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HomeMy WebLinkAboutCT 97-09; La Costa Lucky Sav-On Shopping Center; Tentative Map (CT) (11)Vegetation Analysis Wetland Determination for La Costa Plaza Carlsbad, California September 16.1997 Prepared for: American Stores Properties, Inc. 6565 Knott Avenue Buena Park, CA 90620-1158 Prepared by: Vegetation Analysis Wetland Determination for La Costa Plaza Carlsbad, California September 16.1997 TABLE OF CONTENTS 1.0 2.0 3.0 4.0 5.0 6.0 Summary of Findings Introduction Methods and Survey Limitations Results 4.0.1 Wetland Determination 4.0.2 Botany - On-site Habitats 4.0.3 Botany - Off-site Habitats Rare / Endangered Species Sensitive Habitats References Wetland Determination Form 1 2 2 4 4 7 8 10 12 14 15 Appendix A - Plant Species List Prepared for: American Stores Properties, Inc. 6565 Knott Avenue Buena Park, CA 90620-1158 Prepared by: « . c > RECEIVEDPlanning Systems: Greg Evans, Landscape Architect LA #3900 Fred Sproul, San Diego County Certified Biologist SEP 1 6 1997 2111 Palomar Airport Road, Suite 100 £ITV nn rAot CQAP* ParkhaH PA Q^OOQ vrAKLotlADCarlsbad, CA 92009 PUNNING DEPT. Vegetation Analysis Wetland Determination La Costa Plaza Carlsbad, California September 15,1997 1.0 Summary of Findings This report provides an analysis of vegetation and wetland determination along the San Marcos Creek corridor where it is adjacent to the northern property line of La Costa Plaza in Carlsbad, California. La Costa Plaza is an existing commercial development vegetated with ornamentals. The biological character of the creek corridor was studied to a distance of 3007 from the property line, and mapped to within approximately 2007 of the property line. In this area San Marcos creek has been channeled by past development, and the vegetation that presently exists is significantly dominated by non-native, weedy species. Several wetland plant communities occur along the channel. The wetland delineation line occurs no closer than 15' from the northern property line, and parallels the creek at an approximate elevation of 8 feet MSL. Development within the property line should not significantly impact these wetland plant communities. Upland vegetation that occurs both on-site and off-site is not considered sensitive, except for a very small area of off-site Disturbed Coastal Sage Scrub that will not be significantly affected by proposed development. Based upon the data collected during this biological assessment, it is our opinion that no significant adverse direct or indirect biological impacts will occur to sensitive biological resources in San Marcos Creek or Batiquitos Lagoon due to the proposed project. The indirect impacts that may occur due to the proposed project presently occur in large measure due to surrounding development. The additional indirect impacts caused by the proposed project are insignificant adverse impacts. La Costa Plaza VegetationAnalysis / Wetland Determination 1 2.0 Introduction The subject property exists in a densely developed portion of Carlsbad. It is located at the northeastern intersection of El Camino Real and La Costa Avenue, an area affected by the 100 year flood plain of San Marcos Creek. The property is bordered to the north by San Marcos Creek, to the west by El Camino Real, to the south by La Costa Avenue and to the east by commercial development. The property exists entirely as a commercial development, with over 99% of the property is occupied by ornamental vegetation, buildings and support infrastructure. The area surveyed as the subject of this report is on-site, adjacent to the northern property line, and an area within 100 yards of the property line. The survey area was inventoried to document vegetation species present, with a focus on plant community classification, sensitive species identification, and wetland determination. EXISTING CONDITIONS The project site exists as a commercial development built on sandy loam soils that slope northward to the existing San Marcos Creek. Natural drainage patterns have historically carried all of the storm water runoff from the project site into the creek. Along the northern property line and in the creek bottom, tidal influences have occurred in the past. The soils within the creek influence range from clay to very fine sand. The northern side of the creek across from the project site is also developed, and is used as overflow parking for the La Costa Resort. The creek carries water year-around, and is the primary freshwater source for Batiquitos Lagoon to the west across El Camino Real. Upstream of the property, intensive urban development occurs within the watershed of the creek, which encompasses many square miles. 3.0 Methods and Survey Limitations The property was surveyed in March, 1997, and again in August, 1997 by Fred Sproul, botanist, and Greg Evans, Landscape Architect, LA #3900. Generally, the La Costa Plaza VegetationAnalysis / Wetland Determination 2 Base: USGS 7.5 minute Encinrtas Quadrangte, CA. NORTH LEGEND 1000 2000 I—SCALE (in ted 4000 LOCATION OF SITE Exhibit 1 Vicinity Map Carlsbad, California La Costa Plaza VegetationAnalysis / Wetland Determination I I I I I I I I I I I I I I I I I I I only native vegetation in the area is the narrow band of mostly disturbed native vegetation that occurs along the creek. This creek habitat and sensitive biological resources nearby are the focus of this study. The study area was assessed to determine the location of native plant communities, and tape measurements were collected to provide accuracy whenever sensitive species or habitats were encountered. Vegetation was assessed by listing all plant species encountered, noting the relative percentage of plants which were dominant within each plant community. In addition to the survey of vegetation associated with the San Marcos Creek Corridor, a wetland determination was conducted to definitively locate sensitive wetland habitats adjacent to the site. Vegetation and other wetland indicators were recorded and mapped. A data form as provided in the 1987 Corps of Engineers Wetlands Delineation Manual is attached. 