New York

Toxic algae in New York County lakes

4 lakes and waterways in New York County have harmful algal bloom reports in New York's official data. The most recent entry is for Harlem Meer: Harlem Meer was on New York's harmful algal bloom list from 15 July 2025 to 23 September 2025, with confirmed bloom status (8 reports). Harlem Meer, Turtle Pond and Morningside Pond 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.

Harlem Meer Latest 15 July 2025, blooms in 12 years Confirmed bloom
Turtle Pond Latest 12 June 2025, blooms in 11 years Confirmed bloom
Morningside Pond Latest 9 June 2025, blooms in 10 years Confirmed bloom

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.

Croton Reservoir 2022

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.