The Estero Americano Watershed Management Plan A Project of the Gold Ridge Resource Conservation District with funding from the State Water Resources Control Board The Estero Americano Watershed Management Plan Version 1, February 2007 Prepared by: The Gold Ridge Resource Conservation District Patricia Hickey, Project Director Lisa Hulette, Executive Director Joe Pozzi, District Manager Brittany Heck, Natural Resources Coordinator This project was funded in part by a grant from the U.S. Environmental Protection Agency, administered through the State Water Resources Control Board SWRCB Contract No. 03-138-250-1 Other funders of this document include: The State Coastal Conservancy and USDA, Natural Resources Conservation Service Watershed Management Plan Author Patricia Hickey, Project Director Gold Ridge Resource Conservation District P.O. Box 1064 Occidental, CA 95465 Correspondence E-mails: [email protected] or [email protected] RCD Website: http://www.goldridgercd.org Editorial Assistance Lisa Hulette, Executive Director Gold Ridge Resource Conservation District Lauren Hammack, Geomorphologist Prunuske Chatham, Inc. P.O. Box 828 Occidental, CA 95465 Acknowledgements: We thank the Estero Americano Watershed Technical Advisory Committee: Nancy Scolari, Marin Resource Conservation District; Janet Blake, North Coast Regional Water Quality Control Board; Charlette Epifanio, USDA, NRCS; Bill Cox, California Department of Fish & Game; Tom Yarish, Friends of the Esteros; Stephanie Larson, UC Cooperative Extension; Bob Neale, Sonoma Land Trust; Leslie Dapo, Western United Dairymen; Joe Mortenson, Gulf of the Farallones National Marine Sanctuary; and Susan Starbird to name a few. ESTERO AMERICANO WATERSHED MANAGEMENT PLAN – VERSION 1, FEBRUARY 2007 i Table of Contents Executive Summary……………………………………………………...vi Chapter 1. Introduction…………………………………………………1 Chapter 2. Ecological Resources of the Estero Americano Watershed……………………………7 Chapter 3. Water Quality: An Indicator of Watershed Health…..29 Chapter 4. Sediment: Sources and Impacts……………………….44 Chapter 5. Agricultural Best Management Practices…………….58 Chapter 6. Action Plan to Improve Natural Resources and Agricultural Sustainability………………………………74 Literature Cited…………………………………………………………………99 Appendix A: Biological Data…………………………………………104 Appendix B: Water Quality Monitoring Data, 1988-1990…………113 Appendix C: Watershed Modeling Methods and Results…………130 Appendix D: Riparian Assessment………………………………….140 Appendix E: Fisheries Enhancement Report………………………147 Appendix F: Monitoring Needs and Guidelines……………………152 ESTERO AMERICANO WATERSHED MANAGEMENT PLAN – VERSION 1, FEBRUARY 2007 ii Tables, Figures and Charts Table 1-1. Estero Americano Watershed Management Plan Goals & ……………..5 Objectives. Table 2-1. Estuarine Wetland Habitats. ……………..9 Table 2-2. Total Catch in Otter Trawls in the Estero Americano, 1988-1989. ……………15 Table 2-3. Total Catch in Gill Nets in the Estero Americano, 1988-1989. ……………16 Table 2-4. Estero Americano Waterfowl and Shorebird Species List, 1988-1989. ……………19 Table 2-5. Terrestrial Vegetation, LCMMP GIS Data. …………….21 Table 2-6. Estero Americano Terrestrial Birds, Species List 1988- …………….25 1989. Table 3-1. Summary of Potential Pollutants and Sources in the Estero Americano Watershed. …………….31 Table 3-2. Estimated Nutrient Loads (lbs/yr). …………….40 Table 4-1. The predominant soils in the Estero Americano watershed, the characteristics that effect erosion potential, and their distribution throughout the watershed. …………….46 Table 4-2. Summary of sediment loading calculation results. …………….49 Table 4-3. Distribution of aerial-photo mapped gullies in the watershed. …………….54 Table 5-1. Existing Conservation Programs in the Estero Americano Watershed. ……………59 Table 5-2. Management Objectives, Indicators and Target Values. ……………60 Table 5-3. Estimated Load Reductions from Currently Funded RCD Grant Programs, 2006-2010. …………...72 Table 6-1. Implementation goals, desired outcomes, milestones and indicators. …………...95 ESTERO AMERICANO WATERSHED MANAGEMENT PLAN – VERSION 1, FEBRUARY 2007 iii Figure 1-1. Map of RCD boundaries …………….1 Figure 2-1. Estero Americano Wetlands and Estuary Sampling Stations, 1988-1989. …………….8 Figure 2-2. Important Wetlands and Beaches of Sonoma and Marin Counties. ……………18 Figure 3-1. Map of the Estero Americano Watershed showing water quality sampling locations and aquatic habitat types. ……………32 Figure 3-2. Un-ionized ammonia levels at sampling stations in the watershed during the 1989/1990 winter. ……………33 Figure 3-3. Total phosphates levels in the watershed during the 1989/1990 winter. ……………34 Figure 3-4. Average minimum Dissolved Oxygen levels at sampling stations throughout the watershed during the 1989/1990 sampling season. ……………35 