APPENDIX G BIOLOGICAL SURVEY REPORT FOR THE SAN DIEGUITO LAGOON W-19 RESTORATION PROJECT

Transcription

1 APPENDIX G BIOLOGICAL SURVEY REPORT FOR THE SAN DIEGUITO LAGOON W-19 RESTORATION PROJECT San Dieguito Lagoon W-19 Restoration Project Final EIR November 2018 Appendices

2 FINAL BIOLOGICAL SURVEY REPORT FOR THE SAN DIEGUITO LAGOON W-19 RESTORATION PROJECT SAN DIEGO COUNTY, CALIFORNIA Prepared for: San Dieguito River Park Joint Powers Authority Sycamore Creek Road Escondido, California Prepared by: AECOM 401 West A. Street, Suite 1200 San Diego, California February 2017

3 TABLE OF CONTENTS Section Page LIST OF ACRONYMS AND ABBREVIATIONS... v CHAPTER 1.0 INTRODUCTION Background Project Limits and Purpose Project Limits Purpose of the Proposed Project Project Alternatives CHAPTER 2.0 METHODS Biological Study Area Biological Field Surveys and Data Sources Vegetation Mapping Jurisdictional Waters and Wetlands Delineation Surveys Special-Status Plant Surveys Special-Status Wildlife Surveys CHAPTER 3.0 EXISTING CONDITIONS Vegetation Communities Wetlands and Riparian Vegetation Communities Upland Vegetation Communities Cover Types Jurisdictional Waters and Wetlands Flora Federally Listed Plant Species State-Listed Plant Species Nonlisted Special-Status Plant Species Fauna Special-Status Wildlife Critical Habitat Wildlife Movement CHAPTER 4.0 PROJECT IMPACTS guidelines for determining significance Proposed Project San Dieguito Lagoon W-19 Restoration Project Final BSR Page i

4 Section Page Vegetation Communities Jurisdictional Resources Special-Status Plant Species Special-Status Wildlife Species Wildlife Corridors/Connectivity Alternative B Vegetation Communities Jurisdictional Resources Special-Status Plant Species Special-Status Wildlife Species Wildlife Corridors/Connectivity Alternative C Vegetation Communities Jurisdictional Resources Special-Status Plant Species Special-Status Wildlife Species Wildlife Corridors/Connectivity CHAPTER 5.0 AVOIDANCE AND MINIMIZATION MEASURES CHAPTER 6.0 REFERENCES APPENDICES A Monthly Volunteer Bird Count Results Report February 2016 B Jurisdictional Delineation Report C Plant Species Observed within the BSA D Coastal California Gnatcatcher Survey Reports E Least Bell s Vireo Survey Report F Light-footed Ridgway s Rail and Belding s Savannah Sparrow Survey Report G Pacific Pocket Mouse Habitat Assessment Report H Table of Sensitive Plant Species with Potential to Occur within the BSA I Table of Sensitive Wildlife Species with Potential to Occur within the BSA Page ii San Dieguito Lagoon W-19 Restoration Project Final BSR

5 LIST OF FIGURES Figure Page 1-1 Regional Map Vicinity Map Ownership Proposed Habitat Distribution Wetlands Maintenance and Material Placement Proposed Project Wetlands Maintenance Areas Alternative B Habitat Distribution Alternative C Habitat Distribution Biological Study Area Vegetation Communities and Cover Types in the W-19 Site and BSA Vegetation Communities Disposal Site and BSA Jurisdictional Waters of the U.S Potential Jurisdictional Waters of the State Special-Status Plants Detected in the BSA Special-Status Wildlife Detected in the BSA Limits of Disturbance Proposed Project Alternative B Limits of Disturbance Alternative C Limits of Disturbance LIST OF TABLES Table Page 1-1 Anticipated Inlet Maintenance Requirements after Storm Events Anticipated Interior Wetland Sediment Maintenance Required Alternative B Anticipated Inlet Maintenance Requirements after Storm Events Alternative C Anticipated Inlet Maintenance Requirements after Storm Events Anticipated Interior Wetland Sediment Maintenance Required BSA Acreages by Area Focused Surveys Conducted in the BSA Previous Project Studies Conducted in San Dieguito Lagoon Vegetation Communities and Other Cover Types within the W-19 Site and Buffer (Acres) San Dieguito Lagoon W-19 Restoration Project Final BSR Page iii

6 Table Page 3-2 Vegetation Communities and Other Cover Types within the Disposal Site, Haul Route and Buffers (Acres) Potential Waters of the U.S. and State Occurring BSA Proposed Project Permanent Impacts to Vegetation Communities and Cover Types in the W-19 Site Post-Restoration Vegetation Communities and Cover Types in the Disposal Site and Haul Route Proposed Project Temporary Impacts to Vegetation Communities and Cover Types in the W-19 Site Proposed Project Temporary Impacts to Vegetation Communities and Cover Types in the Disposal Site and Haul Route Proposed Project Permanent Impacts to Listed Wildlife Species Habitat in the W-19 Site Proposed Project Permanent Impacts to Listed Wildlife Species Habitat in the Disposal Site and Haul Route Proposed Project Direct Temporary Impacts to Listed Species Habitat in the W-19 Site Proposed Project Direct Temporary Impacts to Listed Habitat in Disposal Site and Haul Route Alternative B Permanent Impacts to Vegetation Communities and Cover Types in W Alternative B Temporary Impacts to Vegetation Communities and Cover Types in the W-19 Site Alternative B Direct Permanent Impacts to Listed Wildlife Species Habitat in W Alternative B Direct Temporary Impacts to Listed Species Habitat in the W-19 Site Alternative C Permanent Impacts to Vegetation Communities and Cover Types in W Alternative C Temporary Impacts to Vegetation Communities and Cover Types in the W-19 Site Alternative C Direct Permanent Impacts to Listed Wildlife Species Habitat in the W-19 Site Alternative C Direct Temporary Impacts to Listed Species Habitat in the W-19 Site Avoidance, Minimization, and Mitigation Measures Page iv San Dieguito Lagoon W-19 Restoration Project Final BSR

