Health Advisory Cyanobacteria in the Charles River

The Boston Public Health Commission warned residents to avoid contact with the Charles River downstream of the Harvard Bridge due to a harmful cyanobacteria algae bloom. Assessments conducted by DPH staff found cyanobacteria levels surpassing recreational water safety guidelines, which pose significant health risks. The advisory advises against swimming, fishing, and other water activities, and instructs pet owners to prevent their dogs from swimming or drinking the contaminated water. Toxins from the bloom can lead to acute gastrointestinal symptoms in humans and serious health issues in animals, including possible fatalities. The Massachusetts Department of Public Health will continue to monitor the algae levels and will conduct laboratory tests to assess when the advisory can be lifted.

Residents should rinse off immediately if they come into contact with the water. The bloom may persist for weeks, and the DPH requires two consecutive rounds of testing below a specified threshold to lift the advisory. For more information, residents can reach out to the Boston Public Health Commission.