Cyanobacteria Bloom at Pawtuckaway Lake 5/27/2026

Please visit the Healthy Swimming Mapper for the most current information about bloom location, status, and severity.

Cyanobacteria reports depict only what an observer sees in the water. The report may reflect a waterbody wide perspective if they boated around the waterbody and made observations, or it could be a single sighting from the shoreline. One sighting does not indicate that a warning is necessary, but it does indicate that those on or around the waterbody should be aware that cyanobacteria have been observed beyond what is natural, and that they should be on the lookout for shifting bloom conditions and report them via the Bloom Report Form. Reports will be removed from the Healthy Swimming Mapper after one week if no further reports are received.

Warnings are issued when samples are evaluated microscopically, and cell counts exceed 70,000 cells/mL and the bloom is widespread or extends to multiple locations on the waterbody. A warning does not close the waterbody to recreational use. The warning is intended as a precautionary measure to inform the public of the potential health risks associated with cyanobacteria blooms. Please see our FAQs for more information.

NHDES advises lake users to not swim in or near the vicinity of where bloom material is visible. Please also keep pets and livestock out of areas where bloom material is observed. It is suggested that local authorities post an informational cyanobacteria sign at public access points.

The CyanoHAB Team
Cyanobacteria Harmful Algal Bloom Program
Watershed Management Bureau, Water Division
New Hampshire Department of Environmental Services
29 Hazen Drive, P.O. Box 95, Concord, NH 03302-0095
603-848-8094   [email protected]