MWRA’s Chestnut Hill Reservoir is located in Boston and bordered by Newton and Brookline. It is an emergency backup water supply reservoir, that would only be used under emergency circumstances (last used in 2010). Through routine water quality testing, MWRA recently discovered that a cyanobacteria bloom (commonly referred to as blue green algae) and an associated algal toxin, have been detected in this backup reservoir. Similar blooms have been reported in other locations throughout the state. Signs notifying the public will be posted around the reservoir due to the levels detected. The posting will advise no swimming, no fishing, no contact with water and to keep animals away. These activities are already prohibited at this emergency back up reservoir. MassDEP and DPH have been notified.
MWRA is continuing to test the water and will provide updates.