7 LIST OF ACRONYMS AND ABBREVIATIONS BSA Caltrans CDFG CDFW CFR City CNDDB CNPS Corps dba ERCE ESA FTA GPS I-5 JPA Konecny L max MHPA MMU MSCP RWQCB SANDAG SCE SDG&E JPA USDA USFWS Biological Study Area California Department of Transportation California Department of Fish and Game California Department of Fish and Wildlife Code of Federal Regulations City of San Diego California Natural Diversity Database California Native Plant Society U.S. Army Corps of Engineers A-weighted decibel ERC Environmental and Energy Services Co. Endangered Species Act Federal Transit Administration global positioning system Interstate 5 Joint Powers Authority Konecny Biological Services maximum noise level Multiple Habitat Planning Area minimum mapping unit Multiple Species Conservation Program Regional Water Quality Control Board San Diego Association of Governments Southern California Edison San Diego Gas and Electric San Dieguito River Park Joint Powers Authority U.S. Department of Agriculture U.S. Fish and Wildlife Service San Dieguito Lagoon W-19 Restoration Project Final BSR Page v

8 CHAPTER 1.0 INTRODUCTION 1.1 BACKGROUND San Dieguito Lagoon is located within the San Dieguito river valley in the City of San Diego (City), San Diego County, California (Figure 1-1). The San Dieguito Lagoon W-19 Restoration Project (proposed project) would be located within San Dieguito Lagoon, east of Interstate 5 (I-5), south of Via de la Valle, and west of El Camino Real. The proposed project site is located within lands owned by the San Dieguito River Park Joint Power Authority (JPA), California Department of Fish and Wildlife (CDFW), and the City, and is within the Focused Planning Area of the San Dieguito River Park (Figure 1-2). Historically, San Dieguito Lagoon and its adjoining coastal wetlands occupied much of the western San Dieguito river valley and included a mix of vegetated salt and brackish marsh, with associated tidal embayments, sloughs, and mudflats. The San Dieguito wetlands have experienced extensive filling and alteration, beginning as early as the late 1800s. Between these impacts and simultaneous development of the surrounding area, less than half of the historical wetlands remain intact. Consequently, the ecological function of the tidal marsh ecosystem and the regular influence of the ocean tidal waters have been substantially diminished (SANDAG 2011). Development, infrastructure, and the progressive closing of river and lagoon mouths throughout the San Diego region have led to the conversion and loss of coastal wetlands. The restoration of coastal wetlands can offset this historical loss, enhance and maintain sensitive wetland habitats and native species, promote coastal biodiversity within the region, and enrich functional wetland habitat within San Diego. The purpose of the proposed project is to restore coastal wetlands, which would be used as mitigation for transportation projects within the coastal corridor of north San Diego County and would partially offset wetland losses within the San Dieguito River system. The proposed project would restore habitat that historically occurred within the lagoon, taking into consideration constraints now imposed by existing adjacent land uses and other recently implemented and planned projects. The proposed project would encompass an area historically identified as a restoration opportunity by the JPA in their 2000 Park Master Plan for the Coastal Area of the San Dieguito River Valley Regional Open Space Park (Park Master Plan; San Dieguito River Park JPA 2000) and would amend that plan to encompass all of the restoration site, and update its designation to W-19. In addition, the California Department of Transportation San Dieguito Lagoon W-19 Restoration Project Final BSR Page 1

9 Project Location I San Dieguito Lagoon W-19 Restoration Project BSR P:\2012\ _SD_W19\05Graphics\5.4_Proj_Graphics\Figures\Fig1regmap.ai dbrady 7/15/15 Figure 1-1 Regional Map

10 Via de La Valle San Andres Drive Birdwing Open Air Classroom Del Mar Horse Park San Diego Polo Fields DS40 W16 Camino del Mar DEL MAR FAIRGROUNDS W4 NS13 W10 W-19 Restoration Site Fairbanks Ranch Golf Course San Dieguito Road W17 Railroad Jimmy Durante Blvd W2!"^$ W6A El Camino Real Old El Camino Real W3 W1 NS = Nesting Site W = Wetland DS = Disposal Site Source: JPA: Dokken 2015 I 1, ,000 Feet Scale: 1:12,000; 1 inch = 1,000 feet San Dieguito Lagoon W-19 Restoration Project Draft BSR Path: P:\2012\ _SD_W19\06GIS\6.3_Layout\Reports\BSR\Overview.mxd, 1/9/2017, paul.moreno DS36 * The proposed materials placement sites are the same as those used for maintenance dredging required by the SCE Restoration Project (DS-40). Proposed Project Components Project Area Disposal Site Material Placement (Post-Storm Event)* Other Projects/Features Coast to Crest Trail LEGEND 22nd DAA Del Mar Fairgrounds South Overflow Lot Project SCE San Dieguito Lagoon Restoration Project SCE Project Disposal Sites Figure 1-2 Vicinity Map

