Stormwater Management & Pollution Prevention

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Stormwater runoff from urbanized areas is the largest source of pollution to the nation's waters. Municipalities in urbanized portion of the San Francisco Bay Area are responsible for controlling stormwater pollution by complying with municipal stormwater National Pollutant Discharge Elimination System (NPDES) permits. The development or redevelopment of property represents an opportunity to incorporate treatment measures that can reduce water quality impacts, not only during construction, but also over the life of the project.

The following provides a link to the San Mateo Countywide Water Pollution Prevention Program website, which contains pertinent information and forms regarding on-site stormwater treatment: San Mateo Countywide Water Pollution Prevention Program

If you need additional assistance, please contact Howard Young, Public Works Director at 650-851-1700 ext. 215 or


Stormwater Pollution Prevention at Home

Visit San Mateo County's Stormwater 101 page to learn more about water pollution prevention.

Local Watershed

A watershed is the land that water flows over or through on its way to a creek, delta, bay, or ocean. Everyone lives in a watershed, and everything that happens in the watershed affects water quality and habitat quality for fish, birds and other living things. Pollution in distant parts of a watershed can be washed into storm drains, and cause problems downstream. Human activities can harm or improve the condition of a watershed, including its water quality, its fish and wildlife, its forests and other vegetation, and the quality of life for people who live there. Most of the stormwater runoff in San Mateo County eventually drains into the San Francisco Bay or the Pacific Ocean. There are 34 watersheds in San Mateo County. Portola Valley is in the San Francisquito Watershed. Click here to view the watershed map.