Advisory

Advisory  DCR Recreation Advisory: Cyanobacteria Bloom in the Charles River 

Date: 08/21/2026

What: The Department of Conservation and Recreation (DCR) is warning the public of a cyanobacteria bloom present in the Charles River’s Lower Basin area in the cities of Boston and Cambridge, downstream from Harvard Bridge. During a bloom, it is strongly advised that the public should not have contact with the water. Additionally, pet owners should keep their animals away from the shoreline to prevent them from ingesting the water. This area will be retested once conditions visibly improve to determine whether cyanobacteria levels have fallen within acceptable limits per Department of Public Health (DPH) guidelines. For questions regarding cyanobacteria blooms, please contact DPH at (617) 624-5757 or visit the agency’s algae webpage.  

highlight of area

 Where: Charles River Lower Basin in the cities of Boston and Cambridge 

When: effective immediately – until further notice

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