4.0 Results 4.0.1 WETLAND DETERMINATION Site Conditions The developed property is a pad that slopes south to north, abruptly transitioning into a channeled creek north of the property line. Downstream, it passes beneath a bridge over El Camino Real, and then enters Batiquitos Lagoon. The regularly channeled condition along this portion of San Marcos Creek is the result of previous development of this area. A topographical cross section of the channel proceeding from south to north is as follows: a) the existing developed, sloping La Costa Plaza pad, b) a north facing fill slope (reinforced by rip-rap), c) a low shelf (approx. 30' - 40' wide), or a deposit area for dredged spoils, (occurring on La Costa resort property), La Costa Plaza VegetationAnalysis / Wetland Determination I I I I I I I I I I I I I I I I I I I d) open water, (regularly channeled, approx. 507 wide)(La Costa Resort property), e) a south facing fill slope f) a fill pad that is developed (La Costa Resort property). An outlet for sheet drainage from the existing parking lot exists approximately 375' east of the El Camino Real bridge. Along this stretch of channel, approx. 375 linear feet of rip-rap reinforced fill slope occurs, below which lies a low shelf of sandy deposit material. It appears that the rip-rap reinforced fill slope is designed to control erosion associated to the parking lot sheet drainage outlet. The low shelf may be underwater only briefly during seasonal events, being higher than the perennial water level in the creek. Just east of this drainage outlet, a deposit area for dredged spoils exists at approximately the same elevation as the adjoining developed pad, (see Vegetation Resources Map). The slope, the shelf and the bank of San Marcos Creek are mostly dominated by native plant species that have established since the channel was constructed and the property developed. Each of these three topographic features supports a distinctive vegetative cover. 1. Fill Slope Vegetation - Within the rip-rap area of the fill slope bank, very little vegetation exists. Where rip-rap is absent, one of the following plant communities may occur: 1) Baccharis scrub, 2) Upper Salt Marsh, 3) Ruderal, or Ornamental vegetation. 2. Shelf Vegetation - The shelf is most prominently covered with a highly disturbed Upper Salt Marsh plant community more accurately termed Wetland Ruderal. Several young willow trees and young mulefat shrubs also occur on the shelf. Baccharis scrub also occurs on the shelf, until wetland conditions closer to the bank completely exclude this upland community from establishing. La Costa Plaza VegetationAnalysis / Wetland Determination I I I I I I I I I I I I I I I I I I I 3. Bank Vegetation - The bank of San Marcos Creek is considered Freshwater Marsh. It is bordered with a band of Cattail (Typha dominguensis) that exists on both sides of the creek. Several individual Arroyo willow trees (Salix lasiolepis) also occur in this bank area. These trees occupy a small area, and do not form an extensive continuous canopy. Cattails and Arroyo willows are indicative of both the permanence and elevation of perennial freshwater in the channel. There appears to be little to no influence from either saltwater or its tidal fluctuations on the hydrology of this site. Wetland Boundary Determination The wetland boundary is determined by the limit of obligate wetland plant species, wetland hydrology, and wetland soil characteristics. This zone occurs in the creek channel mostly in locations where grade changes are acute, (see Vegetation Resources Map). This zone encroaches up-slope near the parking lot drainage outlet where a small stand of Upper Salt Marsh occurs. On the south bank, adjacent to the proposed project, five plant communities occur, at least in part, within the wetland zone. Fresh water marsh, Upper Salt marsh, Southern Willow Scrub, Mulefat Scrub, Baccharis Scrub, and Wetland Ruderal plants. Soils in these areas have a dark anaerobic character typical of permanent wetland conditions. Hydrologic indicators do not show recent flooding or inundation of this area. Turisdictional Authority The Federal Clean Water Act (CWA) regulates activities that affect Wetlands and Waters of the United States as defined by the 1987 Wetland Delineation Manual. Under Section 404 of the CWA, the U.S. Army Corps of Engineers regulates and issues permits for the disposal of dredge of fill in wetlands. Nationwide permits exist for minimal impacts such as those below 1/3 acre to 3 acres in size. More extensive impacts require Individual Permits, including extensive analysis and/or mitigation. Individual permits are required when activities that impact wetlands exceed three acres. La Costa Plaza VegetationAnalysis / Wetland Determination Section 401 of the CWA regulates any other discharges that may affect water quality are regulated by the California Regional Water Quality Control Board (CRWQCB). CRWQCB application and certification procedures require that an analysis and report be made of the types of pollutants expected from the project Mitigation usually requires the project to minimize or eliminate such impacts. The California Department of Fish and Game (CDFG), regulates alterations to the stream bed of wetland habitats under the Fish and Game code, sections 1600-1607. After consultation with CDFG, impacts are permitted for removal and/or alteration of wetlands. If a 1600 agreement is reached, mitigation is often required to reduce project created impacts to a level of insignificance. 