Halifax pond declared off-limits due to blooming blue-green algae

Blooming blue-green algae has put an end to summer fun at two public beaches and a boat ramp at Halifax’s West Monponsett Pond and will probably keep the pond’s recreational spots off limits for the rest of the season, as it has in recent summers, officials say.

Shoreline homeowners have been strongly cautioned about pond use due to harmful health effects linked to the algae, also known as cyanobacteria. Nobody seems to be swimming in the pond now or water skiing, but a few continue to boat.

“We’ve closed the beaches, but if someone who lives on the pond wants to go out on the water, it’s not like we’re going to fine them or put them in jail,” Town Administrator Charles Seelig said last week.


West Monponsett Pond’s woes with the cyanobacteria are obvious even to the untrained eye. Thick mats of algae choke coves and color the water pea-soup green, while emitting a foul odor. Summer is peak growing time.

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“The Fire Department gets calls about gas odors and comes out to check for leaks, but the odor is from the algae,” said Cathleen Drinan, the local health agent.

Odor is only part of the problem. If allowed to sit on the skin, the blue-green algae can cause rashes, hives, and blisters. Inhaling droplets of it can result in runny eyes, infected sinuses and ears, sore throats, and asthma-like symptoms.

Swallowing it will guarantee some major digestive discomfort, according to state health officials. Pets have been known to die from ingesting it, and children can become quite ill.

“Children have smaller bodies and tend to splash and swallow water,” Drinan said.


The state Department of Public Health has tested West Monponsett water weekly in the summer since 2009 “due to a history of cyanobacteria blooms and the opportunities for exposure through recreational activities,” said Martha Steele, deputy director of the agency’s Bureau of Environmental Health, in an e-mail.

Drinan said the state Department of Environmental Protection has been studying pollution in the pond, focusing on the Morse Bros. bogs because phosphorus in fertilizer used for growing is a primary nutrient for cyanobacteria.

“DEP is working with bog owners on best management practices, like creating a lagoon to drain the water into, so the fertilizers can sit,” Drinan said. The agency is also producing regulations limiting the amount of phosphorus that can be released daily.

Drinan posted West Monponsett’s public beaches and boat ramp as closed June 14, when cyanobacterial levels considerably exceeded acceptable thresholds. Beaches have been closed for most of the summer for the past three years. “The first year, we thought it would go away with the cold weather, but the level stayed high through December,” he said.

Officials want to treat the pond with aluminum sulfate, proven effective in eliminating the algae, but the presence of an endangered mussel and dragonfly larvae has delayed that. The state Natural Heritage and Endangered Species Program, a division of the Department of Fisheries and Wildlife, must approve plans for treatment and species-monitoring.


“It was only last month that we got the OK from the Natural Heritage people,” said Seelig. “The problem is we’re too far into the season. The best time to treat is April or May, so the plan now is to treat the pond next spring.”

West Monponsett Pond resident Suzanne Lillie said she still boats on the pond — but cautiously. “You have to be worried about being splashed while you’re out there,” she said. “It’s not as pleasurable as it used to be. I’m also disturbed by the water’s appearance.”

Residents on East Monponsett Pond, connected to West Monponsett Pond through a culvert, fear the algae will eventually foul their waters, too.

“I’ve physically seen the stuff coming into East Pond through the culvert,” said East Monponsett Pond resident Mike Driscoll.

The natural water flow is from East Monponsett to West, but the city of Brockton, allowed by state law to use the ponds as part of its drinking supply for 10 months a year, draws water in the opposite direction, causing West Monponsett to flow east.

“You could see the green stuff floating into East Lake when they’d draw,” Driscoll said. “You’ve got this body of water that’s bordering on poisonous and you draw it into a clean lake. That’s crazy.”

Seelig agreed that Brockton’s early-summer water diversion poses a risk of algae pollution in East Monponsett. “The problem is the tail end of the withdrawal overlaps with the algae season,” Seelig said. “I suppose we could sit down and try to get them to stop sooner, but how do we set a date?” — since the appearance of the algae can’t be predicted ahead of time.

Drinan said the long-term solution is elimination of the algae’s nutrient sources. Failed septic systems, storm water run-off carrying fertilizers and animal waste, and bog operations contribute phosphorus.

Residents on both ponds are organizing the Monponsett Watershed Association, Drinan said, to work on long-term solutions. The Pembroke Watershed Association, which has successfully cleaned up that town’s ponds including two with cyanobacteria, serves as inspiration and has offered to help.

Drinan said her fledgling watershed group is happy for the assistance, “but it was a little discouraging to hear they started out eight years ago.”

Christine Legere can be reached at