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COVID-19 Updates: Get the latest public information related to coronavirus disease 2019 (COVID-19) at

Public Works office buildings are closed to the public in an effort to keep the community and staff safe.  However, we are still conducting business via email, [email protected] or phone calls, 805-781-5252.  Follow us on Twitter @SLOCountyPWD for the latest updates.

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Public Works

County of San Luis Obispo

Watershed Sanitary Surveys

Watershed Sanitary Surveys are required byt the State Water Resources Control Board Division of Drinking Water for all surface water influenced water supplies. The surveys must be updated every 5 years, with 4 main goals:

  1. Identify existing sources of water contamination.
  2. Identify potential future sources of water contamination.
  3. Provide a baseline of water quality and watershed condition for identification of trends in future survey updates.
  4. Recommend watershed management practices that will protect raw water quality of this valuable local water source and minimize the need to import water.

Click on each location below to view their Watershed Sanitary Survey:

Lopez Lake and Terminal


Santa Margarita Area


Salinas Reservoir


Nacimiento Lake


Nacimiento Water Project


Whale Rock Reservoir