HomeMy WebLinkAbout3184; CANNON ROAD WEST; CONCEPTUAL WETLANDS MITIGATION PLAN; 1997-01-01 (2)Conceptual Wetlands Mitigation Plan
for. Reaches 1 ánd.2 Of the .
Cannon Road Extension Project
January 1997 . . .., .
Conceptual Mitigation Plan for Reaches 1 and 2
TABLE OF CONTENTS
1.0 INTRODUCTION ................................................1
1.1 PROJECT DESCRIPTION ....................................1
1.1.1 Location of the Project ................................1
1.1.2. Overall Project Summary .................................4
1.1.3 Responsible Parties' ..................................5
1.1.4 Jurisidictional Areas to be Filled by Habitat Type ..............5
1.1.5 Types, Functions, and Values of the Jurisdictional Areas to be
Directly or Indirectly Impacted ...............................6
2.0 ' GOAL OF MITIGATION ..........................................10
2.1 TYPE OF HABITAT TO BE CREATED/ENHANCED .............10
2.2 FUNCTIONS AND VALUES OF HABITAT TO BE CREATED ........10
2.3 TIME LAPSE ...........................................10
2.4 ESTIMATED COST ......................................10
3.0 FINAL SUCCESS CRITERIA ...................................10
3.1 TARGET FUNCTIONS AND VALUES ...........................12
3.2 TARGET HYDROLOGICAL REGIME .........................12
3.3 TARGET JURISDICTIONAL ACREAGE TO BE CREATED/•
ENHANCED ..............................................15
4.0 THE PROPOSED MITIGATION SITE ................................ 15
4.1 LOCATION OF THE MITIGATION AREA ................... '. 15 4.2 OWNERSHIP STATUS ..................................17
4.3 EXISTING FUNCTIONSAND VALUES OF THE MITIGATION AREA. 17
4.4 PRESENT AND PROPOSED USES OF THE MITIGATION AREA.'.... 17
4.5 ZONING .........
............18
5.0 IMPLEMENTATION PLAN .....................................18
5.1 ' RATIONALE FOR EXPECTING IMPLEMENTATION SUCCESS .....18
5.2 . RESPONSIBLE PARTIES ..................................... 20
5.3 SCHEDULE* .......................
.
.. ..................20
5.4 SITE PREPARATION ........................................20
5.5 PLANTING PLAN ........................................21
5.6 IRRIGATION PLAN ........................................25
5.7. AS-BUILT CONDITIONS . •
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Cannon' Road Extensitrn Project
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City of Carlsbad, California
Conceptual Mitigation Plan for Reaches 1 and 2
0 6.0 MAINTENANCE DURING MONITORING PERIOD ....................26
6.1 REPLACEMENT OF DEAD OR DISEASED PLANT MATERIAL .....26
6.2 WEED CONTROL ....................................... 26
6.3 PRUNING AND STAKING ................................27
6.4 EROSION CONTROL ......................................27
6.5 SITE ACCESS .........................................27
6.6 COWBIRD TRAPPING ....................................28
7.0 MONITORING PROGRAM ......................................28
7.1 HORTICULTURAL MONITORING ...........................28
7.2 BOTANICAL MONITORING ..............................29
7.3 REPORTING ...........................................29
8.0 COMPLETION OF MITIGATION ..................................30
8.1 NOTIFICATION OF COMPLETION .............................30
8.2 CORPS CONFIRMATION ....................................30
9.0 CONTINGENCY MEASURES ....................................30
9.1 INITIATING PROCEDURES 0 30 9.2 ALTERNATIVE LOCATIONS FOR CONTINGENCY MITIGATION ... 30
9.3 FUNDING MECHANISMS .................................31
9.4 RESPONSIBLE PARTIES :................................31
10.0 REFERENCES ..............................................31
W Cannon Road Extension Project City of Carlsbad, California
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Conceptual Mitigation Plan for Reaches 1 and 2
S , List of Figures
Figure 1 Regional Map ............................................2
' Figure 2 Vicinity Map ............................................3
Figure 3 Proposed Mitigation Site, Macario Canyon 16
Figure 4 , Riparian Planting Design ...................................23
Figure 5 Conceptual Marsh Planting Design .............................24
Plate 1 Proposed Mitigation Sites, Macario Canyon (west view) ..........Pocket
List ofTables • ' '. •
Table 3.1 Project Success Standards and Measures to be Taken if theStandard is
NotMet ...............................................•11
Table 3.2 Plant Species Recommended for Cannon Road-Reaches 'l and 2 Willow
Scrub Revegetation Site at Macario Canyon, Carlsbad 13
Table 3.3 •' Plant Species Recommended for Cannon Road-Reaches 1 and 2 Marsh
Revegetation Site at Macario Canyon, Carlsbad ..................'. .' . . 14
Table 5.1 Soil Salinity Test Results 19
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S Cannon Road Extension Project. '• •. • City of Carlsbad, California
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Conceptual Mitigation Plan for Reaches 1 and 2 - S
1.0 1I4TRODUCTION
This conceptual mitigation plan identifies measures to offset impacts to wetland and riparian
resources that would result from the construction of Cannon Road Reaches 1 and 2. The project
site and proposed mitigation area are located in the City of Carlsbad in San Diego County,
California (Figure 1). This plan will be utilized to address the conceptual design with the resource
agencies, and to assist and guide future designers in final plan implementation.
The mitigation measures described herein are designed to fulfill the requirements of existing
project permits including:
U. S. Army Corps of Engineers (ACOE) Permit Number 92-194 EW;
U. S. Fish and Wildlife Service (USFWS) Biological Opinion 1-6-92-F-34
(07 April 1992);
U California Department of Fish and Game (CDFG) Streambed Alteration Agreement
Notification No. 5-273-89; and
I California Coastal Commission (CCC) Permit No. 6-89-195.
Affected waters and wetlands occur in and adjacent to an unnamed water course in Macario
Canyon and Agua Hedionda Creek. These streams flow into the Agua Hedionda Lagoon within
one-half mile of the affected areas. The proposed mitigation site is located in Macario Canyon.
This plan is designed to satisfy the requirements of the CDFG, USFWS, ACOE, and CCC.
Impacts (both temporary and permanent) to native habitat due to bridge construction would be
mitigated at a 1:1 ratio for all wetland impacts. This ratio is a guideline set by the ACOE for
mitigation prior to impact. Concurrence of both the CDFG and the CCC must be' obtained if this
ratio is used to mitigate project related impacts. These agencies have verbally indicated that the
1:1 mitigation ratio would be acceptable if accomplished prior to construction..
1.1 PROJECT DESCRIPTION
1.1.1 Location of the Project
Reach 1 of Cannon load would be located south of Agua Hedionda Lagoon between 1-5 on the
west and the proposed route of Faraday Avenue east of Macario Canyon (Figures 1 and 2). From
its. interchange with 1-5, existing Cannon Road runs east about 1,000 feet ending at Car Country
Drive,
S Cannon Road Extension Project
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S City of Carlsbad, California
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Conceptual Mitigation Plan for Reaches 1 and 2
0 1.1.2 Overall Project Summary
The proposed Reach 1 of Cannon Road would extend from Car Country Drive onto the' mesa
above Agua Hëdionda Lagoon and traverse Macario Canyon near its confluence with the lagoon
basin. Reach 1 of Cannon Road is proposed to cross Macario Canyon on a bridge and terminate
on the eastern canyon rim. Reach 1 was the subject of an EIR certified on June 27, 1989.
Permits from resource agencies were obtained and are listed in Section 1.0, Introduction.
The proposed Reach 2 of Cannon Road begins on the eastern edge of Macario Canyon and travels
northeasterly to the intersection with El Camino Real. The project area is bounded by El Camino
Real to the north, College Avenue to the east, and Palomar Airport Road to the south (Figure 2).
