Beaches along Lake Champlain close due to toxic cyanobacteria blooms
By Zachary Matson
As water temperatures have increased in Lake Champlain, a spate of hot, sunny weather set the stage for dozens of harmful algal blooms throughout the lake, including ones that forced beach closures along New York’s shoreline.
Public beaches in Westport, Port Henry and Moriah faced closures in the past two weeks, and Vermont’s comprehensive blooms tracker has documented scores of HABs this month. Most of the blooms are small, considered generally safe, but some rated as “high alert” under Vermont monitoring standards, meaning they were more persistent and widespread. A high alert bloom was documented near the Westport boat launch on Wednesday.
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The above map shows harmful algal blooms reported to the NYS HABs site in early-to-mid July 2025. More information can be found on the DEC’s website.
Cyanobacteria, or blue-green algaes, starts to rise to the water surface and form green blooms around this time of year and persist into the fall. Torrential rainfall that forces a pulse of nutrient-rich runoff into the lake also exacerbates bloom formation.
“We have increased phosphorus loading, increased temperatures, increased flooding and all that creates a triangle of elements needed for these blooms that are happening,” said Julie Silverman, the Vermont-based Lake Champlain Lakekeeper.
Cyanobacteria can be toxic and harmful to human health, so scientists and health authorities recommend people avoid the blooms or recreating in the water around them.
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Matt Brassard, the Moriah town supervisor, said they closed the town-operated Bulwagga Bay Beach last week “out of an abundance of caution.” He said town lifeguards spotted a greenish tint to the water when they arrived for duty; Brassard and the town water supervisor took pictures and sent them to the state Department of Health. DOH confirmed that it was likely a cyanobacteria bloom, and Brassard closed the beach. After sending a water sample to a state lab in Albany, Brassard got the “all clear” to reopen the beach the next day.
“It’s so weather dependent,” Brassard said of the algal blooms. “If the wind doesn’t blow for three or four days and there’s no rain, it blows up like Miracle-Gro on your plants.”
The Port Douglas Beach in the town of Chesterfield and Ballard Park Beach in Westport have also closed in the past week due to cyanobacteria blooms.
The New York Department of Environmental Conservation’s HABs tracking map also lists numerous blooms along the state’s Lake Champlain shoreline. Far fewer blooms have been documented in the Adirondack interior so far this summer, though ones have been recorded in the past week at Little Tupper Lake in Hamilton County and Otter Lake in Oneida County.
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Photo at top: A cyanobacteria bloom along the rocky shoreline. Photo by LCC Monitor Nathalie Santerre. Courtesy of Lake Champlain Committee
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