New York
Toxic algae in Oswego County lakes
11 lakes and waterways in Oswego County have harmful algal bloom reports in New York's official data. The most recent entry is for Lake Neatahwanta: Lake Neatahwanta was on New York's harmful algal bloom list on 13 September 2025, with confirmed bloom status (1 report). Lake Neatahwanta, South Sandy Pond and Oswego River and 4 more 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.
- Lake Temalo 2016
- Pennellville Pond 2016
- Vandercamp Lake 2018
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.