Reach 2 of Cannon Road was originally analyzed under the development proposal of the Kelly
Ranch Environmental Impact Report (Em) Permits from the resource agencies were obtained
for that project in the middle to late 1980s and have since expired or are in suspense.
Portions of the Kelly Ranch project were constructed, including grading for the alignment of
Cannon Road Reach 2. The width of the proposed Cannon Road Reach 2 was cleared, graded,
and all improvements for drainages, including desiltation basins, were completed. Within the
Cannon Road right-of-way, a surcharge and a temporary berm were placed on top of the intended
future road. The current proposed project would finish the intended grading (which would include
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the removal of the surcharge and the berm), resulting in the ultimate construction of the road.
The Cannon Road Reach 2 project will generally be constructed according to the original grading
and design plans with two exceptions. A slight modification has been made in the turn radius and
the bridge would be 10 feet wider than originally planned.
This plan mitigates impacts from the current Reach 2 project. Impacts associated with the Kelly
Ranch project have been mitigated.
The proposed intersection alignment is at the eastern end of the project site and would connect
Cannon Road to El Camino Real. This requires the construction of a bridge over Agua Hedionda
Creek, and is the preferred alignment as shown on the original grading plans.
The entire length of the proposed Cannon Road is within the City of Carlsbad. Cannon Road is
included in the Carlsbad General Plan Circulation Element as a four-lane major arterial. The site
is also in the portion of the California Coastal Zone in the Agua Hedonda Land Use Plan,
adopted in 1982 as part of the City of Carlsbad Local Coastal Program.
is Cannon Road Extension Project City of Carlsbad, California
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Conceptual Mitigation Plan for Reaches 1 and 2
1.1.3 Responsible Parties
Applicant: City of Carlsbad
Address: 2075 Las Palmas Drive
Carlsbad, California 92009-1576
Contact: Ms. Sherri Howard, Associate Engineer
Preparer: Tetra Tech, Inc.
Address: 591 Camino de la Reina, Suite 640
San Diego, California 92108
1.1.4 Jurisdictional Areas to be Directly Impacted by Habitat Type
The following jurisdictional areas would be directly impacted by the Cannon Road project:
Southern willow scrub • •
Reach 1 • 2.48 acres •
Reach 2 0.16 acre
• Brackish marsh • •
Reach 1 0.10 acre
N Disturbed riparian scrub
Reach 2 0.13 acre
• Open water • • S •
•
•
• Reach 2 0.14 acre S
Total • 3.01 acres •
• :
Indirect impacts from noise would be mitigated by erected sound barriers.
Cannon Road Extension Project I • City of Carlsbad, California
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Conceptual Mitigation Plan for Reaches 1 and 2
41 1.1.5 Types, Functions, and Values of the Turisdictional Areas to be Directly or Indirectly
Impacted
Types
The existing plant communities identified within the project area include open water, brackish
marsh, disturbed riparian scrub, and southern willow scrub. The southern willow scrub onsite
occurs along Macario Canyon Creek and Agua Hedionda Creek. Common 'native species include
arroyo willow (Salix lasiolepis), black willow (Salix goodingü), and mulefat (Baccharis
sa1icfo1ia). This habitat is primarily found in loose, sandy, or fine. gravely alluvium deposited
near stream channels.
Brackish marsh, occurs in areas which support both saltmarsh and freshwater plant species, and
therefore, is often found at the mouth of canyons near lagoons. Common native species within
this habitat include pickleweed (Salicornia virginica), brassbuttons (Cotula coronopfolia), sedge
(Carex sp.), rush (Juncus sp.), cattail (Typha sp.), and salt-grass (Distichlis spicata).
The disturbed riparian scrub onsite is dominated by mulefat, coastal isocoma (Isocoma veneta),
and coyote bush (Baccharis pilularis). This habitat occurs within the study area in the large basin
at the western end of the project and at the eastern end of the project on the north side of the
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creek. The desiltation basin is located outside the right-of-way and appears to be maintained. The
habitat in this area consists of relatively young growth and the soil shows evidence of recent
plowing. The disturbed riparian scrub habitat at the' eastern end of the site is located within the
right-of-way between the creek and El Camino Real. This habitat is poorly developed and is
dominated, by mulefat and coastal isocoma.
Open water and sandy wash occurs where Cannon Road would cross Agua Hedionda Creek.
Open water habitat does not have emergent vegetation, but may have plants that float on the
surface or are submerged.
Functions and Values
The primary function of the waters in the area is the transport of surface and groundwater flows
from the watershed to Agua Hedionda Lagoon. Associated functions and values are discussed in
this section with emphasis on the habitat functions that depend on these waters.
Functions and values. of the existing southern willow' scrub, brackish marsh, disturbed riparian scrub and open water habitats include contributions to local water quality, wildlife habitat,
recreational uses, and public access. A qualitative assessment of functions and values is presented
in this section.
Cannon Road Extension Project ' ' ' City of Carlsbad, California
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Conceptual Mitigation Plan for Reaches 1 and 2
A study of soils and groundwater associated with the proposed mitigation site in Macario Canyon
was conducted by Woodward-Clyde Consultants (1990). The affected waters and wetlands on
Reach 1 are located downstream and within approximately 1,100 feet of the Woodward-Clyde
study area. Groundwater attributes of the affected area and mitigation site are expected to be
similar. In June 1990, groundwater was located within 5 to 13 feet of the ground surface. The
elevation above mean sea level (AMSL) of these observations are 16 feet, 17 feet, and 20 feet.
The report concludes that the water table occurred at 16 feet to 17 feet AMSL. The location
where the depth-to-groundwater is approximately 5 feet is located adjacent to the existing channel.
It was indicated that this may represent a local perched water zone.
Non-quantitative observations of the surface water flow in Marcario Canyon made by Tetra Tech
during the spring and early summer of 1996 indicate that water flows in this stream during the
early summer. It is likely that these waters and wetlands are supplied by groundwater discharge
during the dry season. During the wet season these areas probably function as a recharge zone
when over bank flows occur. The similar topographic position and elevation suggest that affected
waters and wetlands on Reach 2 have similar characteristics.
Wetlands and riparian habitat provides nutrient removal and transformation functions. The
affected areas are located downstream of agricultural fields used for the production of peppers
during 1996. Inspection of an aerial photograph (Aerial Fotobank 1995) and orthophoto mapping
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from 1988 (City of Carlsbad 1991) indicate that these fields have been cropped for at least the
previous 9 years. The application of fertilizers to these cropped areas likely results in the
transportation of leached nutrients into the stream. In addition, nutrients from natural and non-
agricultural manmade sources are expected to enter the affected stream and groundwater systems.
While the relatively small extent of the affected habitats may limit the quantity of nutrients
removed or transformed, they are expected to contribute to enhanced water quality and nutrient
resources both within the stream system and in Agua Hedionda Lagoon.
The affected southern willow scrub and disturbed ripàrian scrub habitat modify flood flows by
increasing the roughness coefficient. This reduces flow velocity and may result in the spreading
of high flow waters and the increase of surface area where recharge can take place. Marsh
vegetation is less resistant to flows and probably has less effect on the velocity and distribution.
of flood flows.
Crosby, Mead, Benton' & Associates (1990), conducted a Sedimentation Basin Analysis for
Reach 1 of Macario Canyon. They estimated that approximately 1.93 tons of fine- and
medium-textured sand and 0.82 tons of silt are eroded each year from the shrub covered hills of
Marcario Canyon. They suggest that most of this is transported through the canyon and deposited
in the upper reaches of Agua Hedionda Lagoon. They further suggest that construction of
roadways and embankments at the mouth of the lagoon have impeded the movement of sediment
into the Pacific Ocean.
