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Potentially Harmful Algal Bloom on Charles River 9/24 Update

September 24, 2015

The Cambridge Public Health Department modified the algal bloom advisory to include only the area of the Charles River from the Harvard Bridge (near Massachusetts Ave.) to the Museum of Science Dam.

This decision is based on recommendations from the state health department, which conducted a sixth round of water sample testing this week. Water sample test results were as follows:

  • BU Boathouse – Cyanobacteria levels tested below the state guideline for the second consecutive week.
  • Community Boating (Boston) – Cyanobacteria levels tested above the state guideline.
  • No microcystin toxin was detected in any sample.
On Aug. 13, state health officials notified the Cambridge Public Health Department that a water sample collected at Magazine Beach in Cambridge showed cyanobacteria concentrations roughly double the state’s guideline level.

The algal bloom was believed to extend from the Weld Boathouse near Harvard Square downstream to the Charles River Dam near the Museum of Science, according to the Charles River Watershed Association.

Microcystin toxins—commonly released by cyanobacteria—have not been detected in any Charles River water samples collected by state health officials.

The Massachusetts Department of Public Health will do another round of testing during the week of Sept. 28–Oct. 2.

Until the advisory is lifted, the Cambridge Public Health Department recommends that people and pets avoid contact with the algal bloom. For tips and resources, see the Aug. 14 advisory from the Cambridge Public Health Department.

For more information, contact the Massachusetts Department of Public Health at 617-624-5757 or visit www.mass.gov/dph/environmental_health. You can also contact the Cambridge Public Health Department at 617-665-3838.

Suzy Feinberg, MPH
Public Information Officer

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