Mission Bay, Fiesta Island Bridge (south side)
Tested by San Diego County, usually daily.
Taken 330 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: Fecal coliform 48 · Total coliform 600. The grade follows the worst one against its own limit.
Grade D over 3 tests from Dec 16, 2025 to Dec 18, 2025. 2 were over the limit.
No recent test
The last test here was 330 days ago, too long ago to say anything about the water today. Some sites are tested only in summer. Stay out for 72 hours after any rain of 0.2 in or more, and check the county's status before going in.
County status: Advisory, checked Friday, Nov 13 (San Diego County Department of Environmental Health and Quality). The county’s posting is the final word.
Fecal coliform over time
- Thursday, Dec 18, 2025Fecal coliform 48 · Total coliform 600
- Wednesday, Dec 17, 2025Fecal coliform 920 · Total coliform over 10,000 · Enterococcus 50
- Tuesday, Dec 16, 2025Fecal coliform 1,800 · Total coliform 15,000 · Enterococcus 6
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 (San Diego/Montgomery Fld, San Diego/Lindberg). Limits: California Code of Regulations, Title 17, Section 7958.