Cannon Road Extension Project • City of Carlsbad, California
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Conceptual Mitigation Plan for Reaches 1 and 2
Where the velocity of flowing water is reduced, sedimentation generally increases. Deposited
sediments are "banked" until resuspended and transported away from the site. The binding action
of the roots of southern willow scrub vegetation' is expected to enhance sediment stabilization
where this habitat occurs. Marsh habitat also binds sediment with a substantial root system and
may increase sediment deposition during low to moderate flows. The transportation of sediments
into Agua Hédionda Lagoon is in part controlled by these riparian habitat functions. Sediments
also provide substrate for riparian and wetland vegetation along the unnamed stream.
The value of the affected habitat for moderation of stream transported sedimentation to Agua
Hedionda Lagoon is rated as low to moderate due to the small size of the affected area. The high
value of the lagoon habitat is the primary reason for including the moderate designation. The
relatively small amount of sediment that is deposited within the unnamed creek and its adjacent
floodplain is of high value in the context of the riparian community.
Both southern willow scrub and marsh vegetation shade water that flows through them and may
moderate or reduce water temperatures. Water temperature is an important habitat characteristic
for. aquatic fauna. Faber, et. al (1989) indicates that water temperature affects numerous stream
functions including processing of organic matter, chemical reactions and concentrations, metabolic
rates of stream invertebrates, and cues for life-cycle events. Shading may prevent summer water
temperatures from reaching lethal levels for fish and invertebrates. Stream shading by the affected
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habitats is therefore expected to enhance habitat characteristics for both in-stream and benthic
fauna.
The value of stream shading provided by the affected habitat is considered high for the reaches
of Macario Canyon and Agua Hedionda Creek between the project area and Agua Hedionda
Lagoon. The large volume of water in Agua Hedionda Lagoon is likely to greatly dilute the
thermal contribution of this stream and, in this context, stream shading is expected to have a low
value.
Habitat
The affected waters and wetlands also provide habitat functions and values for wildlife.
Potentially affected wildlife includes two species listed as endangered by the USFWS.
Least Bell's vireo ( Vireo belli pusillus), occurs in the affected southern willow scrub habitat within
Reach 1. This species is dependent on riparian forest, woodland, and scrub habitats in southern
California. Two male southwest willow flycatchers (Empidonax traillii extimus) were observed
in adjacent southern willow scrub habitat on June 7, 1996. These birds were not observed on a
subsequent survey (June 21, 1996) and were probably moving through the area. Southwest willow
flycatchers may occasionally use the affected southern willow scrub habitat. No other species
listed as threatened or endangered, by the USFWS are known to occur in the affected reach. Least
Cannon Road Extension Project City of Carlsbad, California
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Conceptual Mitigation Plan for Reaches 1 and 2
S Bell's vireo and southwestern willow flycatchers have not been observed in the affected reach of
Agua Hedionda Creek. However, one least Bell's vireo was observed within the willow woodland
habitat of Agua Hedionda creek adjacent to the study area and right-of-way in July 1995.
Other bird species observed during least Bell's Vireo surveys conducted in Macario Canyon
include snowy egret (Egretta thula), great blue heron (Ardea herodias), Nuttall's woodpecker
(Picoides nuttallii), common yellowthroat. (Geothlypos trichas), black-headed grosbeak
(Pheucticus melanocephalus), brown-headed cowbird (Molothrus ater), and others. Mammals
detected in the study area include coyote (Canis latrans), California ground squirrel (Spermophilus'
beechey:), and raccoon (Procyon lotor). It is anticipated that several rodent species also occur in
these habitats.
The only aquatic species known to use these habitats is the mosquito fish (Gainbusia affinis). It
is expected that several amphibians and numerous invertebrates occur in the affected waters and
wetlands.
Due to the presence of least Bell's vireo, the affected habitat is considered to have high value.
In addition, the relatively high number of species observed during field surveys indicates the
affected habitat is a factor in maintaining local species diversity. This also contributes to the
rating of high habitat value.
Currently, the riparian area in Macario Canyon is used as habitation by transients and agricultural
workers. Human habitation of the affected area probably reduces the ability of the canyon's
riparian zone and wetlands to provide habitat for wildlife. Therefore, the affected area's full value
as wildlife habitat is not expressed.
These hydrologic and biologic functions occur in the regional context of coastal southern
California and within the watershed of Agua Hedionda Lagoon. The waters and wetlands of the
project area condition water flows, sediment movement, and nutrients and affect the quality of
water that eventually, enters the lagoon. The waters, habitats, and wildlife of Agua Hedionda
Lagoon represent regionally important resources. While the total 'affected acreage (3.01 acres).
is relatively small compared to the watershed of the lagoon, these functions contribute
proportionately to the lagoon ecosystem.
Recreational Use/Public Access
The affected waters and wetlands provide the public with limited recreational opportunities.
Birding and walking activities probably occur, but data is not available to determine the level of
use. Off-road vehicle use was frequently observed within the Macario Canyon study area. The
presence of human habitation may reduce public access and recreation opportunities.
Cannon Road Extension Project . City of Carlsbad, California
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Conceptual Mitigation Plan for Reaches 1 and 2
No hunting, fishing, or other consumptive uses are known to occur within the affected waters and
wetlands. A moderate value level is assigned to the recreational uses/public access functions of
the site.
2.0 GOAL OF MITIGATION
This section addresses the type of habitat to be created and/or enhanced, functions and values of
these habitats, estimated time lapse, and estimated cost. Since this mitigation plan is written at
the conceptual level, time lapse and estimated cost components of the analysis are treated at a
general level.
2.1 TYPE OF HABITAT TO BE CREATED/ENHANCED
The mitigation effort would result in the creation of southern willow scrub habitat suitable for
least Bell's vireo and marsh habitat.
2.2 FUNCTIONS AND VALUES OF HABITAT TO BE CREATED
The functions and values associated with the created habitat-are expected to be similar to those
describe in Section 1.1.5.
S 2.3 TIME LAPSE
The mitigation effort would be implemented prior to construction of the project. The desired
timeframe for establishment of the created habitat is 1 year. Therefore, there would be no time
lapse between the impact and mitigation.
2.4 ESTIMATED COST
This report is meant to guide the project engineers and landscape architect in the preparation of
a detailed mitigation plan that will include earthwork estimates, detailed planting plans, and other
project components that significantly affect cost. However, the City has made a preliminary
estimate of $250,000 per acre plus land costs.
3.0 FINAL SUCCESS CRITERIA
The final success criteria are presented in Table 3-1. The revegetation plan was developed as
mitigation to restore comparable or increased biological habitat for habitats lost during
construction'. The revegetation concept and this report were prepared to comply with the
regulatory conditions set forth by the ACOE, CDFG, and the CCC. The USFWS has indicated
that meeting the criteria presented in Table 3-1 or detecting occupance of the southern willow
Cannon Road Extension Project City of Carlsbad, California
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Conceptual Mitigation Plan for Reaches 1 and 2
scrub habitat by least Bell's vireo will satisfy their concerns for project mitigation (U.S. Fish and
Wildlife Service 1992)
Table 3-1
Project Success Standards and Measures to be
Taken if the Standard is Not Met
Standard ,. Measure if Standard Not Met
70% groundcover (visual estimate) based on hydroseed Reseed/replant
development
Establishment of all species planted Reseed/replant. Substitutions possible'
80% healthy container tree plantings ' Replace with same species/size
80% survival of,tree plantings'
' 'Replant
80% survival of remaining shrub plantings'' Replant
Height standards met for all trees ' Replant or receive remedial
mesures, substitutions possible
Tree Height Standards'
Cottonwoods ' ' ' '
S Sycamore '
10 feet
9 feet
Willows ' ' ' ' 11 feet
Mulefat, sandbar willow, elderberry , 6 feet '
95% survival of tree plantings' , ' , ' Replant
80% survival of shrub plantings' , Replant
80% groundcover by all species ' , , Additional seed or container plantings
as recommended by revegetation
designer
Canopy cover standards met for trees and shrubs , Replant or receive remedial
measures, substitutions possible,
Canonv Cover Standards'
Willow riparian woodland , 80% '
Brackish marsh 80%
Notes: 'At the discretion of the ACOE, dead container plants can be mitigated for by naturally invading seedlings.