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12 (Caltrans) and San Diego Association of Governments (SANDAG) identify the site as part of the overall wetland mitigation strategy for infrastructure projects along the North Coast Corridor within northern San Diego County in the Public Works Plan and Transportation and Resource Enhancement Program (Caltrans 2014). The proposed project is intended to be used for mitigation for infrastructure projects being planned by SANDAG, Caltrans, and/or the City (e.g., El Camino Real Bridge Replacement Project). Reserve wetlands and/or uplands for future projects by others could also be established as part of the proposed project. The JPA proposes to restore lagoon functions within part of the lagoon called W-19, or the restoration site, as a part of a larger goal to protect a diverse assemblage of self-sustaining coastal habitats important to the region. The proposed project aims to create and enhance hydrological connections of the lagoon by proposing the creation of tidal salt and brackish marsh habitats and hydraulic connections to the San Dieguito River to sustain them. In addition, disposal of materials excavated from the restoration site would be placed south of the W-19 site on a disposal site partially used previously as a disposal site by other projects (Figure 1-2). Other portions of the San Dieguito Lagoon system have already undergone restoration efforts, and the proposed project would complement existing restoration efforts. Southern California Edison (SCE) implemented the San Dieguito Wetland Restoration Project (SCE restoration project), which encompassed approximately 440 acres between El Camino Real and the Pacific Ocean, adjacent to and west of the proposed project area. The SCE restoration project included excavation, restoration of tidal wetlands, reestablishment of historical uplands, and enhancement and expansion of freshwater and seasonal coastal wetland areas, as well as a public access and interpretation component (USFWS and San Dieguito River Park JPA 2000). The proposed project would be designed to integrate with and expand upon the SCE restoration project. The proposed project would also be designed to accommodate ongoing efforts of wetland creation and restoration west of I-5 and south of the Del Mar Fairgrounds, as well as integrate with the proposed El Camino Real Bridge Replacement Project planned by the City. The brackish marsh and riparian enhancement portions of the proposed project are anticipated to provide mitigation for the City's El Camino Real Bridge Replacement Project (Caltrans 2015). The purpose of this Biological Survey Report (report) is to summarize the biological resources known to occur, or with the potential to occur, in the restoration and disposal sites, as well as to analyze the short-term and long-term impacts (both positive and negative) of the proposed project. This report represents a compilation of both existing information, and specific focused studies conducted for the proposed project. San Dieguito Lagoon and the restoration site have been the subject of several biological studies conducted specifically for this project and historically for other projects, as well as ongoing/continuous studies in the lagoon. These efforts have been driven by different projects, individuals, and/or agencies, and have been conducted at San Dieguito Lagoon W-19 Restoration Project Final BSR Page 5

13 different levels of detail or within different portions of the lagoon. These efforts, in conjunction with a number of focused studies, have been considered in the preliminary planning process for the proposed project, as described in Chapter PROJECT LIMITS AND PURPOSE Project Limits The W-19 restoration site is located on the south side of the San Dieguito River within the San Dieguito River Park. The restoration site is located just upstream from the SCE restoration project limits. The disposal site is located on City-owned land approximately 0.4 mile south of the W-19 site. Off-road temporary access routes would allow travel between the two sites without the use of public roads. A portion of the proposed disposal site is used for materials disposal for the SCE restoration project (DS-36) (Figure 1-2). Maintenance of restored wetland areas within W-19 would also be included in the proposed project. Deposited sediment would be removed from the W-19 site after severe storm events and placed on area beaches adjacent to the lagoon inlet (maintenance placement sites). These beaches are currently used as placement sites for the SCE restoration project inlet maintenance, and are located within the City of Del Mar west of the Del Mar Fairgrounds (Figure 1-2). The proposed project would be incorporated into the overall vision of the restored San Dieguito Lagoon system, including other restoration projects as described below, and the vision of the Park Master Plan, which would be updated as part of the proposed project. The Park Master Plan provides a framework for implementing community goals for the restoration of the San Dieguito Lagoon ecosystem, both tidal and nontidal, and for the provision of public access trails and amenities for public enjoyment and nature study (San Dieguito River Park JPA 2000). The project would restore areas identified in the Park Master Plan (see areas identified as U19, W36, M32, M33, and M37 in the Park Master Plan), as well as other areas west of El Camino Real owned by the City and CDFW (Figures 1-2 and 1-3). The existing recreational trail system in the San Dieguito Lagoon ecosystem would also be expanded as part of the project. The Park Master Plan would be amended to redesignate the restored areas as W-19 and incorporate the updated boundaries of restoration and proposed habitat types associated with the proposed project Purpose of the Proposed Project The purpose of the proposed project is to restore coastal wetlands that can be maintained into the future, which would be used as mitigation for transportation projects within the coastal corridor of north San Diego, partially offsetting wetland losses within the San Dieguito Lagoon system. Page 6 San Dieguito Lagoon W-19 Restoration Project Final BSR

14 *The westernmost parcels are currently owned by the City of San Diego, who has an agreement to sell the land to SANDAG once the W-19 site has received all necessary federal and state permits. SANDAG will transfer the property to the JPA after the site meets its success criteria. San Andres Drive Via de La Valle San Dieguito River San Dieguito Rd. Old El Camino Real!"^$ El Camino Real Source: JPA: Dokken 2015 I 1, ,250 Feet Scale: 1:15,000 1 inch = 1,250 feet San Dieguito Lagoon W-19 Restoration Project Draft BSR Path: P:\2012\ _SD_W19\06GIS\6.3_Layout\Reports\BSR\Ownership.mxd, 2/23/2017, paul.moreno Legend Project Area Disposal Site Temporary Haul Route Ownership City of San Diego SANDAG* San Dieguito River Park Joint Powers Authority (JPA) 22nd District Agricultural Association California Department of Fish and Wildlife SANDAG Technical Services - GIS Figure 1-3 Ownership