4.0.2 BOTANY - On- site Habitats The on-site plant communities of the study area that were encountered are described and area quantities are provided below. Baccharis Scrub (BS) - (0.04 acres) Baccharis Scrub is an upland scrub community that is most frequently found in dry washes and disturbed areas. The species of Baccharis on the site is Coyote Brush Baccharis pilularis var. consanguinea. The only other plant associate of note is goldenbush, Isocoma veneta. This community occupies disturbed areas in drier and upland areas of the site. No sensitive plants or animals are known or expected to use this habitat within the study area. Ruderal Vegetation (RU) - (0.01 acres) Ruderal Vegetation occurs on the site in waste areas along the northern-most edge of the property. The plants that have invaded this area are weedy annual grasses such as Wild Oats (Avena sp.) and Black Mustard (Brassica nigra). No remnants of the former native vegetation persists in these areas, and there is no particular importance of this habitat to any sensitive flora or fauna. La Costa Plaza VegetattonAnalysis / Wetland Determination Disturbed (PIS) - (0.06 acres) An area where dredge spoils and vegetative garbage are dumped occurs along the eastern-most portion of the study area. Here random mounds of dirt and debris, have been discarded and left unmodified. The few plants thriving in this area are upland ruderal species. Developed Remaining portions of the study area support the ornamental plants that attend the development. 4.0.3 BOTANY -Off-site habitats _ Six native plant communities of note occur off-site, none closer than 10' from the northern property line of the subject parcel. These communities were generally in a disturbed, and transitional state, due to the highly variable environmental conditions that exist along stream course banks. Observed were: Baccharis Scrub, Disturbed Diegan Coastal Sage Scrub, Upper Salt Marsh, Freshwater Marsh, Southern Willow Scrub, and Mulefat Scrub. Also observed were Open Water and Disturbed River Bank, wetland environments not supporting plants. Other non- native habitats include: Wetland Ruderal species, Ruderal species, Disturbed areas, Ornamentals and other Developed conditions. Baccharis Scrub (BS) - Off-site Baccharis scrub occurs in the vicinity of the rip-rap reinforced slope and on the low shelf downstream of the parking lot drainage outlet. This upland shrub community is dominated by Coyote Brush, (Baccharis pilularis var. consanguinea) and Coast goldenbush (Isocoma menziesii var. vernoides). Other prominent plants include: Australian saltbush (Atriplex semibaccata) and Tree tobacco (Nicotiana glauca). Disturbed Diegan Coastal Sage Scrub (DSS) - - A small pocket of DSS that includes sagebrush, (Artemesia calif ornica) occurs no closer than 10' from the project La Costa Plaza VegetationAnalysis / Wetland Determination 8 I I I I I I property line, slightly east of the drainage outlet. This community contains at least 40% weedy species. Upper Salt Marsh -(USM) - An inclusion of pickleweed, (Salicornia virginica) occurs no closer than 10' from the project property line, near the mouth of the sheet drainage outlet. A thin band of upper salt marsh (approx. 2'-4' wide) occurs intermittently along the north bank of San Marcos Creek, east of the ECR bridge. West of the bridge, upper salt marsh occurs in various degrees of disturbance primarily outside of the study area where fresh water inundation does not occur. Southern Willow Scrub - (SWS) - Two small dumps of Arroyo willows, Salix lasiolepis. occur just east of the bridge crossing, on the shelf previously described. One live tree and many dead willow trees occur west of the bridge crossing, probably indicating that freshwater inundation or saltwater intrusion is progressively limiting their establishment Mulefat Scrub - (MS) - Two clumps of mulefat scrub occur on the shelf, one near the existing drainage outlet. Freshwater Marsh - (FM) Cattail, Tvpha latifolia. occurs no closer than 35' from the I project property line, primarily in a narrow band along the creek bank. The _ width (approx. 