'Mean height in feet.
3A1l canopy covers. given in percentages; '
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City of Carlsbad, California
Conceptual Mitigation Plan for Reaches 1 and 2
3.1 TARGET FUNCTIONS AND VALUES
It is anticipated that those functions and values described in Section 1.1.5 will be substantially
reproduced by the created habitat. The proposed plant palettes provide opportunities for a higher
diversity of riparian trees and shrubs than currently occur in the affected habitats.
Southern willow scrub is an early successional phase of more complex riparian woodlands and
forests (Holland 1986). This vegetation type generally becomes established after sever scouring
events create the open, moist, mineral-based substrate typically required for willow germination
(Faber et. al 1989). During its first 15 to 20 years of growth, it may have a lower species
diversity than more successionally advanced riparian woodlands. The plant palette for this target
vegetation includes tree, shrub, and understory species that are anticipated to provide resources
not available in the affected wetlands (Table 3-2). The inclusion of taller growing trees is
expected to produce habitat with enhanced structural diversity. As succession proceeds, this
habitat is expected to become southern cottonwood willow riparian forest.
The planting pallet for marsh vegetation is also designed to enhance plant species diversity in the
target vegetation relative to the affected habitat (Table 3-3). This may be accomplished by
planting recommended species in the plant palette at appropriate locations relative to the
inundation level. For example, mule fat is best planted at the edge of the target marsh habitat
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rather than in deeper water where cattail and bulrush are expected to become the dominant
species. Since the salinity of both soils and water on the proposed mitigation area vary with
location, the plant palette has been designed to include species that tolerate a wide range of
salinites.
The mitigation plan will integrate southern willow scrub and marsh plantings to provide adjacent
edges. Edge habitats are expected to have higher structural diversity and provide additional
opportunities for wildlife species.
.3.2 TARGET HYDROLOGICAL REGIME
The target hydrological regime is similar to that present on the affected areas. The majority of
the hydrological functions are generated at the scale of the unnamed streams watershed rather'than
within the proposed mitigation area. The source of water will remain seasonal runoff and
groundwater discharge. Seasonal flooding will occur at similar rates and periodicities. The flow
direction will remain substantially the same and the size of the watershed is not expected to change
significantly. Water quality and sediment transport functions are also expected to be similar to
the affected habitats. .
Cannon Road Extension Project City of Carlsbad, California
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Conceptual Mitigation Plan for Reaches 1 and 2
• Table 3-2 .
S
Plant Species Recommended for Cannon Road-Reaches 1 and 2
• Willow Scrub Revegetation Site at Macario Canyon, Carlsbad
No. Per Acre or
Scientific Name Common Name Container Size Pounds Per Acre
•
Willow Riparian Woodland
Container
0
Overstory Plants
Salix goodingii Black Willow 1 gal 250
Salix lasiolepis . Arroyo Willow 1 gal 250
Populus fremonzü . Fremont Cottonwood 1 gal •.. 16
Platanus racemosa Western Sycamore 5 gal 16
Baccharis salicifoliä Mulefat I gal 335
Salix exigua Sandbar Willow I gal
Subtotal Plants/Acre •
Understory Container
947
!lants
Rosa californica Wild Rose 1 gal 30
Sambucus inexicana Mexican Elderberry 1 gal 50
Vitis girdiana Wild Grape 1 gal 100
Rubus ursinus California Blackberry 1 gal 30
Ribes indecorum Winter Current 1 gal
Subtotal Plants/Acre
TOTAL PLANTS/ACRE
Understory Hydroseed
•
• Anemopsis ca1fornica
••
Yerba mama 2 lbs*
Artemisia douglasiana Mugwort 2 lbs
Artemisia dracuñculus Tarragon 2 lbs
Cotula coronopifolia Brass Buttons 1 lbs
Melilotus officinoiis Yellow Sweet Clover 4 lbs
Pluchea odorata March Fleabane 2 lbs
Solidago caljfornica California Goldenrod 2 lbs
Fesruca megalura Foxtail fescue 3 lbs
Notes: *Pounds per acre should be confirmed with the native seed nursery. Pounds may vary based on viability of that particular
crop. • S S
Cannon Road Extension Project Cay of Carlsbad, California
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•
0 Conceptual Mitigation Plan for Reaches I and 2
Table 3-3
Plant Species Recommended for Cannon Road-Reaches 1 and 2
Marsh Revegetation Site at Macario Canyon, Carlsbad
No. Per Acre or
Scientific Name Common Name Container Size Pounds Per Acre
Biackish Marsh.
Container Plants
Juncus aculus Spiky rush 1 gal 100
Pluchea odortua Marsh fleabane 4 inch 300
Igal 100
Anemopsis californica Yerba mansa 4 inch. 300
igal loo:
Salicornia subrerminalis Glasswort 4 inch 300
igal 1C)0
Frankenia sauna Alkali heath 1 gal 100
Baccharis salic4folia Mulefat 1 gal 31
Hymenoclea inonogyra Hymenoclea 1 gal
TOTAL PLANTS/ACRE 1,362
Hvdrosèed Mix
Juncus aczaus. Southwestern Spiny Rush 316s
Scirpus californica Bulrush 5 lbs
Artemisia douglasiana Mugwort 2 lbs
Cotula coronopifolia Brass Buttons 1 lb
Solidago californica California Goldenrod 2 lbs
Typha sp. Cattail 2Jha
TOTAL POUNDS SEED/ACRE 10
Hydrologic factors partially controlled by the design of the mitigation area include duration,
periodicity, and depth of ponding and flooding. These factors are controlled in part by the
elevation of the site relative to the thaiweg of the stream. Relatively low areas are characterized
by deeper waters that may remain inundated longer when flooding occurs. Periodicity of flooding
may be higher in low areas. Relatively high areas have a shorter duration, less frequent, and
shallower flooding. The target hydrological conditions are those created by approximating the
conditions existing in the affected habitat.
An additional hydrologic function that can be influenced by project design is the depth to
groundwater (DTG). The ACOE (1990) has indicated that the optimal DTG for willows and
Cannon Road Extension Project • City of Carlsbad, California
14 0
Conceptual Mitigation Plan for Reaches 1 and 2
cottonwoods is thought not to exceed 6 feet. Mule fat grows where DTG is between 0 and
10 feet. Therefore, the grading plans will specify these DTGs for areas planted with riparian. trees
and shrubs..
Dominant marsh plants are emergent wetland species and require saturated or inundated soils year
around. The marsh area will be designed to have standing surface water year around. Therefore,
the grading plans will specify that areas planted to marsh vegetation must have groundwater at the
surface which gradually grades into standing water approximately 3 feet deep.
The preferred DTG or depth of inundation for the dominant plant species will be an important
factor in determining the final elevation of grading in the target habitats. The marsh habitat
should have a depth.of no greater than 3 feet and should slope gradually upward toward the edge.
This will provide the variety of inundation depths required for the recommended species in the
plant palette. . .
Since DTG and depth of inundation are expected to be the most crucial factor for the long term.
survival of the target vegetation, they should be given preference over considerations of duration,
periodicity, and depth of flooding.
3.3 TARGET JURISDICTIONAL ACREAGE TO BE CREATED/ENHANCED
The target jurisdictional acreage for this mitigation plan is as follows:
OF Southern willow scrub 2.91 acres
Marsh . . . 0. 10 acre
Total 3.01 acres
The mitigation effort will also remove pampas grass (Cortaderiajubata) from 28 acres of existing
wetland habitat in Macario Canyon. This is expected to allow the reestablishment of native
riparian and wetland flora. As native plant species regain dominance, habitat values for wildlife
are expected to improve. . .
