Swimmers and their pets are being told to avoid swimming in the Charles River in Boston after a high levels of bacteria was found in the water.
The Massachusetts Department of Conservation and Recreation says a cyanobacteria bloom is present within the Charles River Lower Basin in Boston and Cambridge.
No timeline on how long this warning will last.
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The water will be retested until cyanobacteria levels are within acceptable limits per Department of Public Health regulations.
Less than a month ago, intrepid swimmers dove into the Charles for the annual "City Splash." It is one of the few days the state permits public swimming on the city's stretch of the 80-mile river.
The event, spotlights the nonprofit Charles River Conservancy's efforts to make the river "swimmer-friendly", despite its notorious dirty past.