Data sources
Every figure on this site comes from a public source. Attribution is required by the open-data licenses that make these datasets free to use.
California Safe-to-Swim
ODbL 1.0Statewide aggregator for ocean and bay beach bacteria sampling — Enterococcus, E. coli, fecal coliform, and total coliform results submitted by county health departments and the State Water Board. Drives the bacteria-based risk signal on most coastal beach pages.
SF DataSF — Beach Water Quality
Public DomainSan Francisco DPH's beach water-quality results, refreshed weekly during the bathing season. Covers Aquatic Park, Crissy Field, Baker Beach, China Beach, and Ocean Beach sampling stations within the city — the only feed that publishes SF beach data on a same-week cadence.
East Bay Regional Park District Lakes
Public DomainLive scrape of EBRPD's water-quality page plus per-lake PDFs and stoplight monitoring pages. Drives the bacteria + HAB advisory signal for Lake Temescal, Lake Anza, Del Valle, Shadow Cliffs, Crown Beach, Keller Beach, and Niles Beach.
City of Berkeley — Aquatic Park Water Quality
Public DomainBerkeley's PDF report covering Aquatic Park's three lagoons (North, Middle, South). Parsed weekly with pdfplumber; provides the only structured Enterococcus history for the East Bay's main enclosed-water swim spot.
NOAA CO-OPS — Water Temperature
Public DomainHourly water-temperature observations from NOAA's Center for Operational Oceanographic Products and Services tide stations around the bay (Alameda, Richmond, Point Reyes, etc.). Currently shown only in the dashboard view; not part of the safe/caution/unsafe risk score.
NOAA NDBC — Buoy Observations
Public DomainNational Data Buoy Center moored buoys outside the Golden Gate and along the coast. Provides wave height, period, and offshore sea-surface temperature. Used as a contextual / surf-condition signal in the dashboard; not part of the bacteria risk score.
Open-Meteo — Precipitation
CC-BY 4.0Free weather API providing hourly precipitation (past 7 days plus 7-day forecast) batched per-location. Powers the rainfall advisory: 48h totals above 1.0 in or 72h totals above 0.5 in trigger caution/unsafe flags on every beach page.
Marin County — Beach Water Quality
Esri Standard (as-is)Official Marin County beach status postings published weekly via ArcGIS Online. Covers 31 stations along the Marin Pacific coast (Stinson, Muir, Bolinas, Drakes, Rodeo, and others) with OK/AVOID/N/A status. Provides authoritative county postings and sub-station granularity not available in the state feed.
U.S. EPA Recreational Water Quality Criteria
Public domainSource for the bacteria thresholds used in the risk-scoring model: Enterococcus single sample 104 MPN/100mL and 30-day geomean 35; E. coli single sample 235 and geomean 100; fecal coliform single sample 400.
What's not in the risk score
- EBRPD freshwater lakes are seeded manually from the park district's advisory pages. An automated scraper is planned for a future phase.
- NOAA / NDBC water temperature and waves are shown on the map dashboard for convenience, but are not currently inputs to the safe / caution / unsafe score.
- Blue-green algae advisories are not yet integrated. When an agency posts an HAB advisory, check its official page directly before swimming.