Harmful Cyanobacterial Bloom Advisories in Massachusetts current as of October 16, 2025

This list includes waterbodies that have been reported to DPH by local, state and federal partners that manage or regulate the respective waterbody.

  • Lake Holland, Belchertown
  • Back Bay Fens, Boston
  • Charles River-- (Downstream of the MIT Boathouse), Boston/Cambridge
  • Sprague Pond, Boston
  • Walkers Pond, Brewster
  • Brookline Reservoir, Brookline
  • Chebacco Lake, Essex/Hamilton
  • West Reservoir, Harwich
  • Redd’s Pond, Marblehead
  • Santuit Pond, Mashpee
  • Carbuncle Pond, Oxford
  • Pontoosuc Lake, Pittsfield
  • Billington Sea, Plymouth
  • Boot Pond, Plymouth
  • Clear Pond, Plymouth
  • Ezekiel Pond, Plymouth
  • Great South Pond, Plymouth
  • Little West Pond, Plymouth
  • Round Hole Pond (Esta Drive), Plymouth
  • Scokes Pond, Plymouth
  • Beaman Pond, Templeton
  • Lake Quannapowitt, Wakefield
  • Willett Pond, Walpole/Norwood
  • Hardy Pond, Waltham

Please note: This should not be considered a complete list of all advisories in Massachusetts. This list includes waterbodies that have been reported to DPH by local, state and federal partners that manage or regulate the respective waterbody. If you think an algal bloom may be present you are encouraged to avoid contact with the water — WHEN IN DOUBT, STAY OUT! To see examples of what algae blooms look like, please visit the Identifying cyanobacterial blooms and scums page.

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