To report elevated bacteria levels in local recreational waters, please email Marin County Environmental Health Services or call at 415-473-7146.
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Stinson Beach water sampling location. -
Chicken Ranch beach water sampling location. -
Whitehouse pool water sampling location. -
Shell Beach water sampling location. -
Rodeo Beach water sampling location. -
Muir Beach water sampling location. -
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.
Beach Water Quality Monitoring Update
Seasonal water quality monitoring has concluded for 2025. Routine sampling will resume in April 2026.
Thank you for your interest in our water quality program. Please check back in the spring for updated results.
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.
- Beach water quality information shows 4 weeks of results by location.
- Current beach water samples map provides results on a map for just 1 week.
- For a recorded list of waters safety issues, call 415-473-2335.