15 Accordingly, the primary objectives of the proposed project include: Establish a functional mix of coastal wetlands that includes approximately 50 acres of tidal salt marsh and contribute to the upland mitigation need identified in Table 1 of the Resource Enhancement and Mitigation Plan of the PWP/TREP (Caltrans 2016a). Establish approximately 15 acres of brackish wetlands and 3 acres of riparian habitat, and enhance an additional 2 acres of riparian habitat as identified in the El Camino Real Bridge Replacement Project Recirculated EIR (SCH No ). Enhance connectivity of the San Dieguito River to the river valley to promote functionality of the broader lagoon ecosystem. Promote a sustainable system of native wetland and terrestrial vegetation communities that is resilient against the effects of sea level rise. Promote recreational trail connectivity and enhancement of public access within and adjacent to the San Dieguito River Park and San Dieguito Lagoon. Complement existing restoration efforts (e.g., SCE s restoration project). Maintain coastal littoral zone conditions along the beach/coastline. Maintain or enhance current flood protection, specifically for existing infrastructure and development. The proposed project would restore approximately 141 acres to a functional mix of tidal salt marsh, brackish marsh, and transitional/upland habitats. Tidal salt marsh habitat would be established west of the existing utility corridor and brackish marsh habitat east of the utility corridor. Upland/transitional habitats would be placed adjacent to wetland habitat to support ecological function of the restoration project (Figure 1-4). The existing utility corridor would be enhanced (e.g., through planting with transitional habitat consisting of low-growing, native species that would be maintained by San Diego Gas and Electric [SDG&E]) as part of the proposed project. As part of the proposed project, approximately 60 acres of tidal salt marsh would be established west of the existing utility corridor and south of the river. Tidal connection with the San Dieguito River would be constructed at the west end of the project site in the vicinity of the existing least tern nesting island. A vegetated berm planted with a mix of transitional and upland habitat would be constructed between the salt marsh and the San Dieguito River channel to protect the wetlands from damage due to flood and sedimentation, and to maintain sand movement through the river channel. Figure 1-4 depicts the approximate boundaries of habitat that would be created Page 8 San Dieguito Lagoon W-19 Restoration Project Final BSR

16 San Andres Drive Brackish Marsh Inlet D i eg ui t o Rive r Ca m in o Re al S an Saltwater Marsh Inlet O ld El o Real El Camin LEGEND Project Area Coastal Brackish Marsh Maintenance Road Riparian Enhancement Rock Slope Protection Proposed Trail Existing Trail Proposed Habitat Open Water Mud Flat Low Salt Marsh Mid-High Salt Marsh Riparian Transitional Transitional (Maintained) Coastal Sage Scrub Alkali Marsh Developed Disturbed/Bare Ground Non-native Grassland SANDAG Technical Services - GIS Source: JPA: Dokken 2015 I Scale: 1:4, Feet 1 inch = 400 feet San Dieguito Lagoon W-19 Restoration Project Draft BSR Path: P:\2012\ _SD_W19\06GIS\6.3_Layout\Reports\BSR\Alt_A_Habitats.mxd, 1/9/2017, paul.moreno Figure 1-4 Proposed Habitat Distribution

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18 by the proposed project. Protection from erosion within the site would be provided along the utility corridor as well as at the outlet of the existing stormwater culvert extending under El Camino Real. East of the existing utility corridor, approximately 15 acres of brackish marsh would be established as part of the proposed project, and riparian establishment and enhancement would be completed. An open water channel from the San Dieguito River would be constructed through the brackish marsh area. Similar to the salt marsh area, a vegetated berm planted with coastal sage scrub would be constructed between established brackish marsh habitats and the San Dieguito River channel. The vegetated berm would be designed to protect the wetlands from damage due to flood and sedimentation, and to maintain sand movement to the ocean. Implementation of the proposed project would require relocation of an existing 69-kilovolt electrical line and poles that extend through the W-19 site. The City of San Diego is planning to underground that segment within existing and planned roadways in the future, but if timing requires relocation prior to that planned implementation, the proposed project would coordinate the relocation to incorporate the line along the existing utility corridor, either within the corridor easement or by increasing the easement up to 20 feet, if necessary. The electrical line would then be redirected along El Camino Real west to reconnect with the system extending south of the W-19 site. In this scenario, the City may underground the electrical line as part of the future project. Habitat restoration activities would include excavation of material to lower elevations and opening of the area to tidal and/or river influence. Excavated material and excess sediment removed during restoration would be transported using off-road trucks for disposal on City of San Diego land south of the project (Figure 1-3). The proposed project would also include construction of a new trail adjacent to El Camino Real (Figure 1-4). This new trail would extend north from the existing Dust Devil Nature Trail (previously identified as the Mesa Loop Trail in the Park Master Plan) to provide increased recreational opportunities in the lagoon. In addition, a maintenance road extending west from the utility corridor would be constructed within the vegetated berm to provide access to the salt marsh and existing least tern nesting island. Wetlands Maintenance Deposition of sediment following large storm events would result in a number of changes within the W-19 site, including habitat shifts and mortality of existing plants and infauna (Chris Nordby, personal communication, 2016). Therefore, maintenance of the W-19 inlets would be required after large storm events (25-year event or larger) to remove accumulated deposited San Dieguito Lagoon W-19 Restoration Project Final BSR Page 11