4.0 THE PROPOSED MITIGATION SITE
4.1 LOCATION OF THE MITIGATION AREA
The proposed mitigation site is located in Marcario Canyon approximately 1,100 feet upstream
of the affected waters and wetlands (Figure 3 and Plate 1). This site was chosen because it is
close to the impacted area, requires relatively little grading, has surface contours that can be
Cannon Ro4 Extension Project ... City of Carlsbad, California
15
3
I
7
-to
01 MY TETRA TECH INC.
LEGEND
Proposed Mitigation Site
Proposed Marsh Area
SDG&E Wires
-- - 20' Gas Easement Per RBF
@6 Soil Sample Sites
Proposed Mitigation Sites
Macario Canyon
Figure 3
16
Conceptual Miiigation Plan for Reaches I and 2
modified to take advantage of existing groundwater and surface water hydrology, and is on land
currently owned by the City of Carlsbad.
4.2 OWNERSHIP STATUS
The City of Carlsbad currently owns the proposed mitigation site and lands adjacent to it. The
mitigation area will remain in the ownership of the City of Carlsbad following completion of the
project. Long-term protection and management of the site will remain the responsibility of the
City of Carlsbad.
Known water flows to and from the site are the result of local runoff, agricultural tailwaters, and
possibly urban runoff from streets and developed areas within the watershed. These flows are not
currently controlled.
Permission to access the site may be obtained from the City of Carlsbad.
4.3 EXISTING FUNCTIONS AND VALUES OF THE MITIGATION AREA
The proposed mitigation area was selected from several candidate areas in Macarió Canyon
(Figure 3). This area is large enough to accommodate the 3.01 acres of proposed mitigation. The
•
. existing functions associated with the proposed mitigation area are dominated by the site's upland
nature and current land use. The habitat is characterized by agricultural fields of annual row
crops on gentle slopes. These slopes contribute surface runoff to the stream and percolation of
surface water into the groundwater supply. They may also transport runoff from adjacent portions
of the agricultural fields. Nutrients may also be transported to the stream system in the form of
fertilizer salts. Habitat functions currently occurring on the proposed site include foraging by
species capable of using agricultural fields.
The value of these functions to wildlife is relatively low. The potential for this habitat to serve as
a source of fertilizer salts and pesticides further reduces its habitat value. The site's value as
agricultural production is limited by its small size.
4.4 PRESENT AND PROPOSED USES OF THE MITIGATION AREA
The proposed use of this area is mitigation for the Cannon Road Wetland Mitigation Project. The
present use of the mitigation area is agricultural production, human habitation, and watershed.
A gas transmission pipeline owned by San Diego Gas And Electric (SDG&E) crosses Marcario
Canyon in the vicinity of the site. The pipeline is adjacent to the area (Figure 3). The majority
of the area is far enough from the pipeline to avoid potential land use conflicts. A shooting range
is located upstream. .
Cannon Road Extension Project City of Carlsbad, California
17
Conceptual Mitigation Plan for Reaches 1 and 2
S All adjacent areas are owned by the City of Carlsbad. The existing uses include agricultural
production on the slopes northeast of the proposed site. The slopes southwest of the site are
currently -used as habitat and watershed. Several dirt-surfaced roads traverse the area.
Recreational use occurs on these roads. SDG&E has existing right-of-ways for a gas transmission
pipeline and electrical transmission lines on adjacent lands. 0
Proposed uses for areas adjacent to the site include a park and golf course on the slopes currently
in agricultural production. The proposed Cannon Road would cross Marcário Canyon
approximately 1,100 feet northwest of the site (Figure 3 and Plate 1).
4.5. ZONING
Lands on and adjacent to the proposed mitigation site are zoned as open space.
5.0 IMPLEMENTATION PLAN
5.1 RATIONALE FOR EXPECTING IMPLEMENTATION SUCCESS
The rationale for expecting successful implementation of the proposed mitigation include the City
of Carlsbad's strong commitment to this effort and the favOrable physical conditions on the site.
The City's commitment will lead to the selection of an implementation team with experience in
riparian and wetland mitigation. O'Day Consultants will use this Conceptual Mitigation plan as
the basis for additional studies to provide the detail necessary for the final plan. These studies
include:
Field survey to tie in mitigation areas and property lines;
Preparation of legal, plat, and closure documentation;
Earthwork calculation;
Detailed grading plan;
Hydrology study;
Erosion control plan;
Final grading cost estimate; and
Specifications for the work to be completed.
Soil salinity tests were made within the proposed mitigation area to assess suitability for the
proposed effort. The results of these tests are presented in Table 5-1. These samples were taken
at the locations shown on Plate 1. The ACOE (1987) indicates that soils suitable for planting to
non-salt tolerant species should have ECe values of 4.0or less. The results indicate that soil
salinity within the sampled areas varies frOm 2.5 ECes on.the higher elevation portions of the
proposed area to an ECe of 6.6 adjacent. to existing riparian vegetation. Four of the seven
samples have ECes greater than 4.0. To further assess the salinity profile, samples were taken
Cannon Road Extension Project City of Carlsbad, California
0 18
Conceptual Mitigation Plan for Reaches 1 and 2
S at depths of 4 inches to 6 inches, 12 inches, and approximately 16 inches at Location 1. These
samples have the following ECes of 6.6, 4.8, and 3.2, respectively. This indicates that the upper
'4 to 6 inches of the soil has the highest salt content. This sample was taken in an area where
riparian vegetation now grows. This suggests that established onsite vegetation will tolerate this
level of salinity in the upper soil. It is likely that if the salinity is managed during the early stages
of the revegetation effort, riparian vegetation can be successfully established.
Table 5-1
Soil Salinity Test Results
• Sample Location pH Eçe PPT
1 4to6 inches" 7.9 6.4 4.1
1 12 inches 7.9 4.8 3.1
'1 >16 inches 6.5 3.2 2.1
2 6,to8inches 7.4 6.6 4.2
3 6 to 8 inches 7.2 6.3 ' 4.0
4 6to'8 inches 7.6 4.0 2.6
5 6to8 inches 7.7 5.9 3.8
6 6to8'inches 6.9 ' 2.5
,
1.6
7 6to8 inches '. 6.9 2.2 1.4 '
Notes: pH based on saturated soil paste.
Ece calculated on a saturation extract. '
PpT equal toEcex.64.
It is recommended that the Final Mitigation Plan include measures to thoroughly test the salinity
of soils in the mitigation area; and if necessary, reduce soil salinity in areas that would be planted
to southern willow scrub This may be accomplished with a soil amendment such as gypsum.
Gypsum replaces sodium ions with calcium allowing the sodium to be leached out of' the upper
soil.' An additional measure may include revegetating areas with marsh vegetation on soils with
higher ECes, particularly where these occur at the 'lower elevations of the mitigation site.
Water samples were also tested for salinity and ranged from 7.68 patts per thousand (ppt) adjacent
to Agua Hedionda Lagoon to 2.43 ppt at, the proposed mitigation site. The samples from reaches
of the stream near the mitigation site have relatively low salinities. 'This Suggests that the waters
in the mitigation area may not be sufficiently salty to maintain a brackish marsh habitat if, allowed
to flow through the created habitat on a year-round basis.: The final design should incorporate
ways to optimize the salinity .f the water and soil in the brackish marsh area.
S Cannon Road Extension Project ' City of Carlsbad, California
19
Conceptual Mitigation Plan for Reaches 1 and 2
5.2 RESPONSIBLE PARTIES
The parties responsible for the implementation of the mitigation plan include:
Project Proponent:
Address:
Preparer of
Mitigation Plan:
Preparer of Final
Mitigation Plan:
5.3 SCHEDULE
The City of Carlsbad
2075 Las Palmas Drive
Carlsbad, California 92009-1576
Attention: Ms. Sherri Howard
Tetra Tech, Inc.
