About
Why this exists
Bay Area Swim is a solo side project. It started because there is no single place to check water-quality status across all Bay Area swim spots at once — bacteria results live in one state dataset, rain forecasts live in another API, and park-district postings live on half a dozen separate pages. This site stitches that data together so a trip to the beach starts with one glance rather than half an hour of tab-hopping.
How it works
Bay Area Swim pulls bacteria sampling data from the California Safe-to-Swim dataset (data.ca.gov) and precipitation data from Open-Meteo. Every morning the pipeline scores each swim spot as safe, caution, unsafe, or unknown using EPA thresholds.
Risk scoring
- Unsafe: Enterococcus single sample >104 or geomean >35 MPN/100mL; E. coli >235; 48h rain >25.4mm at enclosed beaches.
- Caution: 72h rain >12.7mm.
- Safe: All signals within limits.
- Unknown: No data in 14+ days, or off season.
Methodology
Every data point has a source, a license, and a fetch timestamp. Full attribution and lineage — including which agency sampled which beach — is on the Data Sources page.
Refresh cadence
Data updates daily by 7am PT. Bacteria sample cadence varies by agency (weekly to daily). Some agencies (SFDPH, CMaEHS) pause sampling November through March under California's AB411 mandate; those spots will show "unknown" in winter until sampling resumes.
Contact
Questions, corrections, or a missing swim spot? Email patrickbeekman1095@gmail.com.
Not medical advice.
Water conditions change rapidly. Always check official agency postings at the swim spot before entering the water.