19 material. Large storm events (25-year storm or larger) have the potential to result in measurable sediment accumulation in the salt marsh and brackish marsh inlet connections to the San Dieguito River. Inlet closure could cause the habitat distribution within the restored wetlands to change and would result in reduced circulation and tidal exchange. Therefore, to avoid largescale conversion of habitat and/or water quality issues in restored wetland areas, maintenance to remove accumulated sediment from the inlets of the W-19 salt and brackish marsh after large storm events would be required. The frequency of storm events severe enough to warrant inlet maintenance is highly variable and difficult to predict, and sediment deposition is anticipated to occur primarily during these events rather than steadily accumulate. Therefore, maintenance intervals are unknown and volumes of inlet maintenance (shown in Table 1-1 below) are based on deposition anticipated after specific storm events (25-50-, 100-year). Table 1-1 Anticipated Inlet Maintenance Requirements after Storm Events Storm Frequency Maintenance Area Maintenance Volume (cy) 1 Truck Round Trips (8 cy/trip) Duration (working days) 2 25-year Total 5, Salt Marsh Inlet 1,000 Brackish Marsh Inlet 4, year Total 20,000 2, Salt Marsh Inlet 1,000 Brackish Marsh Inlet 19, year Total 15,000 1, Salt Marsh Inlet 1,000 Brackish Marsh Inlet 14,000 cy = cubic yards, cy/trip = cubic yards per trip 1 Maintenance volumes assume 25 percent of deposited material would remain in place and would not be removed. 2 Activities on the beach would be 2 days less than overall maintenance activities; rates for removal/transport are assumed to be 500 cy per day, working 10 hours per day. Mobilization and demobilization and construction of temporary access roads would require an additional 3 days. Vegetation may be temporarily impacted from sedimentation and/or maintenance activities within the areas but would be anticipated to recover over time. The following criteria would be utilized to determine when sediment maintenance would be required: If sediment delivered by a storm is blocking tidal flows to wetlands, If sediment has created stagnant areas, and/or If 6 or more inches of sediment is deposited in wetlands designated for adaptive management and replanting on top of the sediment would not support the habitat type present just before the storm event. Material removed from the W-19 site during maintenance is anticipated to be suitable for placement on the nearby beach. It is anticipated that material removed from the W-19 site during Page 12 San Dieguito Lagoon W-19 Restoration Project Final BSR

20 maintenance would be suitable for reuse and would be transported by trucks to nearby beaches for placement/disposal. The placement sites and placement approach would be the same as those currently used for maintenance dredging of the San Dieguito River inlet as part of the SCE restoration project, which includes material being transported by trucks, placed on the beach, and spread by bulldozers. These sites are shown in Figure 1-5. Portions of the restored wetlands beyond the designated inlet maintenance areas could also experience sediment deposition following 50-year or larger storm events. Figure 1-6 shows the areas that modeling suggests would require maintenance after these events. However, because the precise location of this deposition is difficult to predict, analysis would be conducted following storms of this severity to identify deposition areas and depths. The same criteria that would trigger inlet maintenance, as described for W-19 inlet maintenance earlier in this section, would be applied to determine if sediment maintenance is necessary. Overall volumes of sediment anticipated to be removed under 50- and 100-year storms are shown in Table 1-2. Table 1-2 Anticipated Interior Wetland Sediment Maintenance Required Storm Frequency Maintenance Volume (cy) 1 Truck Round Trips (8 cy/trip) 50-year 10,000 1, year 45,000 5, Duration (working days) 2 cy = cubic yards, cy/trip = cubic yards per trip 1 Maintenance volumes assume 25 percent of deposited material would remain in place and would not be removed. 2 Activities on the beach would be 2 days less than overall maintenance activities; rates for removal/transport are assumed to be 500 cy per day, working 10 hours per day. Mobilization and demobilization and construction of temporary access roads would require an additional 3 days Project Alternatives Two alternatives to the proposed project have been identified for the restoration site. Alternative B Alternative C Two alternatives to the proposed project are also being evaluated for the salt marsh portion of the site, including an alternative that would allow large flood flows down the San Dieguito River into the established salt marsh area (Alternative B, Figure 1-7), and an alternative that would establish two tidal salt marsh channel systems (Alternative C, Figure 1-8) separated by a vegetated berm. Alternatives to the brackish marsh area east of the utility corridor are also being considered, including an alternative that would allow flood flows into the brackish marsh (Alternative B). San Dieguito Lagoon W-19 Restoration Project Final BSR Page 13

21 Each of the alternatives to the proposed project would restore approximately 75 to 85 acres to a functional mix of tidal salt marsh and brackish marsh. Similar to the proposed project, the alternatives would establish tidal salt marsh habitat west of the existing utility corridor and brackish marsh habitat east of the utility corridor. Upland/transitional habitats would also be established adjacent to wetland to provide a gradient of habitat types Alternative B Under Alternative B, the habitat distribution would be very similar to that under the proposed project. This alternative would create a lower elevation separation between the river and established wetland than under the proposed project, allowing storm flows from the river to flow into the wetland areas more frequently than under the proposed project. Development of this alternative was a result of early coordination with wildlife and regulatory agencies that expressed a desire to see a more naturally functioning wetland system that could be influenced by episodic sedimentation and evolve over time. Approximately 60 acres of tidal salt marsh would be established west of the existing utility corridor, with a western tidal connection to the San Dieguito River south of the existing least tern nesting island. The proposed vegetated berm would be planted with a mix of transitional and coastal scrub species, but the elevation of the upland berm would be much lower than that identified for the proposed project. Rather than an ultimate elevation of 20 feet, under Alternative B the vegetated berm would have an elevation of approximately 10 feet and be overtopped during a 25-year or larger storm event. This alternative would therefore be influenced by both tidal exchange and upstream river (fluvial) processes. This differs from the proposed project, which would create a system primarily influenced by tidal exchange and would remain protected from fluvial processes by a berm (e.g., sedimentation or channel migration) from up to a 50-year flood event. Figure 1-7 depicts the approximate boundaries of habitat that would be created under Alternative B. Similar to the proposed project, protection from erosion within the site would be provided along the utility corridor, as well as at the outlet of the existing stormwater culvert extending under El Camino Real. Under Alternative B, the existing utility corridor would also be enhanced (e.g., through planting with transitional habitat to be maintained by SDG&E) as described for the proposed project. East of the existing utility corridor, approximately 15 acres of brackish marsh would be established as part of Alternative B. Similar to the proposed project, an open water channel from the San Dieguito River would be constructed through the brackish marsh area. A vegetated berm would be created between the brackish marsh habitat and the San Dieguito River channel at an elevation of 8 to 11 feet; much lower than the 22-foot elevation berm under the proposed project, and it is anticipated that this lower berm would be overtopped during a 10-year or greater storm. Page 14 San Dieguito Lagoon W-19 Restoration Project Final BSR

