McNears Beach
Tested by Marin County, usually every 7 days.
Taken 17 days ago. Results can take 1 to 3 weeks to be published, and many sites are tested less often in winter.
Every bacteria in this test: Total coliform 201 · E. coli 31 · Enterococcus 20. The grade follows the worst one against its own limit.
Grade A over 5 tests from Sep 29, 2026 to Oct 27, 2026. None were over the limit.
The latest test passed
Stay out for 72 hours after any rain of 0.2 in or more, when runoff raises bacteria everywhere along the coast.
Enterococcus over time
- Tuesday, Oct 27, 2026Total coliform 201 · E. coli 31 · Enterococcus 20
- Tuesday, Oct 20, 2026Total coliform 10 · E. coli 10 · Enterococcus 10
- Tuesday, Oct 13, 2026Total coliform 785 · E. coli 63 · Enterococcus 20
- Tuesday, Oct 6, 2026Total coliform 52 · E. coli 10 · Enterococcus 30
- Tuesday, Sep 29, 2026Total coliform 218 · E. coli 75 · Enterococcus 84
- Tuesday, Sep 22, 2026Total coliform 504 · E. coli 63 · Enterococcus 20
- Tuesday, Sep 15, 2026Total coliform 148 · E. coli 20 · Enterococcus 121
- Tuesday, Sep 8, 2026Total coliform 336 · E. coli 86 · Enterococcus 52
- Tuesday, Sep 1, 2026Total coliform 134 · E. coli under 10 · Enterococcus 10
- Tuesday, Aug 25, 2026Total coliform 134 · E. coli 52 · Enterococcus 10
Enterococcus and coliform bacteria live in the guts of people and animals. Health departments test for them because they travel with sewage, runoff and animal waste, so a high count is a warning that germs that do make people sick are likely in the water too. Clear water can still be contaminated: bacteria and viruses are too small to see.
San Diego County's DNA test (ddPCR) counts bacterial DNA instead of growing the bacteria in a lab, so it returns results the same day. Its numbers run higher than the older lab tests, which is why its safe limit is 1,413 rather than 104. The two are never compared on this page.
San Diego County's health department says swimming in water under an advisory can cause stomach illness, such as diarrhea and vomiting, and skin and ear infections. The EPA's national swimming guidelines are set at a level where about 32 to 36 of every 1,000 swimmers would get a stomach illness. A study of San Diego surfers found about 12 extra stomach-illness cases per 1,000 in wet weather, highest during rain and the day after, and back near normal 3 days later.
The grade is Nautical Nick's, built on the official limits: A is a quarter of the limit or less, B half or less, C under the limit, D over it, and F more than 10 times over. When a county posts an advisory or closes a beach, its sign is the final word.
Sources: California State Water Board beach test results; San Diego County Department of Environmental Health sample reports; Surfrider Foundation Blue Water Task Force; National Weather Service daily rain totals via the Iowa Environmental Mesonet (Napa Co. Airport). Limits: California Code of Regulations, Title 17, Section 7958.