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Despite a cyanobacteria bloom outbreak, the world-renowned regatta is still on track to kick off on Oct. 17, drawing about 12,000 rowers to the water.
Jessica Rinaldi/Globe Staff
An outbreak of toxic cyanobacteria is plaguing the Charles River just a week before the waterway hosts the world’s largest three-day rowing competition.
The 2025 Head of the Charles Regatta takes place in Boston and Cambridge from Oct. 17 to 19. The iconic event will feature roughly 12,000 rowers and draw thousands of spectators along the Charles River.
According to a Mass.gov emergency alert, the water downstream of the Cambridge Street/River Street bridge and Back Bay Fens has been reported harmful as of Oct. 6.
“With climate change bringing increased precipitation and extreme heat, cyanobacteria blooms are becoming more frequent and long-lasting,” Stefan Geller, of the Charles River Watershed Association, told the Boston Globe. “The Charles River has had cyanobacteria blooms almost every summer for the last decade.”
Due to high temperatures and heavy rainfall, several Massachusetts waterbodies have developed cyanobacteria blooms, according to the Department of Public Health.
“If you think an algal bloom may be present, you are encouraged to avoid contact with the water — WHEN IN DOUBT, STAY OUT!” state officials wrote on the emergency alert.
The blue-green algae can cause skin rashes and eye irritation in people who come in contact with it, according to the Centers for Disease Control. For that reason, rowers at the Head of the Charles could be at risk of experiencing a reaction to the cyanobacteria.
Organizers say the event will go on as planned, as they anticipate the cooler temperatures will help clear the blooms. However, a regatta spokeswoman told the Globe that organizers are working closely with state officials to monitor the situation.
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