22 Via de La Valle San Andres Drive Birdwing Open Air Classroom Del Mar Horse Park San Diego Polo Fields Þ Camino del Mar Fairbanks Ranch Golf Course Railroad Del Mar Fairgrounds San Dieguito Road Jimmy Durante Blvd!"^$ El Camino Real Old El Camino Real Þ LEGEND Project Area Material Placement (Post-Storm Event) Sediment Haul Route Proposed Habitat Open Water Mud Flat Low Salt Marsh Mid-High Salt Marsh Riparian Scrub Riparian Enhancement Transitional Transitional (Maintained) Coastal Sage Scrub Alkali Marsh Developed Disturbed/Bare Ground Non-native Grassland Coastal Brackish Marsh Source: JPA: Dokken 2015 I 1, ,000 Feet Scale: 1:12,000; 1 inch = 1,000 feet San Dieguito Lagoon W-19 Restoration Project Draft BSR Path: P:\2012\ _SD_W19\06GIS\6.3_Layout\Reports\BSR\Wetlands_Maintenance.mxd, 1/10/2017, paul.moreno Figure 1-5 Wetlands Maintenance and Material Placement

23 San Andres Drive San Dieguito River El Camino Real Old El Camino Real Source: SANDAG 2014: Dokken I Feet Scale: 1:4,800 1 inch = 400 feet San Dieguito Lagoon W-19 Restoration Project Draft BSR Path: P:\2012\ _SD_W19\06GIS\6.3_Layout\Reports\BSR\Wetlands_Maintenance_Areas A.mxd, 1/10/2017, paul.moreno Project Area Inlet Maintenance (25-Year & Greater Storm) Anticipated Areas Requiring Sediment Removal (50-Year & Greater Storm) Proposed Habitat Open Water Mud Flat Low Salt Marsh LEGEND Mid-High Salt Marsh Coastal Brackish Marsh Riparian Riparian Enhancement Transitional Transitional (Maintained) Coastal Sage Scrub Developed/Maintenance Road Disturbed/Bare Ground Non-native Grassland SANDAG Technical Services - GIS Figure 1-6 Proposed Project Wetland Maintenance Areas

24 San Andres Drive Brackish Marsh Inlet San Dieguito River Saltwater Marsh Inlet Source: JPA: Dokken 2015 I Feet Scale: 1:4,800 1 inch = 400 feet San Dieguito Lagoon W-19 Restoration Project Draft BSR Path: P:\2012\ _SD_W19\06GIS\6.3_Layout\Reports\BSR\Alt_B_Habitats.mxd, 1/10/2017, paul.moreno El Camino Real Project Area Rock Slope Protection Maintenance Road Proposed Trail Existing Trail Inlet Maintenance Areas Proposed Habitat Open Water Mud Flat Low Salt Marsh Mid-High Salt Marsh Coastal Brackish Marsh Riparian Scrub LEGEND Old El Camino Real Riparian Enhancement Coastal Sage Scrub Transitional Transitional (Maintained) Alkali Marsh Developed Disturbed/Bare Ground Non-native Grassland SANDAG Technical Services - GIS Figure 1-7 Alternative B - Habitat Distribution

25 San Andres Drive Brackish Marsh Inlet guito R iver C am in o R ea l San Die LEGEND O ld Saltwater Marsh Inlet El o Real El Camin Project Area Coastal Brackish Marsh Proposed Trail Riparian Enhancement Maintenance Road Existing Trail Rock Slope Protection Inlet Maintenance Areas Anticipated Areas Requiring Sediment Removal after 50-Year or Greater Storm Proposed Habitat Open Water Riparian Coastal Sage Scrub Transitional Transitional (Maintained) Alkali Marsh Developed Disturbed/Bare Ground Non-native Grassland Mud Flat Low Salt Marsh Mid-High Salt Marsh SANDAG Technical Services - GIS Source: JPA: Dokken 2015 I Scale: 1:4, Feet 1 inch = 400 feet San Dieguito Lagoon W-19 Restoration Project Draft BSR Path: P:\2012\ _SD_W19\06GIS\6.3_Layout\Reports\BSR\Alt_C_Habitats.mxd, 1/11/2017, paul.moreno Figure 1-8 Alternative C - Habitat Distribution

