New York
Toxic algae in Onondaga County lakes
10 lakes and waterways in Onondaga County have harmful algal bloom reports in New York's official data. The most recent entry is for Hiawatha Lake: Hiawatha Lake was on New York's harmful algal bloom list from 2 September 2025 to 4 October 2025, with confirmed bloom status (4 reports). Hiawatha Lake, Skaneateles Lake and Oneida River and 3 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.
- Gillie Lake 2024
- Marcy Street Pond 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.