RIDOH and DEM Lift Advisory at Flat River Reservoir (Johnson’s Pond)

RIDOH and DEM Lift Advisory at Flat River Reservoir (Johnson's Pond)

Published on Tuesday, November 04, 2025

The Rhode Island Department of Health (RIDOH) and Rhode Island Department of Environmental Management (DEM) have lifted the advisory recommendation to avoid recreational activities at Flat River Reservoir (Johnson's Pond) in Coventry. The harmful algae bloom (HAB) caused by blue-green algae (cyanobacteria) has cleared. Recent testing shows algae levels are low and no toxins were detected, meeting safety guidelines.

HAB conditions can change quickly, and blooms may affect Flat River Reservoir again, or other areas in Rhode Island. Water with HABs may be bright to dark green with thick, floating algal mats. The water may look like green paint, thick pea soup, or green cottage cheese. If you see water like this, keep people and pets away from it. Toxins may persist in the water after a blue-green algae bloom is no longer visible.

To report suspected blue-green algae blooms, contact DEM's Office of Water Resources at 401-222-4700 Press 6 or [email protected] and if possible, send a photograph of the reported algae bloom. For more information and the Cyanobacteria Tracker Dashboard that lists current advisories and data, visit: https://www.dem.ri.gov/bluegreen