Halifax– From June 6 to June 14, the contractor SOLitude Lake Management applied a phosphorus-limiting agent to West Monponsett Pond. Cyanobacteria, also known as blue-green algae, feed on phosphorus. According to Dominic Meringolo, a senior environmental engineer with SOLitude, aluminium sulfate and sodium aluminate have been applied in low doses as far back as 2012 to reduce cyanobacteria with only limited success.
This time is different, he says, because through a matching grant with the town of Halifax and the federal government’s Clean Water Act– administered by MassDEP– more money is available and the doses will be much higher, aiming to immediately block the bloom.
“No bloom is expected this summer,” said Meringolo.
To obtain the grant, the town and the contractor worked with the Natural Heritage Endangered Species program to develop a plan to not interfere with two endangered species, a type of freshwater mussel as well as a dragonfly that frequents the area. This will involve ongoing monitoring by SOLitude.
“It’s really hard to tell how long the treatment will last…we’re hoping for multiple seasons,” explained Meringolo. “But, phosphorus will leak back in through the watershed.”
Problems with the water quality in the West Monponsett pond go back decades. In 1964, during a drought, the state legislature passed special legislation allowing the city of Brockton to draw water from Monponsett Lake via Silver Lake, Brockton’s primary water source.
This effectively reversed the natural direction of the water flow, leaving West Monponsett pond stagnant and an excellent source for phosphorus to grow. Soon, cyanobacteria blooms were frequent in the summer, limiting recreational activity on the pond.
Residents and interest groups debate the sources of the phosphorous. Everything from fertilizers that cranberry bogs use to human sources such as leaking septic tanks have been blamed, yet it’s likely that a mixture of several sources have caused the problem.
Hopefully this summer will be cyanobacteria free.