591 Camino de la Reina, Suite 640
San Diego, California 92108.:.
(619) 718-9676 •.
Attention: Ms Betty Dehoney
O'Day Consultants
7220 Avenida Encinas, Suite 204
Carlsbad, California 92009
(619)931-7700
Attention: Mr. Patrick O'Day
The schedule for timing of site preparation and planting will be provided as part of the Final
Mitigation Plan. The optimal time for installation of the plant.materials is fall or early, winter. However, with irrigation, the area may be-planted during the fall, winter, or spring.
5.4 SITE PREPARATION
The grading or landscape contractor will be responsible fOr all site preparation. The details of
site preparation are being prepared by O'Day Consultants and will,. be included in the final plan.
A biological monitor will be onsite during final site preparation to verify correct placement of
plant materials and make minor adjustments to the final landscape plan, if warranted, based on
the final .grading and hydrology plan.
Optimally, site preparation should begin in mid-September or as soon as the least Bell's vireo is
not present. This allows the project to take advantage of any rainfall during the winter and spring
months. Planting during this season also allows the plants to become established prior to heavy
rainfall and possible flooding. All trash will be removed from the mitigation site prior to weeding
and subsequent planting and seeding. If hydrology studies indicate that the chosen site is likely
Cannon Road Extension Project . City of Carlsbad, California
20 .
t
Conceptual Mitigation Plan for Reaches 1 and 2
to be flooded, the final plan will include measures designed to moderate the velocity of water
crossing the revegetation area. If such measures are not feasible, the possibility exists that
replanting after a flood may be necessary.
The soil on the graded areas may have relatively low nutrient levels. Prior to initiation of planting
or hydroseeding, the soil will be tested to determine which nutrients may be required. The use
of fertilizers in native revegetation projects is somewhat controversial as the enriched soil can also
provide ideal growing situations for weedy species that may compete with native plants.
The success of revégetation efforts can be enhanced by providing an inoculum of mychorizal
fungi. This may be accomplished by obtaining leaf litter and surface soils from existing riparian
habitat with similar soil chemistry. It is recommended that inoculum be obtained from the
affected waters and wetlands and/or riparian habitat adjacent to the revegetation area. Inoculum
should only be taken from areas free of invasive weed species.
5.5 PLANTING PLAN
The proposed revegetation site is located within Macario Canyon (Figures 2 and 3). Tree species
to be used include: black willow, arroyo willow, Fremont cottonwood (Populus fremonriz),
western sycamore (Platanus racemosa), and Mexican elderberry (Sambucus mexicana). Shrub
•
species include: mulefat, sandbar willow (Salix hindsiana), wild rose (Rosa ca4fornica),
California blackberry (Rubus ursinus), and winter current (Ribes indecorwn). Additional species
that would be seeded onto the site include yerba mansa (Anemopsis californica), mugwort
(Artemisia douglasiana), San Diego sagewort (Artemisia palmer,), brass buttons (Cotula
coronopjfolia), southwestern spiny rush (Juncus acutus), yellow sweet clover (Melilotus
officinalis), marsh fleabane (Pluchea odorata), California goldenrod (Solidago calfornica), and
foxtail fescue (Festuca megalura).
Plant Palettes
(
The plant palette to be used in the revegetation of marsh and southern willow scrub will consist
of a combination of container planting and seed Tables 3-2 and 3-3 provide lists of recommended
plants and seeds. The availability of these species should be confirmed with a native plant nursery
and seed supplier prior to completion of the fmal landscape drawings. If required, changes in the
plant palette will be reviewed by the monitoring biologist. Changes to the plant palette will be
consistent with the overall intent of the mitigation design and must be species native to southern
California riparian systems. Initial planting will consist of large and small specimens planted at
densities high enough to achieve the goal of attaining the cover criteria in 1 year.
Plant material will be purchased from reputable nurseries specializing in native species. In
addition, the seed stock will be purchased from a company which continuously collects seeds of
Cannon Road Extension Project City of Carlsbad, California
21
Conceptual Mitigation Plan for Reaches 1 and 2
appropriate species in Southern California. If the nurseries or seed companies do not have stock
on hand, onsite collection may occur in the affected habitat. These species can be stored or grown
in the nursery until ready to plant. Generally, a nursery requires 4 to 6 months to deliver an order
of this magnitude.
The final planting layout should cluster tree species and allow for some clusters of shrubs to
provide structural diversity (Figure 4). Wild rose, California blackberry, and winter current
would be planted along the upland edge of the site along with the western sycamore and Mexican
elderberry. The blackberry and rose should be used to form a natural buffer to minimize human
intrusion into the area.
Planting of the marsh area (Figures 3 and 5) will require a flexible planting pallet. The pallet will
include species adapted to a variety of inundation and salinity regimes. This is necessary since
the exact soil moisture and salinity characteristics of the area cannot be predicted prior to final
grading. In addition, the newly graded site is not expected to be in equilibrium with the site
hydrology, and conditions of salinity may change as an equilibrium develops. Planting a broad
palette allows selection to occur and enhances both the short-term and long-term likelihood that
the site will succeed and provide the target functions and values.
The created marsh will have an area subject to extended periods of inundation on which cattail and
•
bulrush are expected to establish. Bulrush is generally more adapted to deeper water than cattail.
Therefore, cattail will be planted in the shallower water and bulrush in the deeper areas. A
transition zone planted to both species is expected to allow competitive mechanisms to establish
the dominant species (Figure 5).
The marsh edge would be characterized by saturated, but non-inundated, soils or soils that are
inundated for only a short period. The planting pallet for marsh edge (Table 3-3 and Figure 5)
includes species adapted to a range of conditions of soil moisture and salinity. The initial planting
would be expected to adapt dynamically to site conditions and selective mechanisms would
determine the final species composition and distribution of the marsh edge habitat.
Planting Specifications
Some areas may require grading to provide correct hydrologic functions. Marsh vegetation should
be planted adjacent to the existing stream to minimize required grading and take full advantage
of the existing hydrology (Figure 5). The site should be graded and contoured, and irrigation
should be installed early enough to allow the planting of the marsh component of the vegetation
during warm weather. Hydroperiod and water depth significantly affect the establishment of
emergent wetland vegetation (Poiani and Johnson 1989). These factors can be controlled most
Cannon Road Extension Project City of Carlsbad, California
22
MI
A M, Overstory Container Plants
Salix goodingii Black Willow
Salix lasiolepis Arroyo Willow
Populusfrenioniii Fremont Cottonwood
Platanus raceniosa Western Sycamore
Baccharis salicifolia Mulelat
Salix exigua Sandbar Willow
B M Understory Container Plants
Rosa calfornica Wild Rose
San:bucus nze.xicana Mexican Elderberry
Vitis girdiana Wild Grape
Rubus ursinus California Blackberry
Ribes indecorum Winter Current
C M Understory hydroseed
Aneniopsis caIfornica Yerba mansa
Artemisia douglasiana Mugwort
A rienhisia dracunculus Tarragon
Cotula coronopjfo!ia Brass Buttons
Meliotus officinalis Yellow Sweet Clover
Pluchea odorata March Fleabane
Solidago ca1fornica California Goldenrod
Festucarnegalura Foxtail fescue
Riparian Planting Design for 50'x 50' Cell
TETRA TECH INC.. Figure 4
Marsh Edge Containers
1 Juncus acutus Spiny Rush
2 Pluchea odorata Marsh Fleabone
3 Aneniopsis californica Yerba Mansa V
• 4 Salicornica subtenzinalis Giasswort
V 5 Frankenia sauna Alkali Heath
6 Baccharis salicfolia Mule Fat
7 Hyrnenoclea nionogyra Hymenoclea
10 Feet
V
Soil Surface
Water Table - - - - - - - - - - - -
Approximately 3 Feet
I West East'
Emergent Wetland Detail
i I
1yyyy
T'rN
V ',J'" k;r;i
rt I:'
".
