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HomeMy WebLinkAbout3466; OLIVENHAIN RD WIDENING & REALIGNMENT; RIPERIAN MITIGATION YEAR 6 FINAL REPORT; 2003-12-3030 December 2003 City of Carlsbad Ms. Sherri Howard Associate Engineer Public Works-Engineering 1635 Faraday Avenue Carlsbad, California 92008 Subject: Olivenhain Riparian Mitigation Site: Year 6 Final Letter Report Dear Ms. Howard: AMEC Earth & Environmental, Inc. (AMEC)' submits this final letter report for the sixth year, of biological monitoring of the Olivenhain Riparian Mitigation Site (mitigation site). The mitigation site is located in north San Diego County in Carlsbad, California (Figure 1). This project is permitted under California. Department of Fish and Game ('CDFG) Section. 1601 Streambed Alteration Agreement No. 5-560-94 and U.S.Army Corps. of Engineers (USACE) Section 404 Nationwide Permit No. 95-20096-13H. The permit requirements include the creation, planting, and 5-year maintenance and biological monitoring of 0.5 acre of wetland habitat (0.34 acre of southern willow, scrub and 0.16. acre of freshwatermarsh) and the replacement of 0.21 acre of southern willow scrub and 0.14 acre of freshwater marsh that wer!e temporarily impacted during construction. The permit also addresses the 1.1-acre flood control dike located adjacent to the mitigation area. . . Background The mitigation site is required cOmpensation for. construction-related impacts to wetland habitat associated with the widening of -Olivenhain. Road in Carlsbad, California. The City of Carlsbad (City) is responsible for the mitigation effort AMEC has performed biological monitoring services for this mitigation site since 1998. AMEC conducted a field visit on 23 July 2003 accompanied by Sherri Howard (City), Terry Dean (USACE),. and'Tamara Spear (CDFG) to discuss the progress of the mitigation site. Jessie Walker (AMEC) informed the USACE and CDFG that most of th.e mitigation site had existed under natural conditions (i.e., .without supplemental irrigation) since 2001 and that a smaller portion ofthe mitigation site had existed under natural conditions since December 2002. To date, the entire mitigation site has existed under natural conditions for 1 year. During the July field visit, USACE informed the City and AMEC that a wetland delineatid'n should be performed to determine the jurisdictional wetland acreage at the mitigation site. Only 'after the determination was completed and a letter report supplied to the regulatory agencies would mitigation site sign-off be considered. 325400000-3005/3151-1203R126.doc Page 1. 1J4 COSTA A 5 A LA PROJECT SITE if Raw N PF NOT TO SCALE Project Location Map FIGURE Biology/Olivenhain 2000/Olivenhain Proj LocA.FH8 Ms. Sherri Howard City of Carlsbad, Olivenhain RiParii9ation Site: Year 6 December2003 Methodology Horticultural Monitoring During the sixth year, horticultural monitoring consisted of three site visits conducted to determine site conditions and to monitor the landscape contractor's maintenance activities. Plant modality, vegetation development, weed establishment, and vandalism were assessed during each visit. AMEC made one horticultural monitoring visit in March, one inApril, and one in December 2003. During the. April and December site visits, AMEC also assessed the two areas that were temporarily impacted, one located along Olivenhain Road and the other on the southeastern corner of the intersection of Olivenhain Road and El Camino Real. Based on observed site conditions, AMEC recommended maintenance measures to the landscape contractor, Native Landscape, Inc. Botanical Monitoring Quantitative botanical monitoring consisted of collecting line intercept data from transects to describe vegetation development, collecting tree heights, and counting dead container plants. Quantitative data were collected for the mitigation site for 5 years; howevif, no quantitative data were collected. during the sixth year since success criteria were achieved after the fifth year of mitigation. During the 5 previous years, the line intercept method was used to quantitatively evaluate the success of the mitigation site. Percent vegetative cover was. obtained using this