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What Is a Watershed?

A watershed is a land area where water collects and flows into a larger body of water like a river or ocean. It can be small or large and can span across different areas, including counties, states, and even countries. Every location, including your home, is part of a watershed.


Map of watersheds in Contra Costa County.

There are 31 major watersheds in Contra Costa County that drain to the Bay or Delta. Additionally, Contra Costa County includes the headwaters of creeks that drain through other counties before reaching the Bay. Below are watersheds in the County and San Ramon.

 For more information, visit the  Contra Costa Resource Conservation District website for a copy of the Contra Costa Watershed Atlas.


How to Prevent Pollution?

  • Reuse and recycle items and keep trash and litter out of gutters and storm drains. Go to our  Garbage and Recycling webpage for information on how to start garbage, recycling, and organics service. For information on what is accepted in each container, visit ACI of San Ramon.
  • Dispose of your Household Hazardous Waste (HHW) properly! Visit our Hazardous/Electronic Waste webpage for more information.
  • Use less-toxic products to manage pests in your yard and garden and to protect your pets. Visit the Contra Costa Clean Water Program's  Yards, Gardens, and Pets webpage has information on how to control common pests and how to maintain a healthy garden and lawn.
  • Recycle used motor oil and filters, and other automotive fluids, by taking them to certified used oil collection site.  Information and locations can be found on the  Contra Costa Clean Water Program website. And take your car to a commercial car wash instead of washing it at home. You can also look at services offered by ACI of San Ramon.
  • Report illegal dumping and spills to gutters and storm drains by reporting Illegal dumping using the Citizen Request Management (CRM) Tool or call 925-973-2670.