BIG SUR RIVER WATERSHED MANAGEMENT PLAN A Guidance Document For Voluntary Stewardship Efforts To Maintain And Enhance The Quality of Big Sur River Watershed Steelhead Habitat This page intentionally left blank BIG SUR RIVER WATERSHED MANAGEMENT PLAN December 2014 Prepared by: Paul Robins [email protected] Stephnie Wald [email protected] Ethan Bell and Zooey Diggory [email protected] [email protected] Doug Smith and Sam Phillips [email protected] Jennifer Nelson and Margaret Paul [email protected] [email protected] In fulfillment of a grant P1140400 from the California Department of Fish and Wildlife Fisheries Restoration Grant Program Cover photographs: Stillwater Sciences Resource Conservation District of Monterey County, Central Coast Salmon Enhancement, Stillwater Sciences and California State University of Monterey Bay. 2014. Big Sur River Watershed Management Plan. Prepared for the California Department of Fish and Wildlife, under a grant for the Fisheries Restoration Grant Program (P1140400). Table of Contents EXECUTIVE SUMMARY .......................................................................................................................................5 1 INTRODUCTION .......................................................................................................................................7 1.1 Purpose, Need and Intended Use of the Watershed Plan .........................................................7 1.2 Goals and Objectives ......................................................................................................................7 1.3 Overview of the Watershed ...........................................................................................................8 1.4 Watershed History ........................................................................................................................11 1.5 Stakeholder Involvement in the Watershed Plan ......................................................................16 1.5.1 Stakeholder Issues and Concerns ...................................................................................17 1.6 Related Studies and Plans ............................................................................................................17 2 SYNTHESIS OF WATERSHED CONDITIONS .................................................................................21 Physical Features 2.1 Hillslope and Channel Geomorphology ....................................................................................21 2.1.1 Sediment production, transfer, and storage ..................................................................22 2.1.2 Channel morphology .......................................................................................................26 2.2 Geology, Tectonics, and Soils ......................................................................................................32 2.2.1 Roads and Trails ..............................................................................................................36 2.3 Climate ...........................................................................................................................................37 2.3.1 Precipitation .....................................................................................................................39 2.3.2 Climate Change ................................................................................................................41 2.4 Wildfire ..........................................................................................................................................44 Existing Conditions 2.5 Land Use ........................................................................................................................................47 2.5.1 Current land uses and economic activity ......................................................................47 2.5.2 Land use planning ............................................................................................................47 2.5.3 Growth trends in Monterey County ..............................................................................49 2.5.4 Land use controls..............................................................................................................49 2.5.5 Applicable Permit Streamlining Programs ...................................................................49 2.6 Surface and Groundwater Hydrology ........................................................................................50 2.6.1 Surface Hydrology ............................................................................................................50 2.6.2 Flood Mapping (25, 50, 100, 500 year) ..........................................................................54 2.6.3 Lagoon Hydrology and Morphology .............................................................................55 2.6.4 Groundwater .....................................................................................................................57 2.7 Water Quality ................................................................................................................................58 2.7.1 River water qaulity ...........................................................................................................59 2.7.2 Lagoon water qaulity ........................................................................................................65 BIG SUR RIVER WATERSHED MANAGEMENT PLAN 1 BIG SUR RIVER WATERSHED PLAN Contents, continued 2.7.3 Bioassessment ................................................................................................................. 66 2.7.3.1 Methods ..........................................................................................................67 2.7.3.2 Benthic macroinvertebrate data ...................................................................69 2.7.3.3 Supporting data ..............................................................................................70 2.8 Instream Infrastructure and Channel Modifications ...............................................................73 2.8.1 Bank revetment and floodplain development ..............................................................73 2.9 Vegetation ......................................................................................................................................74 2.9.1 Vegetation types and distribution ..................................................................................74 2.9.2 Rare plant species and vegetation types ........................................................................77 2.9.3 Non-native invasive plant species ..................................................................................77 2.9.4 Riparian vegetation conditions .......................................................................................83 2.10 Wildlife ...........................................................................................................................................84 2.10.1 California Red-legged Frog .............................................................................................84 2.10.2 Pacific lamprey ..................................................................................................................85 2.10.3 Smith’s blue butterfly .........................................................................................................85 2.10.4 Pacific pond turtle ............................................................................................................85 2.10.5 Tidewater goby .................................................................................................................85 2.10.6 Non-native, invasive wildlife species .............................................................................85 3 STEELHEAD ............................................................................................................................................88 3.1 Population ......................................................................................................................................88 3.1.1 Status and Population Structure .....................................................................................88 3.1.2 Population Estimates........................................................................................................89 3.1.3 Distribution .......................................................................................................................89 3.2 Life history and Habitat Requirements ......................................................................................89 3.3 Limiting Factors ............................................................................................................................91 3.3.1 Fish passage .....................................................................................................................92 3.3.2 Fine Sediment .................................................................................................................96 3.3.3 Spawning Habitat ..........................................................................................................98 3.3.4 Rearing Habitat ..............................................................................................................99 3.3.5 Food Availability and Size at Smolting ........................................................................99