Crystal Lake and Charles River Advisories

Crystal Lake is unsafe for swimming due to high levels of fecal coliform and e-coli bacteria. No people or pets should have contact with the water. Current bacteria levels can cause illness.

Water test results obtained today from a sample taken at Crystal Lake yesterday, Wednesday, August 5, 2020, indicate high levels of bacteria. For more specifics on the levels, click here.    
The high levels of bacteria may be the result of the recent heavy rain. Resampling has been conducted today and the results are expected on Saturday. They will be posted here as soon as possible.

In the meantime, we are posting signs at Crystal Lake indicating that the water is unhealthy.

Charles River

A cyanobacteria bloom (a.k.a., blue-green algae) was observed yesterday, on August 5, 2020, by the Charles River Watershed Association in sections of the Charles River in Newton, Weston and Waltham. Contact with the Charles River in this area is unsafe for people and pets. Cyanobacteria can cause illness.

The Massachusetts Department of Public Health will retest the river when the bloom is no longer visible.

For general questions about cyanobacteria, contact the Massachusetts Department of Public Health: 617-624-5757 or visit

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