method. AMEC took line measurements on four transects located throughout the 0.5-acre. mitigation site to determine cover and species composition (Figure 2) in year 5. A representative sapling of trees and shrubs existing in the mitigation area, including both container and volunteer plants, was measured for tree and shrub heights. Tree and shrub heights were collected using a tree height measurement instrument. The health of container plants was visually assessed for container plants installed within the mitigation area. In addition, the number of dead container plants throughout the mitigation area was determined and evaluated against the success standards. Photographs were also taken at the beginning of each transect. The quantitative data collected in year 5 is presented in this letter report for reference purposes. Refer to the Fifth Annual Report Olivenhain Road Widening Wetland Mitigation Area, January 2003, for a complete history and discussion of the mitigation site, including mitigation site photographs. . . . . •. Wetland Delineation AMEC biologists Jessie Walker and Julie Simonsen-Marchant conducted a Clean Water Act (CWA), Section 404, wetland. delineation of the mitigation site on 5 December 2003. Three soil. pits were excavated at .vegetation community transition areas and examined for three wetland indicators - hydrophytic vegetation, wetland hydrology, and hydric soils —as discussed below. The USACE regulates the.discharge of fill material into waters of the U.S. Waters of the U.S. include wetlands and non-wetland water bodies meeting specific criteria. Waters of the U.S. are typically regulated as jurisdictional by the USACE if the drainage exhibits at least intermittent. flow. Evidence of intermittent flow typically includes the formation of bed and bank, debris 325400000-3005/3151-1203R126.doc Page 3 emec! Olivenhain Road Wetland Mitigation Area F I ( 11 R F 2003 2 O/soro/oIivenhnarcmap/flg_4.rxd 12123/03 Ms. Sherri Howard City-of Carlsbad, Olivenhain Ripar tigation Site: Year 6 December 2003 ditiec deposits, and scoured channels. USACE jurisdiction over, waters of the US. extends to the ordinary high watermark (OHWM) of the. feature. As defined by USACE regulations, waters of the U.S. include these traditional drainage features, as well. as a range of other waters, including: All interstate waters, including interstate wetlands; All other waters, including intrastate lakes,, rives, streams; mudflats, sandflats, wetlands, sloughs, prairie potholes, wet meadows, .playa lakes, or natural ponds, for which the use, degradation or destruction of could affect interstate or foreign commerce; All impoundments of waters that fit'the description; Tributaries to any defined waters; Territorial seas; and . . . . . . Wetlands adjacent to waters. . The USACE defines wetlands as: Those areas that are inundated or saturated by surface or groundwater at a frequency and duration sufficient to support, and that under normal circumstance do support, a prevalence or vegetation typically adapted to life in saturated soil conditions: Therefore, under Section 404 of the CWA, an area is considered a jurisdictional wetland if it possesses all three of the following wetland attributes: Hydrophytic vegetation, Wetland hydrology, and Hydric soils. Areas are evaluated in the field for these wetland characteristics according to the methods defined in the 1987 Corps, of Engineers Wetland Delineation ManUal. Hydrophytic vegetation is defined as plant species that grow and are adapted to the conditions of permanently or periodically saturated soils. The presence or absence of hydrophytic vegetation was determined by developing a list of plant species present within the area in 'question, determining the dominant of each species within each strata . (tree, shrub, and herb), and determining the wetland status of each species. Wetland plant indicator status was obtained -from the' U.S. Fish and Wildlife Service (USFWS) National List of Plant Species That Occur in Wetlands: California (Reed. 1988). If more than 50 percent of the dominant vegetation species were classified as obligate, facultative wet, or facultative, then hydrophytic 'vegetation was determined to be present. Wetland hydrology was determined by several factors, including the presence of water in the soil pit, presence of saturated soils, presence' of ponded surface water, drift lines; sediment deposits, and drainage patterns within a wetland. Secondary hydrology indicators include oxidized root channels, water-stained leaves, and local soils survey' data. No recorded flow data were available for. .the site, but aerial photos were used as an indication of wetland hydrology. 