8' each side) of this band of cattails indicates a narrow band of • permanently wet soil conditions along the creek edge. Cattails also occur on mid-channel deposits in the study area. Wetland Ruderal (WR) - Various herbaceous wetland ruderal species occur * interspersed among the other off-site wetland communities. The shelf is most I prominently covered with a highly disturbed Upper Salt Marsh plant community of Pickleweed and Alkali heath (Frankenia salina). Several invasive non-natives occur on the shelf, such as: Russain thistle, (Salsola tragus). Salt cedar (Tamarix sp.). Pampas grass (Cortadiera sp.). Bristly ox-tongue (Picris La Costa Plaza VegetationAnalysis / Wetland Determination 9 echoides) and Spiny clotbur (Xanthium strumarium). Extensive wetland ruderal conditions occur west of the bridge. Ruderal (RU) - Ruderal conditions, (invasive, non-native, weedy species), predominate in the upland areas of creek influence in areas once occupied by native plants. This disturbance is the result of past development that has occurred on both sides of the creek. 5.0 Rare/ Endangered Species The Federal and State Endangered species, (Sterna antillarum browni). California Least Tern is being re-established at Batiquitos Lagoon. Nesting areas have been created and successfully colonized in several locations around the lagoon, the closest being an island colony located approximately 1400 feet from the nearest portion of the proposed project, (median construction along El Camino Real). Because their nesting requirements are very specific, it is unlikely that any nesting birds would occupy areas closer to the project than this island. However, California least terns have been known to utilize freshwater areas similar to San Marcos Creek for foraging. Because of the sensitivity of this species, protection of potential foraging areas is necessary. The project proponent has designed a project that completely avoids all encroachment into the existing creek corridor, except for storm water runoff, to be discharged in a controlled manner. The existing commercial development presently discharges storm water runoff into the creek, and does not use current technology to purify the water leaving the site. The proposed drainage system will use a desiltation basin, and a filtration system that is satisfactory to the California Regional Water Quality Control Board (CRWQCB). The water released by the proposed project will be of substantially higher quality than what is presently discharged. Provided that runoff entering the creek does not contain harmful pollutants, as defined by the CRWQCB, no significant adverse impacts are La Costa Plaza VegetationAnalysis / Wetland Determination 1 0 anticipated to bird populations, and specifically the California least tern due to the proposed project. Southern Willow Scrub habitat, where it is of much greater scale and associated with more extensive riparian systems, is known to support several sensitive bird species, including the Federal and State Endangered (Vireo pusillus bellii). Least Bell's vireo and the Federal Endangered (Empidonax traillii extimus). Southwestern Willow flycatcher. However, the several willow individuals near the site are not extensive enough to provide significant nesting or foraging opportunities. The largest nearby riparian system containing extensive Southern Willow Scrub is in the Green Valley corridor, just south of the project site. Only one Least Bell's vireo has been observed in recent years in that 38 acre willow stand. This bird was not detected again, leading the project biologists to conclude that the bird was just migrating through the area. Neither of these species are expected to use SWS habitat in the vicinity of the project site. Freshwater marsh habitat, where it is associated with large saltmarshes may support the Federally and State Endangered (Rallus longirostris leviper). Light-footed clapper rail. The eastern basin of Batiquitos Lagoon is habitat for this bird species. However, the San Marcos Creek channel is not suitable for nesting or foraging because of the following factors . The creek is narrow, with a linear band of cattails primarily along the bank, not the extensive cover that rails require. The bridge over El Camino Real is a substantial impediment, blocking rail access to the creek. Saltmarsh is habitat for the State Endangered (Passerculus sandwichensis beldingi). Bering's Savannah sparrow. The saltmarsh along San Marcos Creek is seriously degraded with invasive, non-native species, and is discontinuous with salt marsh habitat in Batiquitos Lagoon. It is that Belding's Savannah Sparrow would use the San Marcos Creek area to any significant degree. La Costa Plaza VegetationAnalysis / Wetland Determination 1 1 6.0 Sensitive Habitats Habitats considered biologically sensitive by the CDFG occur entirely outside of the property line. However, within the study area several sensitive habitats occur, including: Southern Willow Scrub, Freshwater marsh, Upper Salt Marsh, Mulefat Scrub, and Disturbed Coastal Sage Scrub. Of these, the only upland community present is Disturbed Coastal Sage Scrub. The very small size (0.03 acres), its discontinuity with and other coastal sage scrub and its highly disturbed nature, are circumstances that make it insignificant for use as habitat by (Polioptila californica californica). California Gnatcatcher. No California gnatcatchers are expected to use the site. The wetland resources that are the subject of this study, though very small in area, are adjacent to a large estuary system at Batiquitos Lagoon. This lagoon supports threatened and endangered species. The water that flows in San Marcos Creek is a primary source of the freshwater that enters Batiquitos Lagoon. The quality and quantity of freshwater entering the lagoon substantively affects the biological quality of this resource. The entire project area of 11.78 acres drains storm water into San Marcos Creek. To the extent that this water is free of contaminants, as regulated by t he CRWQCB, the biology of the lagoon should not be substantively affected. 