Hydrology and Water Quality Existing Conditions for San José California Envision San José 2040 May 18, 2009 Schaaf & Wheeler CONSULTING CIVIL ENGINEERS 870 Market Street, Suite 1278 San Francisco, CA 94102 Tel: (415) 433-4848 Fax (415) 433-102 Hydrology & Water Quality Existing Conditions Introduction .................................................................................................................................................................1 Environmental Setting ................................................................................................................................................1 Regional Setting.......................................................................................................................................................1 Topography ..............................................................................................................................................................4 Climate .....................................................................................................................................................................4 Land Use ..................................................................................................................................................................5 Geology and Soils...................................................................................................................................................10 Surface Water ........................................................................................................................................................13 Surface Water Reservoirs................................................................................................................................13 Flood Management ..........................................................................................................................................20 Surface Water Quality.....................................................................................................................................28 Tidally Influenced Areas .................................................................................................................................31 Other Surface Water Hazards ........................................................................................................................33 Watersheds within the City of San Jose ................................................................................................................35 San Tomas Watershed .....................................................................................................................................36 Guadalupe River Watershed...........................................................................................................................41 Coyote Creek ....................................................................................................................................................55 Water Supply .............................................................................................................................................................64 San Francisco Public Utilities Commission..........................................................................................................66 Santa Clara Valley Water District .........................................................................................................................66 Groundwater ..........................................................................................................................................................70 Santa Clara Valley Sub-Basin.........................................................................................................................72 Coyote Valley Sub-Basin .................................................................................................................................73 Groundwater Discharge Components............................................................................................................73 Groundwater Recharge Components.............................................................................................................74 Groundwater Levels ........................................................................................................................................76 Groundwater Quality ......................................................................................................................................79 Recycled Water.......................................................................................................................................................81 Regulatory Framework.............................................................................................................................................83 Federal Regulations...............................................................................................................................................83 National Flood Insurance Program................................................................................................................83 Clean Water Act...............................................................................................................................................84 National Pollutant Discharge Elimination System Permit ...........................................................................85 U.S. Army Corps of Engineers........................................................................................................................85 State Regulations ...................................................................................................................................................86 California Water Resources Control Board ..................................................................................................86 NPDES Municipal Stormwater Permit ..........................................................................................................86 NPDES General Permit for Discharges of Stormwater Associated with Construction Activity...............86 NPDES Industrial Discharge Permit(s)..........................................................................................................87 California Fish and Game Code - Lake and Streambed Alteration ............................................................87 California Department of Public Health, Drinking Water Program...........................................................88 Senate Bills 221 and 610 ..................................................................................................................................88 Urban Water Management Plans ...................................................................................................................90 Dam Safety........................................................................................................................................................90 Local Regulations ..................................................................................................................................................91 City of San Jose ................................................................................................................................................91 Santa Clara Valley Water District..................................................................................................................99 San Francisco Bay Conservation and Development Commission Permit Program...................................99 Current Status of Regulations Pertaining to Climate Change.............................................................................99 Federal ..............................................................................................................................................................99 State.................................................................................................................................................................101 Local................................................................................................................................................................105 Hydrology & Water Quality Existing Conditions 1.0 Introduction The City of San José’s General Plan was adopted in 1994, and is used by the City in making day to day decision regarding land use, development, and City Services. In June, 2007, the City Council of San José initiated a comprehensive update of the City’s General Plan, titled Envision San José 2040. The first step of any general plan is to create a comprehensive understanding of existing conditions. To that end, this report was prepared by Schaaf & Wheeler to detail the existing conditions within the City of San José Urban Growth Boundary as related to hydrology, water quality, and water supply, including regional surface water and groundwater issues. This report first examines the environmental setting of the City Urban Growth Boundary including a discussion of land use as it relates to water resources, surface water features, water quality, and flood risks. A brief discussion of possible climate change impacts relevant to City planning is included in this section. Water supply to the City is discussed, including groundwater resources and groundwater quality. Finally, the regulatory framework that impacts water resources in the City is discussed. 2.0 Environmental