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Watershed Maps
What’s a Watershed? Which One Are You Located In?
A watershed is a land area that drains water into a stream, lake, wetland, bay or estuary, or percolates into groundwater. Watersheds come in different shapes and sizes. Local watersheds are parts of larger, regional basins. Our Santa Clara basin, for example, is a sub-basin of the larger San Francisco Bay Basin.

A watershed begins at the top of a hill or mountain ridge and is ultimately defined by gravity. The Santa Clara Basin is bounded by the Diablo Mountains to the east and the Santa Cruz Mountains to the south and west. South San Francisco Bay receives the runoff water of our watersheds.

San José has six major watersheds:
  • Coyote
  • Guadalupe
  • Lower Penintenica
  • San Tomas
  • Calabazas
  • Baylands

Storm Drain Inlets
There are approximately 30,000 storm drain inlets within the City of San José, and each flows to a creek, river, or the Bay.

Find out which watershed you live in and where your storm drains flow by viewing the maps below. You can also read the stencil on the storm drain near your house or business. The City marks storm drain inlets with a “NO DUMPING” message that includes the name of the waterbody that the inlet drains to and stormwater hotline phone number, (408) 945-3000.

Storm Drains on Private Property
If the storm drain inlets on your private property (not in the right-of-way) are in need of stenciling with “NO DUMPING” messages, the Watershed Protection Division of the Environmental Services Department will provide you with stencils and instructions at no charge. To obtain the stencils, please contact the Watershed Protection Division at (408) 945-3000 and be prepared to provide the following information:
  • Contact Information
    • Name
    • Phone number
    • Either the company name for commercial or industrial property or the complex name (multi-family housing)
  • Site information
    • Name of site (e.g., name of shopping center or store, condo complex, industrial company)
    • Address
    • Nearest cross street
    • Number of inlets to be stenciled

Daily Activities Can Impact Our Watershed
  • Common pollutants such as litter, oil, soap, paint, copper, nickel, mercury, and pesticides can degrade, or impair, water quality in our local creeks and rivers.
  • Less commonly recognized pollutants, such as leaves or landscape clippings can reduce the amount of oxygen available in the creeks for fish which makes it difficult for fish to live. Even soil and sediment can impair water quality, both by degrading spawning habitat in the creeks and by carrying pollutants such as copper, nickel and other heavy metals that readily bind to sediment.
  • Rivers carrying excessive sediment and other pollutants can significantly reduce spawning habitat for fish, which in turn impacts other wildlife. These pollutants, individually and cumulatively, adversely affect fish, plants and wildlife that live in and depend on the City’s rivers and creeks.
  • Learn more at For free landscaping workshops, visit South Bay Green Gardens.