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Beach water monitoring

Testing for water safety at 31 sites in Marin.
  • County of Marin, District 4, Stinson Beach ©Getty Image
    Stinson Beach water sampling location.
  • Chicken Ranch Beach Marin County
    Chicken Ranch beach water sampling location.
  • Whitehouse Pool water sampling location Marin County.
    Whitehouse pool water sampling location.
  • Shell Beach water sampling location Marin County.
    Shell Beach water sampling location.
  • Rodeo Beach water sampling location Marin County.
    Rodeo Beach water sampling location.
  • Muir Beach water sampling location Marin County.
    Muir Beach water sampling location.
  • Millerton beach water sampling location Marin County.
    Millerton Beach water sampling location.

What we do

Every week from April to the end of October each year, our team collects water samples from 31 locations across Marin. These locations include oceans, bays, and freshwater spots. We test these samples to make sure that they meet California's safety standards for:

  • swimming
  • wading
  • other recreational activities

The Napa-Solano-Yolo-Marin-Mendocino Public Health laboratory does our testing.

Please note: These water samples provide a water quality snapshot. Conditions may change from each day.

How will you know if the beach water is safe?

If the sampled water exceeds the State standards, we post a warning sign to alert the public. The California Department of Public Health advises the public to avoid contact with these waters.  

Where can you find the sampling results?

Current results are available online and are updated April thru October each year.

 

Related

Page last updated on July 24, 2025.