APPENDIX C LAKE WOHLFORD DAM REPLACEMENT PROJECT BIOLOGICAL TECHNICAL REPORT Lake Wohlford Dam Replacement Project EIR Appendices BIOLOGICAL TECHNICAL REPORT FOR THE LAKE WOHLFORD DAM REPLACEMENT PROJECT Prepared for: City of Escondido Utilities Department 201 North Broadway Escondido, California 92025 Prepared by: AECOM 401 West A Street, Suite 1200 San Diego, California 92101 (619) 610-7600 Contact: Lyndon Quon August 2015 TABLE OF CONTENTS Section Page EXECUTIVE SUMMARY .............................................................................................................v CHAPTER 1.0 – INTRODUCTION ...............................................................................................1 1.1 Purpose of Study and Project Background ............................................................. 1 1.2 Project Description.................................................................................................. 5 1.2.1 Project Location ..........................................................................................5 1.2.2 Project Purpose ............................................................................................5 1.2.3 Project Description ......................................................................................5 CHAPTER 2.0 – METHODS ........................................................................................................13 2.1 Biological Study Area ........................................................................................... 13 2.2 Biological Field Surveys ....................................................................................... 13 2.2.1 Vegetation Mapping ..................................................................................14 2.2.2 Jurisdictional Waters and Wetlands Delineation Surveys.........................15 2.2.3 Sensitive Plant Surveys .............................................................................16 2.2.4 General Wildlife Surveys ..........................................................................17 2.2.5 Coastal California Gnatcatcher Surveys ...................................................17 2.2.6 Least Bell’s Vireo Surveys ........................................................................17 2.2.7 Southwestern Willow Flycatcher Surveys ................................................18 2.2.8 Bat Surveys ...............................................................................................18 2.3 Personnel and Survey Dates.................................................................................. 18 2.4 Agency Coordination ............................................................................................ 18 CHAPTER 3.0 – EXISTING CONDITIONS ...............................................................................19 3.1 Vegetation Communities ...................................................................................... 19 3.1.1 Riparian and Wetland Vegetation Communities .......................................20 3.1.2 Upland Vegetation Communities ..............................................................27 3.1.3 Other Cover Types ....................................................................................30 3.2 Jurisdictional Waters and Wetlands ...................................................................... 30 3.3 Flora ...................................................................................................................... 34 3.3.1 Sensitive Plant Species ..............................................................................48 3.4 Wildlife ................................................................................................................. 48 3.5 Wildlife Movement ............................................................................................... 63 Lake Wohlford Dam Replacement Project Biological Technical Report Page i CHAPTER 4.0 – IMPACT ANALYSIS .......................................................................................65 4.1 Vegetation Communities ...................................................................................... 69 4.2 Jurisdictional Waters ............................................................................................. 71 4.3 Sensitive Plants ..................................................................................................... 73 4.4 Sensitive Wildlife.................................................................................................. 74 4.5 Migratory Birds ..................................................................................................... 75 4.6 Wildlife Movement ............................................................................................... 76 CHAPTER 5.0 – RECOMMENDED MITIGATION MEASURES .............................................77 CHAPTER 6.0 – REFERENCES ..................................................................................................83 APPENDICES A 45-Day Report for Coastal California Gnatcatcher B 45-Day Report for Least Bell’s Vireo C 45-Day Report for Southwestern Willow Flycatcher D Bat Surveys and Habitat Assessment Report E List of Survey Personnel and Dates of Surveys F List of Plant Species Observed in BSA G List of Wildlife Species Observed in BSA Page ii Lake Wohlford Dam Replacement Project Biological Technical Report LIST OF FIGURES Figure Page 1 Regional Map .......................................................................................................................2 2 Project Vicinity ....................................................................................................................4 3a Biological Study Area ..........................................................................................................7 3b Limits of Disturbance (LOD) and Buffer ............................................................................9 3c Proposed Reservoir Level and Biological Study Area ......................................................11 4 CNDDB Species Inventory ................................................................................................21 5 Vegetation Communities ...................................................................................................23 6 Jurisdictional Waters ..........................................................................................................31 7 Sensitive Plants (Quercus engelmannii) ............................................................................49 8 Wildlife Survey Areas and Special Status Species Observations ......................................61 9 Direct and Indirect Impact Areas Associated with Limits of Disturbance ........................67 LIST OF TABLES Table Page ES-1 Mitigation for Direct Impacts to Sensitive Vegetation Communities (acres)................... vii 1 Vegetation Communities and Cover Types within the LOD and Maximum Inundation Area .................................................................................................................20 2 Delineated Waters of the U.S. and State ............................................................................33 3 Summary of Delineated Waters of the U.S. and State .......................................................33 4 Listed and Proposed Plant Species Potentially Occurring or Known to Occur in the Lake Wohlford Dam Replacement Project Biological Study Area .............................35 5 Sensitive Wildlife Species with Potential to Occur within the Biological Study Area .........................................................................................................................51 6 Direct Impacts to Vegetation Communities and Cover Types within the Limits of Disturbance ....................................................................................................................70 7 Impacts to Waters of the U.S. and State ............................................................................72 8 Mitigation for Permanent Direct Impacts to Sensitive Vegetation Communities (acres) .................................................................................................................................77 Lake Wohlford Dam Replacement Project Biological Technical Report Page iii This page intentionally left blank. Page iv Lake Wohlford Dam Replacement Project Biological Technical Report EXECUTIVE SUMMARY The City of Escondido (City) is planning to construct a replacement for Lake Wohlford Dam. A 2007 seismic analysis of the dam identified a stability concern for the raised portion of the dam in the event of a major earthquake. As a result, the City reduced the reservoir’s water level to limit the risk of a potential failure. The water level reduction decreased the reservoir’s capacity to approximately 40% of its prior size. To improve the dam’s seismic safety and regain the lost water storage capability, the City is planning to construct a replacement dam downstream (west) of the existing dam and partially or completely deconstruct the existing dam. Replacing the dam would require replacement or modification of the existing dam’s outlet tower and associated pipes beneath the dam. To accommodate the replacement dam’s configuration, the project would also entail realignment of the portion of Oakvale Road that passes the southern dam abutment. This portion of the road would be realigned south of its current location, requiring excavation into the adjacent hillside. The project would allow