7.0 Anticipated Project Impacts The project as proposed does not develop areas outside of the property line. No sensitive habitats are proposed for disturbance by the project. The only direct impacts that may result from the proposed project would result from water quality and flood control issues. The project as designed will potentially discharge increased runoff, because of a larger area of impermeable surfaces proposed by the project. However, the proposed increase in impermeable surface area is only a few thousand square feet, whereas the total watershed of San Marcos Creek is many square miles. The impermeable surface area as a percent of the entire watershed area is insignificant. Therefore, an increase in the magnitude of freshwater entering the La Costa Plaza VegetationAnalysis / Wetland Determination 1 2 lagoon is not a potential significant adverse impact to the existing habitat in the study area or the lagoon itself. The storm water runoff that would issue from the project would be within CRWQCB standards, and would be much cleaner than the present discharge, which enters San Marcos Creek totally unfiltered. Indirect impacts may result from noise and other factors because of the proximity of habitat to the proposed development. Indirect impacts currently occur to the natural habitat of the study area. Furthermore, these impacts are cumulative; they occur as a result of pre-existing development of properties north, south, and east of this site, and area mostly unmitigatable. Sensitive bird species inhabit the Batiquitos Lagoon, but only the California Least Tern may potentially use the open water habitat within the study area. This habitat is likely to be used for foraging purposes only. The possibility exists that certain construction activities may limit least tern use of the habitat. The foraging habitat within the study area is a small portion of their overall foraging range at Batiquitos Lagoon. The actual affect of slightly reduced foraging opportunities during project construction is not likely to be an adverse significant impact. Based upon the data collected during this biological assessment, it is our opinion that no significant adverse direct or indirect biological impacts will occur to • sensitive biological resources in San Marcos Creek or Batiquitos Lagoon due to the ™ proposed project. The indirect impacts that may occur due to the proposed project • presently occur in large measure due to surrounding development. The additional indirect impacts caused by the proposed project are insignificant. I I I I I I I I La Costa Plaza VegetationAnalysis / Wetland Determination 1 3 References Abrams, L. 1923. Illustrated Flora of the Pacific States. Stanford University Press, Stanford, California. Beauchamp, R. M. 1986. A Flora of San Diego County. California. Sweetwater Press, National City, California. Holland, R. F. 1986. "Preliminary Descriptions of the Terrestrial Natural Communities of California." Nongame-Heritage Program, California Department of Fish and Game. Hickman, J. C. 1993. The Tepson Manual. Higher Plants of California. University of California Press, Berkeley, California. 1400 pp. + 1 p. errata Munz, P. 1974. A Flora of Southern California. University of California Press, Berkeley, California. 1086 pp. Skinner, M. W. and Pavlik, B. M. 1994. California Native Plant Society's Inventory of Rare and Endangered Vascular Plants of California. Special Publication No. 1 (Fifth Edition), California Native Plant Society, Sacramento, California. 338 pp. Thomas Bros. Maps, 19%. The Thomas Guide. 1997. La Costa Plaza VegetationAnalysfe / Wetland Determination 1 4 Exhibit 2 Wetland Determination Form DATA FORh 1 DETERMINATION Applicant " Application ?rojeet Number: Name: State; C/4" County: & & Legal Description: Iovrtshtp;A25 Range; *4 U/ Date; ^"ZS-^"! Plot No.; /V/M" _ Section: Vegetation [list the three dominant species in each vegetation layer (5 If only I or 2 layers)]. Indicate species with observed morphologic*! or knovn physiological adaptation* vich an asterisk. Indicator Indicator Status Species Status 6. *&«*+ S*C.. ?) 12. Z of species that «r» OBL, FACW. and/or FAC?V^vC»Other indicators Hydrophytic vegetation: Yes XL_ No . B«»l«; Series and phase ;^/*c«vfft*- ^^-j?" hy<lrlc soils list? Yes ; No Mottled: Yes )C i No . Mottle color; ""— ; Matrix color; Cleyed: Yes ?C So Other indicators; <^/<gycfg]C Hydr.ic soils: Yes _JC No ; Basis; 5orf Hydrology Inundated: Yes : Ko f\ , Depth of standing water: Saturated soils: Yes ; No .X- . Depth to saturated soil: Other Indicators: Wetland hydrology: Yea X ; No . Basis; ^/y/C Atypical situation: Yes /^\ ; No . riSS O Normal Clrcuastanos? Ye; No ^ , Wetland Deteraination: Wetland X^. ; Nonwetland_ Coaaents: ^ JDetermined by: CXxXgX B2 La Costa Plaza VegetationAnalysis / Wetland Determination 1 5 APPENDIX A Plant List for San Marcos Creek Wetland Determinatin Carlsbad, California APIACEAE - CARROT FAMILY * Foeniculum vulgare Sweet fennel ASTERACEAE - SUNFLOWER FAMILY Acourtia microcephala Marsh fleabane * Ambrosia psilostachya Western ragweed Artemisia californica Coast sagebrush Baccharis pilularis var. consanguinea Coyote brush Baccharis salicifolia Mulefat * Isocoma menziesii var. vernoides Coast goldenbush * Picris echoides