New York
Toxic algae in Westchester County lakes
31 lakes and waterways in Westchester County have harmful algal bloom reports in New York's official data. The most recent entry is for Truesdale Lake: Truesdale Lake was on New York's harmful algal bloom list on 6 October 2025, with confirmed bloom status (1 report). Truesdale Lake, Muscoot Reservoir and New Croton Reservoir and 7 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.
- Truesdale Lake Confirmed bloom
- Muscoot Reservoir Confirmed bloom
- New Croton Reservoir Confirmed bloom
- New Rochelle Reservoir No.1 Confirmed bloom
- Lake Lincolndale Confirmed bloom
- Lake Purdys Confirmed bloom
- Lake Mohegan Confirmed bloom
- Halsey Pond Confirmed bloom
- Kensico Reservoir Not listed in 2025
- Bedford Lake Not listed in 2025
- Lake Waccabuc Not listed in 2025
- Sheldrake Lake Not listed in 2025
- Glenwood Lake Not listed in 2025
- Lake Oscaleta Not listed in 2025
- Lake Rippowam Not listed in 2025
- New Rochelle Reservoir No.3 Not listed in 2025
- Lake Katonah Not listed in 2025
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.
- Amawalk Reservoir 2023
- Blue Heron Lake 2014
- Cortlandt Lake 2018
- Cross River Reservoir 2023
- Goodliffe Pond 2016
- Grassy Sprain Reservoir 2014
- Huguenot Lake 2021
- Lake Mitchell 2025
- Lounsbury Pond 2016
- Mohansic Lake 2024
- Paine Lake 2018
- Silver Lake 2017
- Swan Lake 2024
- Tarrytown Reservoir 2013
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.