HARWICH — A blue-green algae bloom turned the waters of the West Reservoir in the Bell’s Neck Conservation Area bright green Monday. Town officials warned people not to swim or allow dogs to swim or drink water from the reservoir.
“The whole West Reservoir is a murky blue-green,” Conservation Administrator Amy Usowski said after posting three warning notices along the shoreline where people might come in contact with the pond.
The notice states: “Potentially toxic Blue-Green Algae Bloom. Please do not swim in, or let your dogs swim in or drink out of this water. The bloom should only last a couple of days.”
Health Department Director Meggan Eldredge was out sick on Monday but Usowski said the Health Department is aware of the situation. She said the waters have not been tested for the presence of cyanobacteria, which is often a product of the algae bloom. Cyanobacteria can cause gastroenteritis, liver, kidney and neurological impacts, especially in animals. Because there are no public bathing beaches in the reservoir, the waters are not tested regularly. While people don't swim in the waters often, it is an area where a lot of people walk their dogs, Usowski said.
The reservoir is a shallow freshwater body that is connected to the Herring River just above the Johnson’s Flue fish ladder. The river flows down from Hinckley’s Pond, which had a similar algae bloom several weeks ago. Hinckley’s Pond, a much deeper water body, has had a history of blue-green algae blooms with the presence of cyanobacteria.
Such algae blooms are often caused by an overload of phosphorus and sometimes also lead to fish kills. The town is planning an alum treatment application in Hinckley's Pond in September designed to bind phosphorus in the sediment to prevent future blooms.