About the data
Is The Lake Safe? brings official harmful algal bloom records from state agencies into one place, with a page for every lake that has enough history to be useful.
Sources
| State | Agency | Updates | Latest entry |
|---|---|---|---|
| New York | New York State Department of Environmental Conservation (DEC) | published as a yearly summary; the current season is shown on the NYHABS map | 19 November 2025 |
| Florida | Florida Department of Environmental Protection (DEP) | published as a yearly file; current sampling is shown on the DEP dashboard | 30 December 2025 |
| California | California State Water Resources Control Board | updated daily | 19 October 2026 |
Site rebuilt 24 October 2026.
How we build the pages
We group each state's reports by waterbody. Large lakes that cross county lines are combined into one page. A lake gets its own page when it has at least three reports or reports in two different years. Waterbodies with fewer reports are listed on their county page. Sampling locations that aren't a waterbody, such as bridges or station codes, are left out.
What this site can't tell you
States test only some lakes, and only some of the time. A lake without a recent report hasn't necessarily been checked, and blooms can appear or move within hours. This site is for information only and isn't health or medical advice. Always follow posted signs and local health officials, and keep people and pets away from green, scummy or discoloured water.
Independence
Is The Lake Safe? is an independent website. It isn't affiliated with or endorsed by any government agency. Official data is republished with credit to each agency.