation lands for
impacts to riparian and wetland habitats shall be in the City or MHCP plan area as deemed
appropriate by the Wildlife Agencies.
Bio-3 As needed, surveys for state and federally listed sensitive plant species shall be conducted
to complete a determination of suitable habitat presence prior to implementation of 2008
DMP Update components. Surveys shall be conducted at a time when sensitive plant species
would be most observable.
Bio-4 At the project design stage for the 2008 DMP Update components located within key Core
Areas and linkages, design measures and restoration efforts shall be required to maintain
the viability of the wildlife corridors throughout Carlsbad.
Carlsbad Drainage Master Plan Update
CIP Project No. 6623
Addendum C-12 January 2026
Cultural Resources Mitigation Measures, Program Level (Section 4.11.5.1, EIR pages 4.11-12 to
4.11-15)
Cult-1 The following mitigation measures will be required if a proposed PLDA or non-PLDA
component is located in an undeveloped area that could potentially impact significant
cultural deposits, as indicated in Tables 4.11-2 and 4.11-3. In addition, for any operation and
maintenance activities that will require temporary construction of an access road through
previously undeveloped or undisturbed areas, the following mitigation measures will be
required prior to construction.
a) Preconstruction Requirements – Prior to the start of construction, a pedestrian survey
shall be conducted under the supervision of a qualified archaeologist for previously
undisturbed areas that have not been surveyed or adequately surveyed (e.g., the area
was surveyed with outdated or non protocol methods). The survey shall be conducted in
parallel linear transects spaced no farther than 10 meters apart in undeveloped areas.
1) Cultural resources, if found during the survey, shall be photographed, mapped using
a global positioning system (GPS), and recorded on the appropriate California
Department of Parks and Recreation forms (DPR Form 523A/B). The forms shall be
submitted to the SCIC for the assignment of Primary numbers within 1 week of the
survey.
2) Within 1 month of completion of the field survey, a draft letter report or technical
report shall be submitted to the City for review, whether the survey is negative or
positive. A final report shall be submitted within 6 weeks of receipt of the City’s
comments, with a copy submitted to the SCIC for their files.
b) If the pedestrian survey is positive, the qualified archaeologist shall conduct an updated
archival search, if needed, as well as additional detailed field testing. Local Native
American groups shall be contacted for testing of prehistoric cultural resources
regarding the project. Where applicable, the City will execute a Pre-Excavation
Agreement with the appropriate Native American groups.
1) Prior to the start of field testing, surface artifacts and/or features shall be marked
and mapped using a GPS. Testing shall be required if surface artifacts are
discovered, and shall include a program of 30-cm diameter shovel test pits (STPs) to
define site boundaries and identify the potential for a substantial subsurface
deposit.
2) Based on the results of the STPs, additional measures such as Test Excavation Units
or mechanical trenching (for substantial historic sites) would be placed in areas with
the potential for a substantial subsurface deposit, as determined by the qualified
archeologist.
3) All excavated soils shall be screened through Я-inch mesh hardware cloth. On
completion of the project the artifact collection, along with copies of the catalogs
and the technical report, shall be permanently curated at the San Diego
Archaeological Center. An updated site record shall be prepared and submitted to
the SCIC.
Project Name: Carlsbad Drainage Master Plan Update
CIP Project No. 6623
January 2026 C-13 Addendum
4) Within 3 months of completion of the fieldwork, a draft technical report including
evaluations and recommendations shall be prepared and submitted. The final
technical report shall be submitted within 6 weeks of receipt of the City’s
comments.
Cult-2 Monitoring Requirements – Construction monitoring will be required for proposed PLDA or
non-PLDA DMP components that involve excavation or grading within undisturbed native
soils and could potentially impact subsurface cultural deposits, as indicated in Tables 4.11-2
and 4.11-3.
a) Prior to the first preconstruction meeting for the project, the Planning Director (PD)
shall verify that the requirements for archaeological monitoring and Native American
monitoring, if applicable, have been noted on the appropriate construction documents.
The applicant shall retain a qualified archaeologist to verify that a records search has
been completed and updated, as necessary, and to implement the monitoring program.