325400000-3005/3151-1 203R126.doc Page 5 Ms. Sherri Howard City of Carlsbad, Olivenhain Ripar' itigation Site: Year 6 December 2003 ' Hydric soils are flooded, ponded, or saturated for a period during th growing season sufficient to develop anaerobic conditions in the upper layers, favoring the growth of hydrophytic. vegetation. Soils must meet at least one of the following criteria to be considered hydric: Classified as organic soils (Histosols, except the Folists), Exhibits a histic epipedon, Contains sulfidic materials, . Exhibits a moisture regime that is aquic or peraquic, Exhibits reducing soil conditions,' Exhibits the gleyed 'soil color, or low matrix color, Listedon a hydric soils list. For sandy soils, hydric soils can sometimes be determined by the presence .of high organic matter in the surface horizon or streaking of organicmatter in the subsurface layers. In many cases, soil color is the most diagnostic field tool for determining the presence of hydric soils. Soil color was determined by digging a soil pit'to a depth of 16.inches and determining the matrix, chroma1 and hue of the soil sample of each horizon with Munsell® Soil Color Charts (1975). If the soil was gleyed, had no mottles and a chroma of one. or less, or if mottles were present and the chroma was two or less, the soil was determined to be hydric.. In cases where the soils were sand or recently deposited river sand, a problem area or'natüral atypical situation. occurs.where it is not'possible to determine soil color. In these cases, the .1987 Corps'. manual does not require soil pits, and jurisdictional wetlands are delineated based on other indicators of hydric soils, the indicators of hydrophytic vegetation and wetland hydrology, and professional judgment. Results Horticultural Monitoring Results There, was no plant mortality in the mitigation area and all of the plants, have been without suppleñiental irrigation for 1 to 2 years. Natural recruitment and native plant establishment were noted throughoutthe mitigation area. Many willOw (Salix ssp.) saplings and seedlings are located throughout southern willow scrub portion of the mitigation site. Many additional naturally recruiting species such as giant wild rye. '(Leyrnus condensatus), yerba mansa (Anemopsis. californica), coastal goldenbush (Isocoma menziesii), tall cattail (Typha latifolia); bulrush (Scirpus, maritimus and S. californicus), and alkali heath (Frankenia sauna) were observed inthe mitigation site. Several new species including centaurium (Centaurium venUstum) 'and grass poly (Lythrum hyssopifolium) were located this year for the first time. Several vegetation communities exhibiting several seral stages now exist within the mitigation site. The primary vegetation communities include southern willow scrub, coastal salt marsh, freshwater marsh, 'and upland riparian scrub. Seral stages range from early (southern willow scrub) to mid-successional (freshwater marsh and coastal salt marsh). Many avian and mammalian species have been observed foraging in the mitigation' site inclucflng coyote (Canis 325400000-3005/3151-1203R126.doc Page 6 Ms. Sherri Howard City of Carlsbad, Olivenhain RiPaitiation Site: Year 6 December 2003 latrans), pacific tréefrog (Hyla regilla), lesser goldfinch (Carduelis psaltria), mourning dove (Zenaida macroura), black phoebe (Sayornis nigricans), mice (Chaetodipus sp.), and bobcat (Fe/is rufus). A white-tailed kite (Elanus leucurus majusculus), a sensitive avian species, has been observed perched on a snag in the mitigation site.many times over the past several years. Invasive plants including fennel (Foeniculum vu/gare), Bermuda grass.