Bristly Ox-tongue * Xanthium strumarium Spiny clotbur BORAGINACEAE - BORAGE FAMILY Heliotropum curvassivicum Alkali heliotrope BRASSICACEAE - MUSTARD FAMILY * Brassica nigra Black mustard CHENIPODIACEAE - GOOSEFOOT FAMILY Atriplex brewerii Brewer's saltbush Atriplex patula spp. hastata Halbeard-leaf saltbush * Atriplex semibaccata Austrialian saltbush Salicornia vlrginica Pickleweed * Salsola tragus Russian thistle FRANKENIACEAE - FRANKENIA FAMILY Frankenia salina Alkali heath OLEACEAE - OLIVE FAMILY * Olea europea Olive SALICACEAE - WILLOW FAMILY Salix lasiolepis Arroyo willow SOLANACEAE - NIGHTSHADE FAMILY * Nicotiana glauca Tree tobacco TAMARICACEAE - TAMARISK FAMILY * Tamarix sp. Salt cedar ANGIOSPERMS (MONOCOTS) CYPERACEAE - SEDGE FAMILY Scirpus olneyi. Olney's bullrush JUNCACEAE - RUSH FAMILY Tuncus mexicanus Mexican rush POACEAE - GRASS FAMILY * Cortadiera sp, Pampas grass * Cynodon dactylon Bermuda grass * Polypogon monspeliensis Rabbit's-foot grass TYPHACEAE - CATTAIL FAMILY Typha dominguensis Cattails Status Plant Community * Non-native (weed or cult.) ! Classified Sensitive O Offsite in sphere area DEC 2 * 1397 Supplement Vegetation Analysis / Wetland Determination for La Costa Plaza Carlsbad, California December 18,1997 Prepared for: American Stores Properties, Inc. 6565 Knott Avenue Buena Park, CA 90620-1158 Prepared by: Supplement Vegetation Analysis / Wetland Determination La Costa Plaza Carlsbad, California December 18,1997 1.0 Summary of Findings The Lucky Save-on project presently proposed for the corner of La Costa Avenue and El Camino Real has been amended to include a proposed earthen berm near San Marcos Creek. The proposed earthen berm is designed to, reduce potential flooding risk to a Leucadia County Water District facility. It is proposed for a location adjoining the proposed Lucky Sav-on building, and extending eastward adjacent to the stream channel, outside of the 100 year floodway. Additional environmental analysis is necessary to adequately determine if the project as presently proposed will impact significant biological resources. This report provides an analysis of vegetation, of sensitive biological resources, and applies hydrology conclusions reached by others, to assess the potential for significant environmental impacts due to the project as presently proposed. Based upon the data collected during this biological assessment, it is our finding that no significant adverse direct or indirect biological impacts will occur to sensitive biological resources in San Marcos Creek or Batiquitos Lagoon due to the project as presently proposed. The indirect impacts that may occur due to the proposed project presently occur in large measure due to surrounding development. The additional indirect impacts caused by the proposed project are insignificant. 2.0 Introduction / Methods and Survey Limitations The Planning Systems document, "Vegetation Analysis / Wetland Determination, La Costa Plaza, September 16, 1997 provided a conclusion, "that no significant adverse direct or indirect biological impacts will occur to sensitive biological resources in San Marcos Creek or Batiquitos Lagoon due to the proposed project ". The project as presently proposed is virtually the same except for the addition of an earthen berm. Because the berm is the only substantive difference between the previously analyzed plan and the current plan, this supplement will focus primarily upon the berm and its potential environmental affect. When a finding regarding the berm's environmental impact is reached, a cumulative project impact assessment will then be provided. The proposed berm is located on the south side of San Marcos Creek, outside of the 100 year floodway. It abuts the proposed Lucky Sav-on building to the west, and extends easterly, parallel to the Creek (see Exhibit 2, O'Day Consultants "Preliminary SUPPLEMENT - La Costa Plaza Vegetation Analysis / Wetland Determination Grading Plan for L.C.W.D. Earth Berm, sheet 1 of 1, for location and configuration). The berm, designed to serve as a flood control levee, is proposed as approximately 450 ft. long, approximately 44 ft. at its widest point, and a maximum of approximately 9 ft. in height. Its is structurally comprised of 2:1 slopes, north and south facing, with a 10' wide and flat top. Surface runoff from the flat top and the south facing slope are designed to drain into control structures, surface runoff form the north facing slope is seek the creek unassisted. The berm is located almost entirely on L.C.W.D. property, with only a 10 ft wide section located within La Costa Plaza property. A temporary 10 foot wide construction zone is proposed to parallel the northern toe of slope, adjacent to the creek (see O'Day Preliminary Grading Plan). EXISTING CONDITIONS The property was surveyed in March, 1997, and again in August, 1997 by Fred Sproul, botanist, and Greg Evans, Landscape Architect, LA #3900. Generally, the only native vegetation in the vicinity of the proposed berm is the narrow band of mostly disturbed native vegetation that occurs along the creek bank. This creek-side habitat and sensitive biological resources nearby are the focus of this study. The berm is proposed entirely outside of the 100 year floodway, on relatively flat land that is in no case lower than the 11 foot contour as shown on O'Day Consultants Preliminary Grading Plan (Exhibit 2). Across San Marcos Creek on the north