At the preconstruction meeting, the archaeologist shall submit to the PD a copy of the
site/grading plan that identifies areas to be monitored.
b) The qualified archaeologist shall be present full-time during grading/excavation of
native soils with the potential to contain buried cultural features or deposits and shall
document activity via the Consultant Monitor Record. Monitoring of trenches shall
include mainline, laterals, services and all other appurtenances that impact native soils 1
foot deeper than existing as detailed on the plans or in the contract documents. It is the
construction manager’s responsibility to keep the archaeological monitors up-to-date
with current plans.
c) In the event of a discovery, the archaeologist, or the Principal Investigator (PI) if the
monitor is not qualified as a PI, shall divert, direct, or temporarily halt ground-disturbing
activities in the area of the discovery to allow for preliminary evaluation of potentially
significant archaeological resources. The PI shall also immediately notify the
construction manager and the PD of such findings at the time of discovery.
1) The significance of the discovered resources shall be assessed by the PI. For
significant archaeological resources, a Research Design and Data Recovery Program
shall be prepared and implemented by the qualified archaeologist. The results of the
Research Design and Data Recovery Program shall be approved by the City before
ground-disturbing activities in the area of discovery shall be allowed to resume.
d) If human remains are discovered, work shall halt in that area and procedures set forth in
the California Public Resources Code (Sec. 5097.98) and State Health and Safety Code
(Sec. 7050.5) shall be implemented. Construction in that area shall not resume until the
remains have been evaluated and conveyed to appropriate descendants or reinterred to
the satisfaction of the PI.
e) The archaeologist shall notify the PD, in writing, of the end date of monitoring. The
archaeologist shall be responsible for ensuring that all cultural remains collected are
cleaned, catalogued, and permanently curated with an appropriate institution; that a
letter of acceptance from the curation institution has been submitted to the Planning
Department; that all artifacts are analyzed to identify function and chronology as they
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CIP Project No. 6623
Addendum C-14 January 2026
relate to the history of the area; that faunal material is identified as to species; and that
specialty studies are completed, as appropriate.
f) Within 3 months following the completion of monitoring, the Draft Results Report (even
if negative) and/or evaluation report, if applicable, which describes the results, analysis,
and conclusions of the Archaeological Monitoring Program (with appropriate graphics)
shall be submitted to the PD for approval. For significant archaeological resources
encountered during monitoring, the Research Design and Data Recovery Program shall
be included as part of the Draft Results Report. The qualified archaeologist shall be
responsible for recording (on the appropriate State of California Department of Park and
Recreation forms-DPR 523 A/B) any significant or potentially significant resources
encountered during the Archaeological Monitoring Program, and submitting such forms
to the SCIC with the Final Results Report.
Paleontological Resources Mitigation Measures, Program Level (Section 4.12.5.1, EIR pages 4.12-6
to 4.12.7)
Paleo-1 A monitoring program shall be prepared and implemented if excavation into intact geologic
formations with moderate to high sensitivity is proposed. Components of such a monitoring
program shall include, but not be limited to, the following:
a) A qualified paleontological monitor shall be present at a pregrading meeting with the
construction contractor and PD of the City Planning Department. The purpose of the
meeting will be to consult and coordinate the role of the paleontologist during
construction. The paleontological monitor shall have adequate knowledge and
experience with fossilized remains likely to be present to identify them in the field. The
paleontological monitor shall be adequately experienced to remove paleontological
resources for further study.
b) The paleontological monitor shall be present during the applicable stages of grading and
construction (including trenching), as determined at the pregrading meeting. The
paleontological monitor shall have the authority to temporarily direct, divert, or halt
grading in the area of an exposed fossil to facilitate evaluation and, if necessary, salvage.
At the discretion of the monitor, recovery may include washing and picking of soil
samples for microvertebrate bone and teeth. Construction activities in the area of
discovery shall resume upon notification by the paleontologist that fossil remains have
been recovered. The City shall ensure the contractor is aware of the random nature of
fossil occurrences and the possibility of a discovery of such scientific and/or educational
importance that it might warrant a long-term salvage operation or preservation. All
fossils collected shall be donated to a museum with a systematic paleontological
collection, such as the San Diego Natural History Museum. The City shall ensure the
grading contractor is aware of this provision. Conflicts regarding the role and authority
of the monitor shall be resolved by the PD or his/her designee.
c) Collected fossils shall be cleaned and/or prepared to a point of identification, and then
curated to museum standards (cataloging of locality and specimen data, numbering,
identification, labeling) before being deposited in an appropriate public facility (or
facilities) that can provide permanent archival storage (so that specimens are available
Project Name: Carlsbad Drainage Master Plan Update
CIP Project No. 6623
January 2026 C-15 Addendum
for future scientific study). A report detailing the mitigation and any discoveries shall be
prepared and submitted to the City within 3 months following termination of the
paleontological monitoring program, even if negative. The report shall include necessary
maps, graphics, and fossil lists to adequately document the paleontological monitoring
program.