-(Cynodon dèctylon), tamarisk ('Tamarix ssp.), black mustard (Brassica nigra), bristly ox-tongue (Picris echioides), and yellow sweet clover"(Meli/otus officinalis) were located in the mitigation site. These populations were controlled and/or eliminated during two visits this past year by. Native Landscape, Inc. the landscape maintenance contractor. Vandalism and trash were not problematic in the mitigation site during the past 5 years, but this year people used the sitefor collecting cattails and . other native plants for .seed and the floriculture industry. As a result, the mitigation site vegetation has been cut and somewhat trampled from people walking on it during their collection visits. Botanical Monitoring Results (Year 5) Percent Cover The percent cover standard for year 5 was achieved in 2002; therefore,. no quantitative data were collected in 2003. The total cover for all,-species by year 5 in the 'mitigation area was 135.8 percent '(Table 1). .Native species cover was, 135.5 percent and nonnative species cover was 0.3 percent. The dominant native species was coastal goldenbush with a percent cover of 38.1. Pickleweed (Sa/icornia virginica) was the second most dominant species at the mitigation area with a percent cover of 17.6. Wetland indiôator species such as willow species, bulrush, and tall cattail were not represented in the percent cover data; however, these species' 'do occur in the mitigation area and were, found in areas where the' transects were not placed. Black mustard was the most dominant nonnative species with a percent cover of 0.2, which is extremely low. ' Table I OLIVENHAIN ROAD WETLAND MITIGATION AREA PERCENT COVER (2002) Botanical Name Common Narn/e Absolute Cover (%) Isocoma menziesii * ' coastal'goldenbush ' . 38.1 Sallcomia virginica * . . pickleweed . 17.6 Artemisia palmed * Palmer's sagewort . 16.8 Distichlisspicata * saltgrass ' , ' ' 10.9 Ambrosia psilostachya * . . western ragweed ' 8.8 Leymus condensatus * giant wild rye . 7.4 Frankenia salina * , . alkali heath ' 6.6 325400000-3005/3151-1203R126.doc Page 7 Ms. Sherri Howard City of Carlsbad, Olivenhain RiPari9ation Site: Year 6 December 2003 . amec* Botanical Name ' Common Name 'AbsolUte Cover (%) Baccharis salicifolia * mule fat 4.7 Oenotheraelafa spp. hirsutissima * evening primrose 3.8' Salix exigua * narrow-leaved willow 3.5 Ma/ye/la leprosa * alkali mallow , 2.9 Anemopsis califomica * yerba mansa 2.6 Artemisia douglasiana * Douglas mugwort 2.6 Pluchea sericea * arrow weed 2.4 Encelia califomica * coastal sunflower 1.7 Epllbium diiatum - willow herb 1.6 Sàlix lasiolepis * arroyo willow 1.3 Bacchris p1/u/ads * coyote bush 1.2 Heterotheca grandiflora * telegraph weed .• 0.5 Solanum douglasii black nightshade ' 0.5 Brassica nigra , black mustard ' -. 0.2 Pluchea odorata salt marsh fleabane .0.2 .Picris echioides bristly' ox-tongue ... 0.1 Percent Total Cover ' 135.8 Percent Native Cover 135.5 Percent Nonnative Cover - ' 0.3 * Indicates species native to California. Nomenclature follows. the Checklist of the Vascular Plants of San Diego County 3d edition by Michael G. Simpson and Jon P. Rebman, San Diego State University and San Diego Natural History Museum. Tree and Shrub Heights The tree and shrub height success standard for year 5 was achieved in 2002. The specified tree height success standard is 3.4-meters and the shrub height success .standard is 1.8 meters Of the.'58 trees measured in the mitigation area, 22 were container trees (Table 2). The average height for container trees in the mitigation area was 4.0 meters,' :which achieves the height success standard of 3.4 meters. The average tree height for all trees, including volunteers and unknowns, was 3.0 meters; however, there was no success .standard for volunteer and unknown trees. . Of the 42 shrubs measured in the mitigation area, 9 were container shrubs (Table 2). The average height for container shrubs in'the mitigation area was 3.1 meters, which achieves the height success standard of 1.8 meters. The average shrub height for all shrubs, including volUnteers and unknowns, was .2.5 meters; however, there was no success standard for volunteer and unknown, shrubs. 