New York
Toxic algae in St. Lawrence County lakes
8 lakes and waterways in St. Lawrence County have harmful algal bloom reports in New York's official data. The most recent entry is for Black Lake: Black Lake was on New York's harmful algal bloom list from 10 July 2025 to 23 September 2025, with confirmed bloom status (16 reports). Black Lake and Silver Lake have had blooms in three or more years.
Lakes with bloom history
Newest report first. Each lake has its own page with the full history and what the results mean.
Other waterbodies with a report
These have one or two reports in a single year, which isn't enough history for a page of their own yet.
- Cranberry Lake 2024
- Lake Ozonia 2024
- Lake St Lawrence 2022
- St Lawrence River 2017
- Star Lake 2024
Source: New York State Department of Environmental Conservation (DEC), official data, checked 24 October 2026. For today's conditions see the NYHABS map. No report doesn't mean a lake is safe: most water is only tested occasionally.