Wetlands and Water Resources, Inc 818 5th Avenue, Suite 208 San Rafael, California 94901 tel 415.457.0250 fax 415.457.0260 www.swampthing.org Pilarcitos Lagoon Habitat Enhancement Feasibility Study: Final Report 11 May 2010 Prepared for: San Mateo County Resource Conservation District 625 Miramontes Street Suite 103, Half Moon Bay, California 94019 www.sanmateorcd.org With: Peter Baye, PhD D.W. Alley and Associates Project No. 1148 Planning Assessment Design Implementation Applied Science Pilarcitos Lagoon Habitat Enhancement Feasibility Study Final Report – May 11, 2010 Table of Contents Acknowledgements ....................................................................................................................... 1 1 Introduction ........................................................................................................................... 2 1.1 Goals and Objectives ........................................................................................................ 3 1.2 Project Process ................................................................................................................. 4 1.3 Terminology ..................................................................................................................... 5 2 Summary of Conceptual Model ........................................................................................... 7 3 Evaluation Criteria ................................................................................................................ 9 3.1 Criterion 1: Benefits to Target Species ........................................................................... 10 3.2 Criterion 2: Implementation Costs ................................................................................. 10 3.3 Criterion 3: Regulatory Requirements ........................................................................... 11 3.4 Criterion 4: Probability of Securing Funding for Implementation ................................. 11 3.5 Criterion 5: Life Expectancy without Operations and Maintenance .............................. 11 3.6 Criterion 6: Intensity and Cost of Operations and Maintenance ................................... 11 3.7 Criterion 7: Interactions with Other Habitat Enhancement Efforts ............................... 11 3.8 Criterion 8: Level of Community/Stakeholder Project Support ..................................... 12 3.9 Criterion 9: Potential Unintended Consequences ......................................................... 12 3.10 Criterion 10: Costs and Benefits Relative to Actions above Highway 1 ..................... 13 3.11 Criterion 11: Extent Option “Works with Nature” ..................................................... 13 4 Enhancement Options ........................................................................................................ 13 4.1 Option 1: Improve Backwater Slough Habitat for Steelhead ......................................... 16 4.1.1 Existing Wetland Environment ............................................................................... 16 4.1.2 Goals and Objectives ............................................................................................... 17 4.1.3 Approach Options ................................................................................................... 18 4.1.4 Opportunities and Constraints ............................................................................... 19 4.1.5 Feasibility Evaluation .............................................................................................. 21 4.2 Option 2: Flow Manipulations in Pilarcitos Creek .......................................................... 23 4.2.1 Setting ..................................................................................................................... 24 4.2.2 Goals and Objectives ............................................................................................... 26 4.2.3 Approach ................................................................................................................. 27 4.2.4 Opportunities and Constraints ............................................................................... 33 4.2.5 Feasibility Evaluation .............................................................................................. 34 4.3 Option 3: Create Scour Pools in Lower Channel ............................................................ 38 4.3.1 Goals and Objectives ............................................................................................... 39 4.3.2 Approach ................................................................................................................. 39 Pilarcitos enhancement feasibility report final_2010‐0511ct 5/11/2010 i Pilarcitos Lagoon Habitat Enhancement Feasibility Study Final Report – May 11, 2010 4.3.3 Opportunities and Constraints ............................................................................... 39 4.3.4 Feasibility Evaluation .............................................................................................. 41 4.4 Option 4: Limit Northward Drift of Beach Outlet .......................................................... 43 4.4.1 Existing Berm and Backbeach Channel Environment ............................................. 43 4.4.2 Goals and Objectives ............................................................................................... 44 4.4.3 Approach and Design Options ................................................................................ 44 4.4.4 Feasibility Evaluation .............................................................................................. 53 4.5 Option 5: Improve Equestrian Crossing ......................................................................... 57 4.5.1 Existing Conditions .................................................................................................. 57 4.5.2 Goals and Objectives ............................................................................................... 58 4.5.3 Approaches, Opportunities and Constraints .......................................................... 59 4.5.4 Feasibility Evaluation .............................................................................................. 62 5 Conclusions and Next Steps .............................................................................................. 65 6 References ........................................................................................................................... 66 List of Tables Table 1. Summary of Enhancement Options Table 2. Pilarcitos Creek Lagoon Closures, WY2003‐2009 List of Figures Figure 1. Vicinity Map Figure 2. Location Map Figure 3. Annotated Historic Aerial Photographs Figure 4. US Coast Survey Maps, 1860 and 1863 Figure 5. Digital Elevation Model Figure 6. Conceptual Deflection Structure Design Figure 7. Conceptual Deflection Berm Design List of Appendices Appendix A Conceptual Model Appendix B Results of Vascular Plant Surveys at the Pilarcitos Creek Mouth Pilarcitos enhancement feasibility report final_2010‐0511ct 5/11/2010 ii Pilarcitos Lagoon Habitat Enhancement Feasibility Study Final Report – May 11, 2010 Acknowledgements The project team has thoroughly enjoyed working on the Pilarcitos Lagoon Habitat Enhancement Feasibility Study and having an opportunity to contribute to the body of knowledge of coastal lagoon ecosystems along California’s Central Coast. We are especially grateful for the support and collaboration of our client, the San Mateo County Resource Conservation District, whose project efforts were capably led by Executive Director Kellyx Nelson. We are grateful for the rigorous scientific review and collaboration provided by the project’s Technical Advisory Committee, which consisted of the following individuals: Tim Frahm, San Mateo County Farm Bureau Jim Howard, Natural Resource Conservation Service Joanne Kerbavaz, California Department of Parks and Recreation Jane Lavelle, San Francisco Public Utilities Commission George Neillands, California Department of Fish and Game Patrick Rutten, National Marine Fisheries Service Jim Salerno, San Francisco Public Utilities Commission Lori Schectel, San Francisco Public Utilities Commission Dan Sicular, ESA A number of additional individuals provided valuable assistance with scientific/policy review and collaboration, including: Cathleen Brennan, Coastside County Water District Kit Crump, National Marine Fisheries Service John Klochak, US Fish and Wildlife Service Tim Ramirez, San Francisco Public Utilities Commission We would also like to thank the many people who contributed personal knowledge of Pilarcitos Creek, its history, and its environs, including Keith Mangold, June Morrall, John and Kristina Schmale, and John Vonderlin. The input provided by these individuals provided important insights into how past activities within and around the creek may have impacted historic and existing conditions. We would also like to thank Shannon Lyday at the Gulf of the Farallones National Marine Sanctuary BeachWatch program and Asha Kreilling, an intern at the San Mateo County Resource Conservation District, who provided valuable data about opening and closing patterns at the outlets of Pilarcitos and Frenchman’s Creeks. We also appreciate the efforts of Meredith Manning and Casey Cleve at the Midpeninsula Regional Open Space District, who provided valuable processed LiDAR data for the Project vicinity. Finally, it is important to note