bank is La Costa Resort Property, specifically a grassy area used for overflow event parking. The lowest elevation along the north bank across from the berm is approximately the 7 foot contour. The site of the proposed berm was visited during the initial study, and vegetation in the vicinity of the berm is shown on the "Vegetation Analysis Map" (September 10, 1997) as either "Disturbed", "Ornamental", or "Ruderal", or is a developed area of the existing L.C.W.D. facility. No native plant communities exist beneath, or within approximately eighteen feet of the proposed berm. No wetland habitat occurs beneath or within 18' of the proposed berm. Natural drainage patterns have historically carried all of the storm water runoff from the berm site into the creek. Adjacent to the proposed berm, a dredge spoils area composed of fill material, shown as "disturbed" vegetation on the Vegetation Analysis Map, lies between the berm site and the creek bank. These spoils effectively create a backwater bench that will initially pool run-off coming from the north-facing berm slope, prior to unassisted release into the creek at low points along the spoils bank. SUPPLEMENT - La Costa Plaza Vegetation Analysis / Wetland Determination 3.0 Results Hydrology A hydraulic study to determine potential impacts of the proposed berm to San Marcos Creek and adjacent properties has been conducted by Howard H. Chang Consultants. The existing topographical configuration of the Creek area in the vicinity of the proposed berm is structured such that bank overflow caused by large flow events deposits backwater onto La Costa property on the north bank floodway. The study has concluded that the proposed berm will not produce any change in the scour potential of San Marcos Creek or the north bank overflow area within the floodway (see exhibit I, Letter, Howard H. Chang Consultants, and the HEC-2 study by Howard H. Chang Consultants). This finding indicates that berm construction will not increase erosion in San Marcos Creek, or the floodway area, in the vicinity of the proposed berm. The wetland resources that are the subject of this study, though very small in area, are adjacent to a large estuary system at Batiquitos Lagoon. This lagoon supports threatened and endangered species. The water that flows in San Marcos Creek is a primary source of the freshwater that enters Batiquitos Lagoon. The quality and quantity of freshwater entering the lagoon substantively affects the biological quality of this resource. The entire project area, including the north face of the berm, drains storm water into San Marcos Creek. To the extent that this water is free of contaminants, as regulated by the California Regional Water Quality Control Board (CRWQCB), the biology of the lagoon should not be substantively affected. Sensitive Habitats No native plant communities exist on the land to be occupied by the proposed berm, within the temporary 10' wide construction zone, or within 18' of the toe of the berm. Provided that no construction activities occur outside the construction zone, and that all exposed soils are properly planted and maintained, no disturbance of existing native plant communities is anticipated, and no significant adverse impacts are anticipated to native plant communities in the project vicinity. Rare / Endangered Species The Federal and State Endangered species, (Sterna antillarum browni), California Least Tern, have been known to utilize freshwater areas similar to San Marcos Creek for foraging. The location of the proposed berm should not affect water quality, and would not in any way affect foraging opportunities for this species. No significant adverse impacts are anticipated to the California least tern due to the proposed berm. Freshwater marsh habitat, where it is associated with large saltmarshes may support the Federally and State Endangered (Rallus longirostris leviper), Light-footed SUPPLEMENT - La Costa Plaza Vegetation Analysis / Wetland Determination clapper rail. The eastern basin of Batiquitos Lagoon is habitat for this bird species. However, the San Marcos Creek channel is not suitable for nesting or foraging because the creek is narrow, with a linear band of cattails primarily along the bank, not the extensive cover that rails require. The bridge over El Camino Real is .a substantial impediment, blocking rail access to the creek. However, in the event that Clapper rail were to utilize the creek adjacent to the project site, no freshwater marsh habitat will be affect by the proposed berm. No significant adverse impacts are anticipated to the Clapper rail due to the proposed berm. The Federal and State Endangered (Vireo pusillus bellii), Least Bell's vireo and the Federal Endangered (Empidonax traillii extimus), Southwestern Willow flycatcher utilize Southern Willow Scrub (SWS) habitat. No SWS habitat will be affected by the proposed berm, and no significant adverse impacts are anticipated to either of •these species due to the proposed berm. It is highly unlikely that the State Endangered (Passerculus sandwichensis beldingi), Belding's Savannah sparrow would use the salt marsh area east of El Camino Real, near the project site. No salt marsh habitat will be affected by the proposed berm, so no significant adverse impacts are anticipated to this species due to the proposed berm. The Federally Threatened Polioptila californica californica), Coastal California gnatcatcher