TyT.r'ry'r,rT,rTyYy !! '&!'r!y!!yr_'ts...
V EmergentWetiand Containers
Scirpus caljfornicus bulrush
Increasing Water Depth
V
LIII Typha latjfolia cattail
[-I!J Conceptual Marsh Planting Design
TETRA TECH INC. . • V
V Figure 5
Plan for Reaches 1 and 2
S I easily prior to the onset of ra . Warm weather is also expected to enhance the success of
emergent planting Cattail nd bpsh ants should have leaves attached to the rhizomes when
they are planteLLs.provId oxygen supply for the establishing rhizomes. Rhizomes
planted without attached leaves have a lower survival rate (Bedish 1967).
- D4iji -D
Southern willow scrub will be planted where the DTG does not exceed 6 feet. Areas where the
target vegetation is southern willow scrub should be planted after October 1 to reduce hot weather
stress and to allow establishment to occur during the cool, wet portion of the year. All areas will
be planted with container specimens and seeded with the appropriate hydroseed mix. Planting
densities would be high to allow attainment of the cover goals after 1 year of growth. Densities
may be increased by planting cuttings in addition to the specified container stock. However, due
to potentially high mortality, the cuttings, should not be included in survival counts.
Approximately 25 percent of the planted container stock would be at or above the height goal to
enhance the probability that this goal would be met during the first year. Container plants will
be planted prior to the application of the hydroseed. Hydroseed should be applied mechanically
with a slurry. A hydroseed company experienced with native seed applications should be retained
to complete this task.
Container trees and shrubs will be planted using standard horticultural practices: excavating a
planting hole twice the diameter of the root ball, filling the hole twice with water, and leaving the
S plant crown approximately 1 inch above grade after planting. Plants will be placed in soils that
have been thoroughly watered before planting, and watered immediately after planting. Any roots
wrapped around the rootball will be loosened.. The plants should be planted in clusters of three
to five, simulating natural patterns.
The monitoring biologist will be present onsite during the planting and seeding procedures on an
as-needed basis. The monitoring biologist should conduct a fmal check of the site after the
planting is complete. The final check will document that plants were appropriately placed by the
contractor, hydroseed slurry has been correctly applied, and the correct species have been used.
5.6 IRRIGATION PLAN
Irrigation will be supplied for this site. The most feasible source of water is the irrigation system
of the farm operation adjacent to the east edge of the proposed mitigation site. It is anticipated
that irrigation will be buried PVC pipe with overhead sprinkler heads. Although the use of
irrigation will be temporary, it will be permanently installed to reduce vandalism. Final irrigation
design will be conducted by a landscape architect and reviewed by the monitoring biologist.
40 Cannon Road Extension Project . , City of Carlsbad, California
25
Conceptual Mitigation Plan for Reaches 1 and 2
0 5.7 AS-BUILT CONDITIONS
The City of Carlsbad will submit a report to the ACOE within 6 weeks of site preparation and
planting describing the as-built status of the mitigation project. Separate reports will be submitted
for grading, planting work, and erosion control measures, if completed within 6 weeks of each
other. The City will also provide the concerned agencies topographic maps showing as-built
contours of the mitigation area. These maps will indicate the location of plantings and any other
installations or structures.
6.0 MAINTENANCE DURING MONITORING PERIOD
The revegetated areas will require regular maintenance including inspection of the site for erosion
problems, weed invasion, irrigation adequacy, herbivory, unhealthy or dying plants, removal of
trash and actions necessary to prevent off-road vehicle use and. illegal, dumping. These
maintenance activities will be implemented throughout the monitoring period.
6.1 REPLACEMENT OF DEAD OR DISEASED PLANT MATERIAL
All container plant materials will be inspected by the biological monitor 90 days after planting.
At that time, dead plants will be replaced in-kind by the contractor. If disease or insect damage
•
is detected, an assessment of the causal agents will be made and appropriate action will be taken.
All replacement plantings will be made in late fall or winter. Thereafter, plantings will be
assessed monthly during the monitoring period. Dead plants will be replaced by the City of
Carlsbad. Disease and insect damage will also be assessed and appropriate actions taken as
necessary for the full monitoring period.
Seeded areas will be assessed 120 days
. after seeding and monthly thereafter for a 1-year
monitoring period or until performance standards are met. Seeded areas determined by the
biological monitor not to have obtained 50 percent coverage or better are to bereseeded at the
expense of the contractor at 120 days, and thereafter if necessary, at the expense of the City of
Carlsbad.
6.2 WEED. CONTROL
Weeding prior to seeding is important since non-native species will compete with the native
seedlings: An aggressive weed eradication program will be implemented prior to site preparation,
planting and seeding, and continue over the maintenance and monitoring period. Weedy species
are present around the project site and include Brazilian pepper tree (Schinus terebinthfolius), tree
tobacco (Nicotiana glauca), Bermuda grass (Cynodon dactylán), sweet fennel (Foeniculum
vulgare), pampas grass (Cortaderia selloana), wild radish (Raphanus sativus), castor bean
(Ricinus com,nunis), mustard (Brassica sp.), non-native grass, and other invasive plant species.
Cannon Road Extension Project City of Carlsbad, California
. . 26
Conceptual Mitigation Plan for Reaches 1 and 2
Weed removal and control methods include:
Removal of specific weedy species including pampas grass, tree tobacco, and
- Brazilian pepper tree through foliar application or cut-stump treatment with an
appropriate herbicide;
Hand removal of entire plant including the root system; and
Girdling of larger trees or shrubs.
The specific method will be recommend by the montormg biologist.
Weed abatement techniques will vary depending on species. Small shrubs should be removed by
hand; however, the size of the plant will determine the feasibility of complete removal.. If plants
are too large to dig out by the roots, they can be cut back at the base, then the cut base can be
painted with an appropriate herbicide as recommended by the biological monitor.
Under the current permits, pampas grass removal is to be conducted on 28 acres within the
canyon. After initial removal of pampas grass, the contractor should check the area each year for
a 5-year period. If regrowth has occurred, .additional applications should be made.
6.3 PRUNING AND STAKING . .
No pruning or leaf litter removal will take place within the mitigation site since the goal is to
create natural habitat fuAictions. Therefore, dead branches will be left on the shrubs and trees and
leaf litter and fallen branches will not be cleared away from the planting. Pruning may be done
only if required for insect and/or disease control. Trees in 15-gallon or larger containers should
be staked. . .
6.4 EROSION CONTROL.
An erosion control stock will be included in the hydroseed mix. This species should be an annual,
fast growing species which does not readily re-seed. The native seed company will be able to
provide recommendations for such a crop., The correct species should provide erosion control
during the first year. This will allow the native seed to germinate and develop the following year.
Native vegetation will provide erosion control for the remainder of the monitoring period.
65 SITE ACCESS
Measures to prevent off-road vehicles ingress into the site will be included in the final, plan.
Maintenance crews and the biological monitor will be responsible for reporting vandalism and
Cannôfl Road Extension Project . • City of Carlsbad, California
27
,
Conceptual Mitigation Plan for Reaches 1 and 2
trespassing to the City. Barrier plants such as blackberry and rose could be used to form a natural
buffer to reduce human intrusion into the area.
6.6 COWBIRD TRAPPING
Cowbird trapping is required by the USFWS under the Biological Opinion for Cannon Road (U.S.
Fish and Wildlife Service 1992). Cowbird traps should be set every 100 linear yards along
Macario Canyon (5 traps total) in the riparian habitat during the least Bell's vireo breeding season
(May through August). The trapping program will be operated to avoid checking the traps on
weekends and holidays. Traps would be supplied with food, water, and at least one live cowbird
to lure others into .the trap. At the end of the season any live cowbirds would be properly
disposed of. Cowbird trapping would occur for the entire monitoring period. All trapping must
be conducted by persons holding a live cowbird trapping permit from the USFWS.