Figure 3-5. Maximum water temperatures throughout the watershed during the 1989/1990 sampling period. ……………36 Figure 3-6. Salinity (ppt) in the Estero April-September 1990. ……………37 Figure 3-7. Salinity (ppt) in the Estero during the winter of 1989/1990. ……………37 Figure 3-8. Average seasonal turbidity at sampling stations throughout the watershed. ……………38 Figure 3-9. Map of land use distribution in the watershed. ……………39 Figure 3-10. Annual Nitrogen loading in the three Subwatersheds. ……………41 Figure 3-11. Annual Phosphorus loading by subwatershed. ……………42 Figure 4-1. Erosion hazard and assessment map of the Estero Americano Watershed. ……………47 Figure 4-2. Abundance of riparian vegetation along major tributaries. ……………51 Figure 6-1. Map of parcels and stream reaches chosen for priority implementation of rangeland and riparian enhancement projects. ……………75 Chart 3-1. N Loading (lbs/yr) by Source ……………41 Chart 3-2. P Loading (lbs/yr) by Source ……………42 Chart 4-1. Estimated Sediment Loadings ……………49 Chart 4-2. Riparian Assessment by Sub-watershed ……………51 ESTERO AMERICANO WATERSHED MANAGEMENT PLAN – VERSION 1, FEBRUARY 2007 iv List of Abbreviations BMP Best Management Practice CAFO Confined Animal Feeding Operation CCRC Central Coast Rangeland Coalition CDQAP California Dairy Quality Assurance Program CDFG California Department of Fish & Game CNDDB California Natural Diversity Data Base CWA Federal Clean Water Act EPA United States Environmental Protection Agency EQIP Environmental Quality Incentives Program GIS Geographical Information System NCRWQCB North Coast Regional Water Quality Control Board NOAA National Oceanic and Atmospheric Administration NPDES National Pollution Discharge Elimination System NPS Nonpoint Source Pollution NRCS Natural Resources Conservation Service RCD Resource Conservation District RDM Residual Dry Matter SWRCB State Water Resources Control Board TAC Technical Advisory Committee TMDL Total Maximum Daily Load UCCE University of California Cooperative Extension USDA United States Department of Agriculture USGS U.S. Geological Survey WDR Waste Discharge Requirement WUD Western United Dairymen ESTERO AMERICANO WATERSHED MANAGEMENT PLAN – VERSION 1, FEBRUARY 2007 v Executive Summary The Estero Americano and its main tributary Americano Creek drain into Bodega Bay and the Gulf of the Farallones National Marine Sanctuary. The Estero Americano is a fjord-like estuary that extends from the Pacific Ocean, just south of Bodega Harbor, to the town of Valley Ford 4.0 miles inland. Americano Creek is roughly 7.6 miles in length and drains the upper third of the Estero Americano Watershed before flowing into the tidal estuary at Valley Ford. The 2002 California Water Quality Assessment Report published by the State Water Resources Control Board (SWRCB) listed 199 acres of the Estero Americano and the entire length of Americano Creek as impaired waterbodies due to nutrient pollution from agricultural sources. The Estero Americano is also listed as impaired due to sedimentation/siltation. The Estero Americano Watershed Management Plan was funded through the SWRCB as part of a Clean Water Act, Section 205(j) planning grant to focus efforts on identifying the potential sources of these water quality impairments and to identify land management solutions through a voluntary, cooperative planning process. The Gold Ridge Resource Conservation District (RCD) applied for and received funding to produce this document in the spring of 2004. The purpose of this watershed management plan is to characterize and assess the ecological processes and conditions of the Estero Americano Watershed, and to provide economically viable and agreed upon recommendations for improving water quality and the natural resource base through conservation-oriented land management practices. The Estero Americano Watershed Management Plan was developed over the course of two-and-a-half years of planning efforts involving numerous resource agency staff, watershed landowners, and other interested parties. A technical advisory committee (TAC) was organized early in the planning process and met two or three times a year to oversee technical planning elements and to provide guidance on the writing of the plan. Numerous interviews were conducted with watershed residents over the course of this planning study to gain valuable on-the-ground information about changes in the watershed, the value of its resources, along with any problems and issues encountered in the management of these resources. Two large public meetings were sponsored by the RCD to facilitate landowner participation in the planning process and to create a venue for public comment on the results of planning studies. The Agricultural Best Management Practices and Action Plan chapters