occasionally utilizes ruderal or disturbed vegetation for foraging purposes when it occupies an adjacent stand of Coastal sage scrub vegetation. A small pocket of disturbed Coastal sage scrub (0.03 acres), that occurs near the berm site is too small to be utilized by gnatcatcher, so no gnatcatcher foraging is expected on the disturbed and ruderal plant communities on or near the berm site. No significant adverse impacts are anticipated to this species due to the proposed berm. 4.0 Project Impacts The previous section have concluded that the proposed berm will not significantly affect the hydrology, sensitive habitats, or sensitive species associated with San Marcos Creek. The only direct impacts that could be anticipated due to berm construction are: 1) uncontrolled erosion during construction, 2) inadequate berm planting / maintenance, 3) a minute increase in surface run-off associated with a berm slope rather than the existing flat surface. Provided that adequate silt fencing and construction work limit lines are maintained, no significant adverse impacts due to construction related erosion are anticipated. Provided that adequate erosion control berm planting and establishment maintenance is implemented, no significant adverse impacts due to establishment related erosion are anticipated. In terms of the minute increase in run-off because of the berm slope, as evaluated against the total watershed of San SUPPLEMENT - La Costa Plaza Vegetation Analysis / Wetland Determination Marcos Creek which is many square miles, no significance impact due to increased run-off is anticipated. Indirect impacts resulting from construction noise and berm maintenance may occur due to the proximity of the proposed berm to creek and near creek habitat. These indirect impacts are either temporary construction related impacts,, or brief maintenance related episodes occurring seldom and on an irregular basis. These indirect impacts are insignificant and largely unmitigatable. 5.0 Cumulative Project Impacts The studies that have occurred to date have found that no significant environmental impacts to sensitive biological resources will occur due to the proposed project. Thusfar, this study has focused on potential environmental impacts associated with the berm only, not in terms of the total project proposed. In cumulative terms, the finding of no significant impact is also appropriate. The project does not significantly alter existing stream properties. No sensitive habitats are proposed for disturbance by the project. No sensitive animals are likely to be significantly impacted by the project as proposed. Based upon the data collected during this biological assessment, it is our opinion that no significant adverse direct or indirect biological impacts will occur to sensitive biological resources in San Marcos Creek or Batiquitos Lagoon due to the project as presently proposed. The indirect impacts that may occur due to the proposed project presently occur in large measure due to surrounding development. The additional indirect impacts caused by the proposed project are insignificant. SUPPLEMENT - La Costa Plaza Vegetation Analysis / Wetland Determination Exhibit 1 Letter, Howard H. Chang Consultants, December 11,1997 Howard H. Chang Consultants ! ' Hydraulic, Hydrolpgic and Sedimentation Engineering P.O. Box 9492 Rancho Santa Fe, CA 92067 (619)756-9050. 594-6380. FAX: (619)756-9460 • December 11, 1997 Ms. Meg Purviance O'Day Consultants . 7220 Avenida Encinas, Suite 204 Carlsbad, CA 92009 Dear Meg: i. Subject: Revision of HEC-2 study for San Marcos Creek at La Costa for American Stores I wish to provide you with the results of the hydraulic study in order to determine the potential impacts of the proposed berm on adjacent properties. The proposed berm will be located along the south bank of the main channel outside the floodway from river mile 2.80 to 2.84. In order to determine if there is going to be any change in the scour potential, it is necessary tq look at the flow velocities under the existing conditions without the berm and the proposed conditions with the berm in place. The computed flow velocities for the main channel and north overbank area within the floodway are summarized below. Channel station river mile 2.S1 2.83 2.85 2.89 2.93 Velocity in the main channel fps Existing conditions 5.9 5.6 6.5 6.1 5.9 Proposed conditions 5.9 5.6 6.5 6.1 5.9 Velocity in the north overbank area fps Existing conditions 5.2 4.9 5.4 5.2 . 5.1 Proposed conditions 5.2 4.9 5.4, 5.2 5.1 It can be seen from the computed velocities listed above that the proposed berm will not change the flow velocity and hence it will not change the scour potential for the adjacent properties north of the channel. ' Please let me know if you have any questions regarding this letter. . i CONSULTANTS " " ' : DEC 15 1997 REOEIVED . Howard H.Chang. Ph.D., P.E. Si SUPPLEMENT - La Costa Plaza Vegetation Analysis / Wetland Determination &^L&<§-^-~.. -~~-^:==S-, ?f^l^---4=i^&s SUBDIVISION BOUNDARY D NEW LOT LINE ^^^M^DB^ t- ^*^">^ v—/ O *,. i ^_: if.:\--—-.., -»„£5i^^f{^^^ y 7V 7 REMOVE EXISTS TING BOUNDARY LINE FENCE STORA&'FAQUTIE$'• \j-£ \ ( //kv^>\/ ^>MH Exhibit 2 PRELIMINARY GRADING PLAN L.C.W.D EARTH BERM LA COSTA PLAZA CARLSBAD, CALIFORNIA LEGEND BERM LOCATION PROPOSED LUCKY SAV-ON BUILDING 0 10 20 40 RTL SOFT 40 SCALE NORTH DECEMBER 23, 1997 GRADING PLAN / BASE SOURCE: O'DAY CONSULTANTS PS # 971248