New York
Toxic algae in Chenango County lakes
13 lakes and waterways in Chenango County have harmful algal bloom reports in New York's official data. The most recent entry is for Thunder Lake: Thunder Lake was on New York's harmful algal bloom list from 28 July 2025 to 13 September 2025, with confirmed bloom status (2 reports). Thunder Lake, Plymouth Reservoir and Chenango 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.
- Balsam Pond 2021
- Bowman Lake 2016
- Glenn Lake 2016
- Lake Petonia 2025
- Norwich Reservoir East 2016
- Warn Lake 2016
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.