7.0 . MONITORING PROGRAM
An important component of any revegetation/mitigation program is documentation of progress
until the specified monitoring period is completed. General observations will be important in
documenting areas of poor growth or cover, dead or dying plants, weed invasion, erosion
problems, and inadequate hydrology.. Documentation will be provided by a monitoring biologist.
The primary goal of the revegetation effort is to establish self-sustaining marsh and southern
willow scrub habitat. Monitoring will be accomplished by a qualified biologist with appropriate
credentials and experience.
The monitoring program will use a variety of qualitative and quantitative procedures to document
the changes in growth and density of the desired species within the sampled areas. One of the
most important procedures will be standardized observations of the entire site to provide a general
record of trends within the mitigation site. Quantitative studies will be conducted to obtain cover
estimates, densities, and monitor changes in species diversity. All changes in growth and
survivorship will be documented to determine the success of establishment over the monitoring
period. . .
7.1 HORTICULTURAL MONITORING
The biological monitor will inspect the mitigation site monthly after the installation of the plant
materials. The responsible maintenance staff at the City of Carlsbad will participate in each site
visit to discuss any remediation or maintenance measures required. The entire site will be
assessed qualitatively for evidence of erosion, weed invasion, hydrological problems, vandalism,
and plant mortality. Notes on the general health and growth of the container plants and
hydroseeded areas will be made during these visits. The results of the horticultural monitoring
L Cannon Road Extension Project . -. City of Cadsbad, California
28
Conceptual Mitigation Plan for Reaches 1 and 2
will be included in the annual report required by the resource agencies. If immediate attention
is required, an interim letter report will be sent to the City after each qualitative monitoring
period.
7.2 BOTANICAL MONITORING
Quantitative data will be collected twice yearly during the monitoring period. Information
gathered will include survivorship of container stock, species cover, species composition, tree
height, percent native versus non-native species, and species density of understory seeded areas.
Quantitative measurements may include, but not be limited to, permanent 1 meter x 1 meter
quadrants placed at random locations within the mitigation site. These locations will be sampled
each year. Quadrant sampling will be used to determine percent cover of the herb and seedling
layer. The herb and seedling layer will include all plants less than 0.5 meter high'. Twenty-five
meter line intercept transects will be used for collection of cover data for the tree and shrub
layers. A 6-meter belt transect will, be placed along each 25-meter transect to sample tree and
shrub density. Height measurements will be taken of each tree and shrub rooted within the
6-meter belt. Average height of vegetation layers will also be estimated. Photographic
documentation points will be established at one end of each transect and photographs will be taken
at each monitoring period. The data will be analyzed and reported at the end of the monitoring
year.
7.3 REPORTING
At the end of the year, the biological monitor will submit an annual report to the City of Carlsbad.
The report will include results of survival, percent cover, density, tree' height and girth,
germination of seeded areas, and wildlife present It will be the responsibility of the City of
Carlsbad to submit the reports to the appropriate resource agencies.
Annual reports will be submitted to the ACOE and other involved agencies. These reports will
assess growth and progress toward the final success criteria. Annual reports will include the
following information:
A list of names,' titles, and companies of all persons who prepared the content of
the annual report and participated in monitoring activities for that year;
A copy of ACOE permit, any attached Special Conditions, and any subsequent
letters of modification, as an appendix;
Analysis of all quantitative monitoring data (success, failure, and remedial action).
Graph and table format is preferred;
Cannon Road Extension Project City of Carlsbad, California
29
Conceptual Mitigation Plan for Reaches 1 and 2.
Prints of all included monitoring photographs (colored photocopies are acceptable);
Maps identifying monitoring areas, transects, planting zones, etc.', as appropriate
(see Appendix A for figure format information); and
Copies of all field data sheets shall be available for ACOE review upon request
(U.S. Army Corps of Engineers 1993).
8.0 COMPLETION OF MITIGATION'
The mitigation effort will be completed when the City of Carlsbad nbtifies the ACOE and receives
written confirmation that the ACOE is in agreement.
81 NOTIFICATION OF COMPLETION
When the initial monitoring period is complete and if the City considers the final success criteria
have been' met, the City will notify the ACOE of completion in the'fmal annual report.
8.2 CORPS CONFIRMATION.
S The City understands that following the receipt of the final annual monitoring report, the ACOE
may-require a site visit to confirm the completion.
9.0. CONTINGENCY MEASURES
9.1 INITIATING PROCEDURES . '
If the an annual performance criterion is not met for all or any portion of the mitigation project
in any year, or if the final success criteria are not met, the City will prepare an analysis of the
cause or causes and, if determined necessary by the ACOE, will propose remedial action for
approval.
9.2. ALTERNATIVE LOCATIONS FOR CONTINGENCY MITIGATION
If mitigation efforts are not successful at the chosen area' (Plate 1), mitigation may be
accomplished on other portions of the proposed site.
Cannon Road Extension. Project City of Carlsbad,' California
30
Conceptual Miligation Plan for Reaches 1 and 2
9.3 FUNDING MECHAMSMS
The funds available for the implementation of contingency measures have not been determined to
date. This information will appear in the Final Mitigation Plan or will be provided to the ACQE
prior to beginning work on the mitigation effort.
9.4 RESPONSIBLE PARTIES
The City of Carlsbad will have final responsibility for implementing, monitoring and contingency
efforts.' The contractors who will be responsible to the City for these project components have
not been determined.
10.0 REFERENCES
Aerial Fotobank, Inc.
1995 Aerial Photograph of the project area. Scale 1 inch = 200 feet. Negative Number
CVSD95:80xx. Flown February 2, 1995.
Bedish, J.W. '
1967 Cattail Requirements and Their Significance to Marsh Management. American
Midland Naturalist. Vol. 78.*
City of Carlsbad
1.991 Map. Orthophoto Mapping. Stale, 1 inch ='100 feet. Flown September-October
1988.
,
Crosby, Mead, Benton and Associates
1990' 'Personal Communication. Letter from Mr. A.W. Urquhart, P.E. with Crosby'
Mead Benton and Associates to Mr. Paul Webb, California Coastal Commission. 10 May.
Faber, P.A., E. Keller, A. Sands, and B.M. Massey
1989. The Ecology of Riparian Habitats of the Southern CaIfornia Coastal Region: a
Community Profile. U.S. Fish and Wildlife Service Biology Report 85(7.27).
Holland, R
1986 Preliminary Description of the Terrestrial Natural Communities of California.
California Department. of Fish and Game. Sacramento, California. '
Poianii K.A. and Johnson, C.W. '
Effect of Hydroperiod on Seed Bank Composition in Semi-Permanent Prairie Wetlands.
Canadian Journal of Botany. Vol. 67.
Cannon Road &tension Project ' , ' ' ' , ' City of Carlsbad, California
31 C
Conceptual Mitigation Plan for Reaches 1 and 2
U.S. Army Corps of Engineers .
1993 Habitat Mitigation and Monitoring Guidelines. Los Angles District. 01. June.
1990 Draft Review, and Analysis of Drought Tolerance of Riparian and Estuarine
Species. Prepared by The Chambers Group. Los Angles District. October.
1987 Fulton: Las Coches Mitigation Area: A Case Study in Native Plant Revegetation
Los Angeles District. Proceedings of the Second Native Plant Revegetation Symposium.
U.S. Fish and Wildlife Service . .
1992 Biological Opinion. Letter from J. D. Opdycks, U.S. Fish and Wildlife Service to
Cot. Charles Thomas, U.S. Army Corps of Engineers. 07 April.
Wôodward-Clyde Consultants .
1990 Report of John Moossazadeh, Woodward-Clyde Consultants to Mr. W.
McC1oskey, The Buie Corporation. 02 July.
Cannon Road Extension Project City of Carlsbad, California