325400000-3005/3151-1203R126.doc Page 8 Ms. Sherri Howard . City of Carlsbad, Olivenhain Ripar tigation Site: Year 6 December 2003 amec Table ' OLIVENHAIN ROAD WETLAND MITIGATION AREA TREE AND SHRUB CONTAINER HEIGHTS (2002)' Trees Botanical Name Common Name 'Type Heiht °. Sample Size Sallx exigua . ' Narrow-leaved willow Container 2.7 ' 9 Salix exigua Narrow-leaved willow Unknown 2.7 3 Salix exigua' Narrow-leaved willow Volunteer 2.1 29 Salixlasiolepis Arroyo willow Container 5.3 . 13' Salix lasiolepis Arroyo willow ' . Volunteer 2.5' '' 4 Average for Container Trees 4.0 22 Average for All Trees ' ' ' 3.0 " 36 Total ' " . ' . . ' ' 58 Shrubs Botanical Name ' Common Name ' ' Type -:' Height '.'Sarnple Size Baccharis pilularis. '. Coyote bush Volunteer 1.6 ' 5 Baccharis salicifolia Mulefat Container 3.1 ' 9 Baccharis salicifolia . Mulefat Unknown ' 3.0 4 Baccharis salicifolia Mulefat Volunteer '3.4 24 Average for Container Shrubs' ' ' ' ' 3.1 9 Average for All Shrubs ' ' ' i 2.5 . ' 33 Total . ' ' ' 42 Container Plant Success The container tree, and shrub survival success standard'for year 5 has been. achieved. The percent survival success standard for year 5 is. 90 percent for container trees, and 80 percent for container shrubs. No dead container trees or shrubs were located during' the fifth year of the mitigation area. • ' ' • ' 'Wetland Delineation Results ' A total of 0.23 acre- of jurisdictional wetland area was identified within the mitigation area. .The limits of jurisdictional 'wetlands (coastal salt marsh/freshwater marsh)' mapped are shown in Figure 2. The regulatory permits. tequired.that 0,16 acre of freshwater marsh be created at the mitigation site however, there is a higher amount of acreage (0.23 versus 0..16 acre) because the boundary of the mitigation site (mitigation site easement) is greater than the area where the 325400000-3005/3151-1203R126doc Page Ms. Sherri Howard City of Carlsbad, Olivenhain Ripa itigation Site: Year 6 0 December 2003 8i1i7e ' 0.16 acre was Create d. There is also 0.38 acre of southern willow scrub ;and 0.09 acre of upland riparian 'transitional habitat in the mitigation site. Based on the wetland delineation process, ,the City, has met the obligations of the regulatory (USACE and CDFG). permits, as presented in 'the dataforms and photographs in Attachment A. Determination The: City .requests 'concurrence from the regulatory agencies that the City 'has fulfilled allof the' requirements outlined in the regulatOry permits as described' in this letter'report. A final walk-through of the mitigation site will occur only if requested by the regulatory 'agencies upon receiving and reviewing this letter report. If no final wk-through is requested by the regulatory 'agencies, the City will assume that their responsibility"to maintain and monitor the mitigation site under the regulatory permits no longer applie and that concurrence from the regulatory 'agencies that the mitigation site has met all success standards will , have been: granted. Please contact Jessie 'Valker if you have any comments or questions; The City will assume that the regulatory agencies concur with this arrangement unless,we are nOtified to the contrary ' by 30 January 2004. Sincerely, AMEC Earth & Environmental, Inc. Jessie Walker Natural Resource Specialist/Botanist JW:vm Attachment: Figure A-i, Coastal Salt Marsh/Freshwater Marsh at Soil' Pit.,Number 1 Figure A-2, Soil Pit Number I Vegetation Community Figure A-3, Mottles in Soil at Soil Pit Number 1 ' Figure A-4, Coastal Salt Marsh/Freshwater Marsh at Soil Pit.Number 2 Figure A-5, Southern Willow Scrub at Soil Pit Number 3 cc: File Copies(2) / 325400000-3005/3151-1203R11 26.doc Page 10 S S S :..... .. .. -, .- .. S S..-. Sf - •. - : -- ,. •1, S - - r.. - : -. . - '- .5- ::.\:'7 ,..: -S S •. 4.__ . -.. S )S- . - -. S _. - -. . . 54, •_Jd ••_4_ I! 4 1 .5-S •- . :. ••••••/• i-__ - . .- -. . . S - -.i-I. •.. 5• 5 - - / . .4-, S S - 5 554 4. /1 5•..' 5- - •, .••_ /5 4 5 - Jo S.S. fr N.- Coastal Salt Marsh/Freshwater Marsh RmLcro at Soil Pit Number 1 N". / amia Mottles in Soil at Soil Pit Number I Ue-- GRAPHICS/Biology/325400000_3005 Olivenhain/A_3.Fh8 FIGURE -. — —' h - — - ' \ -. - t / I I - II . •l . 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