26 The existing 69-kilovolt electrical line and poles that extend through the W-19 site would be relocated as part of Alternative B, as described for the proposed project, and habitat restoration activities would include excavation of material to lower elevations and open the area to tidal and/or river influence. Excavated material and excess sediment removed during restoration would be transported for disposal, as described for the proposed project. Construction of a new trail adjacent to El Camino Real extending north from the existing Dust Devil Nature Trail (previously identified as the Mesa Loop Trail) to provide increased recreational opportunities in the lagoon would be included as part of Alternative B. In addition, a maintenance road extending west from the utility corridor along the vegetated berm would be constructed to provide access to the salt marsh and existing least tern nesting island. Wetlands Maintenance As described under the proposed project, hydrologic modeling predicted that large storm events (25-year or greater events) would have the potential to result in sediment accumulation, particularly in the salt marsh and brackish marsh inlets. Inlet maintenance would therefore be required after 25-year or larger storm events to remove sediment deposited in wetland inlet areas. Areas that would require maintenance after large storm events under Alternative B are shown in Figure 1-7. Wetlands inlet maintenance methods described for the proposed project would also be used under Alternative B. Anticipated volumes of material removed after a range of storm events, as well as the corresponding duration and truck trips, is described in Table 1-3. Table 1-3 Alternative B Anticipated Inlet Maintenance Requirements after Storm Events Alternative B Maintenance Volume (cy) 1 Storm Frequency Maintenance Area Truck Round Trips (8 cy/trip) 25-year Total 2, Salt Marsh Inlet 1,000 Brackish Marsh Inlet 1, year Total 15,000 1, Salt Marsh Inlet 1,000 Brackish Marsh Inlet 14, year Total 20,000 2, Salt Marsh Inlet 1,000 Brackish Marsh Inlet 19,000 cy = cubic yards, cy/trip = cubic yards per trip 1 Maintenance volumes assume 25 percent of deposited material would remain in place and would not be removed. 2 Duration (working days) 2 Activities on the beach would be 2 days less than overall maintenance activities; rates for removal/transport are assumed to be 500 cy per day, working 10 hours per day. Mobilization and demobilization and construction of temporary access roads would require an additional 3 days. San Dieguito Lagoon W-19 Restoration Project Final BSR Page 19

27 The design of Alternative B was influenced by resource agency input to allow the wetland/upland habitat distribution to evolve over time based on river dynamics. Therefore, Alternative B does not include protective berms between the active low flow river channel and the restored wetland areas. As a result, river flows would enter restored wetland areas under smaller/more frequent storm events than under the proposed project. This would result in larger volumes of sediment deposited within the site, including in areas of sensitive habitat. Unlike under the proposed project, adaptive management to maintain appropriate elevations for specific habitats within the interior portions of the wetland would not be conducted under Alternative B. Instead, the site would evolve as sediment continues to deposit within the site. Inlet maintenance would be conducted under this alternative to ensure continued tidal exchange and prevent water quality concerns and human health hazards from developing Alternative C Under Alternative C (Figure 1-8), the habitat distribution would consist of two separate tidal channel systems, one directly adjacent to the San Dieguito River, and one separated from the river by a vegetated berm. A deliberate design feature of Alternative C includes restoration of salt marsh adjacent to the active low flow river channel, which would allow the salt marsh to be directly influenced by river dynamics and evolve over time. The purpose of this design is to allow the natural dynamics of the river to dictate the site and modify elevations and habitats naturally over time. To allow this evolution, adaptive management to maintain habitat would not be conducted within the portion of the wetland adjacent to the river under Alternative C. Approximately 70 acres of tidal salt marsh would be established west of the existing utility corridor, with approximately one-third of that (22 acres) located adjacent to the river and twothirds (47 acres) protected by the vegetated berm. The protected portion of the site would have a western tidal connection to the San Dieguito River south of the existing least tern nesting island. The portion of the site adjacent to the river would connect to the river east of the nesting site, but would be anticipated to evolve from wetlands to transitional and upland over time as storm flows from the river deposit river sediment on the site. The proposed vegetated area would be planted with a mix of transitional and coastal scrub species, and would be at an elevation of 20 feet, similar to that identified for the proposed project. Alternative C would provide systems representative of both the proposed project and Alternative B; the area protected by the vegetated berm would be primarily tidally influenced, similar to the proposed project, while the area adjacent to the river would be initially influenced both by tidal and fluvial processes, but, after major storms of 25-year or greater frequency, the unprotected wetlands area would be filled with river sediment. Figure 1-8 depicts the approximate boundaries of habitat that would be created under Alternative C. Similar to the proposed project, protection from erosion within the site would be provided along the utility corridor, as well as at the outlet of the existing stormwater culvert extending under El Camino Real. Under Alternative C, the existing utility corridor would Page 20 San Dieguito Lagoon W-19 Restoration Project Final BSR

28 also be enhanced (e.g., through planting with transitional habitat to be maintained by SDG&E) as described for the proposed project. East of the existing utility corridor, the brackish portion of the site would be established as discussed under the proposed project. Approximately 15 acres of brackish marsh would be established as part of Alternative C, with an open water channel through the site. Similar to the salt marsh area, a vegetated berm planted with coastal sage scrub would be constructed at an elevation of approximately 22 feet between established brackish marsh habitats and the San Dieguito River channel. The vegetated berm would protect the wetlands from damage due to flood and sedimentation, and would maintain sand movement to the ocean. The existing 69-kilovolt electrical line and poles that extend through the W-19 site would be relocated as part of Alternative C, as described for the proposed project, and habitat restoration activities would include excavation of material to lower elevations and would open the area to tidal and/or river influence. Excavated material and excess sediment removed during restoration would be transported for disposal onsite, as described for the proposed project. Construction of a new trail adjacent to El Camino Real extending north from the existing Dust Devil Nature Trail (previously identified as the Mesa Loop Trail) to provide increased recreational opportunities in the lagoon would be included as part of Alternative C. In addition, a maintenance road extending west from the utility corridor along the vegetated berm would be constructed to provide access to salt marsh and the existing least tern nesting island. Wetlands Maintenance Hydraulic modeling predicts that sedimentation would occur under Alternative C, as discussed for the proposed project, and inlet maintenance would be required. Similar to the proposed project, inlet maintenance would be required after large storm events (25-year event or greater) to remove accumulated sediment from the restored inlet connections within the site. Areas that would require maintenance after large storm events under Alternative C are shown in Figure 1-8. Under this alternative, the same criteria described under the proposed project would trigger sediment maintenance. Anticipated volumes of material removed after a range of storm events, as well as the corresponding duration and truck trips, are described in Table 1-4. Under this alternative, sedimentation would occur at a much higher rate in the portion of tidal wetlands located directly adjacent to the San Dieguito River. After severe storm events, sediment accumulation would bury most of the portion of the site directly adjacent to the river, and other areas of the site would be eroded as a new river channel develops. Maintenance within the portion of the wetland adjacent to the river would not occur under this alternative in order to allow the site to evolve based on river dynamics. San Dieguito Lagoon W-19 Restoration Project Final BSR Page 21

29 Table 1-4 Alternative C Anticipated Inlet Maintenance Requirements after Storm Events Storm Frequency Maintenance Area Alternative C Maintenance Volume (cy) 1 Truck Round Trips (8 cy/trip) Duration (working days) 2 25-year Total 6, days Salt Marsh Inlet 1,000 Brackish Marsh Inlet 5, year Total 20,000 2, days Salt Marsh Inlet 2,000 Brackish Marsh Inlet 18, year Total 10,000 1, days Salt Marsh Inlet 2,000 Brackish Marsh Inlet 8,000 cy = cubic yards, cy/trip = cubic yards per trip 1 Maintenance volumes assume 25 percent of deposited material would remain in place and would not be removed. 2 Activities on the beach would be 2 days less than overall maintenance activities; rates for removal/transport are assumed to be 500 cy per day, working 10 hours per day. Mobilization and demobilization and construction of temporary access roads would require an additional 3 days. Established wetlands beyond the designated inlet maintenance areas and the river-adjacent wetland could also experience sediment deposition following 50-year or larger storm events. Figure 1-8 shows the anticipated areas that modeling suggests would require maintenance after these events. However, because the precise location of this deposition is difficult to predict, field monitoring and analysis would be conducted following storms of this severity to identify deposition areas and depths. The same criteria that would trigger inlet maintenance, as described for W-19 inlet maintenance earlier in this section, would be applied to determine if sediment maintenance is necessary. Overall volumes of sediment anticipated to be removed under 50- and 100-year storms are shown in Table 1-5. Table 1-5 Anticipated Interior Wetland Sediment Maintenance Required Storm Frequency Maintenance Volume (cy) 1 Truck Round Trips (8 cy/trip) Duration (working days) 2 50-year 5, year 20,000 2, cy = cubic yards, cy/trip = cubic yards per trip 1 Maintenance volumes assume 25% of deposited material would remain in place and would not be removed. 2 Activities on the beach would be 2 days less than overall maintenance activities; rates for removal/transport are assumed to be 500 cy per day, working 10 hours per day. Mobilization and demobilization and construction of temporary access roads would require an additional 3 days. Page 22 San Dieguito Lagoon W-19 Restoration Project Final BSR

30 CHAPTER 2.0 METHODS 2.1 BIOLOGICAL STUDY AREA The Biological Study Area (BSA) encompasses the potential impact footprint of the project, as well as a 100-foot buffer. The potential impact footprint for the proposed project and the two alternatives is contained within the same boundaries, and therefore the BSA encompasses one area applicable to all alternatives. The BSA is divided into four areas: W-19 restoration site, disposal site, haul route between the two sites, and maintenance material placement site (Figure 2-1). The W-19 restoration site is bounded by the San Dieguito River to the north, El Camino Real to the east and south, and the SCE restoration project site to the west. The disposal site is located west of El Camino Real and east of I-5, and portions have been previously cleared and graded. These specific areas that constitute the BSA are summarized in Table 2-1, including the general location and approximate acreage of each area. Table 2-1 BSA Acreages by Area Area (includes associated 100-foot buffer) General Location Acreage W-19 Restoration Site Between El Camino Real and the San Dieguito River 179 Disposal Site West of El Camino Real, south of W Haul Route North-south linkage between W-19 and the disposal site 19 Maintenance Material Placement Site Beaches west of San Dieguito Lagoon 30 TOTAL BIOLOGICAL FIELD SURVEYS AND DATA SOURCES Biological field surveys completed for this project include vegetation mapping, special-status plant surveys, special-status wildlife surveys, and a jurisdictional wetlands delineation, each conducted 2011 through The surveys were conducted by various consultants including AECOM, Nordby Biological Consulting, Konecny Biological Services, and agencies such as Caltrans. The subjects of these surveys, their location and year, and the surveyors are listed in Table 2-2 below. San Dieguito Lagoon W-19 Restoration Project Final BSR Page 23

31 Path: P:\2012\ _SD_W19\06GIS\6.3_Layout\Reports\BTR\BSA.mxd, 10/20/2016, paul.moreno San Dieguito Lagoon W-19 Restoration Project Draft BSR San Dieguito River Via de La Valle!"^$ GF! El Camino Real GF! Old El Camino Real LEGEND GF! Project Area Disposal Site Temporary Haul Route 100ft Buffer - BSA Temporary Construction Entrance Source: Dokken 2015; AECOM; SANDAG I 1, ,250 Feet Scale: 1:15,000 1 inch = 1,250 feet Figure 2-1 Biological Study Area