State lakes take a break from toxic blue-green algae

Toxic blue-green algae in local lakes popped up as normal this summer, but fewer blooms in recent years have left researchers searching for answers.

Blooms of cyanobacteria, or blue-green algae, were reported on a number of lakes, though Candlewood Lake continues to be relatively clear. The blooms have become a concern in recent years as more research is uncovered about the potential toxicity and dangers the cyanobacteria can pose to animals and people, ranging from skin irritation to death.

“Lake Zoar is starting to show some pretty interesting things again,” said Edwin Wong, a Western Connecticut State University associate professor studying the cyanobacteria’s toxins.

Wong leads a research team that collects and analyzes water samples from beaches on Lake Zoar, Lake Beseck and Candlewood. The weekly tests wrapped up for the summer last week.

Numbers for Jackson Cove in Oxford and Eichler’s Cove in Newtown, both on Lake Zoar, have had higher levels of toxins in recent weeks, though still below the new federal limit of 8 parts per billion.

The limit changed last year from 4 parts per billion.

“There’s always concerns about low-level exposure,” Wong said, adding there’s research showing cyanobacteria may cause dementia or brain damage.

Blooms have also been reported on Bantam Lake, Rainbow Reservoir, Lower Bolton Lake, Middle Bolton Lake, Lake Lillinonah, West Thompson Reservoir, Lake Pocotopaug, Roseland Lake, Long Meadow Pond and numerous small ponds, said Will Healey, a spokesman for the state Department of Energy and Environmental Protection.

“This year is about the same as last year and about what we have been seeing for the last several years,” Healey said.

Research is still evolving on what causes the blooms, but weather, nutrients entering the water and the type of body of water are all factors scientists suspect for why some spots continue to see blooms while others are clearing up.

The blooms tend to appear when the summer is hottest and there is little breeze. The cyanobacteria thrive in these conditions because they can regulate their buoyancy within the water column and soak up the sun near the surface.

The big outstanding mystery is why last year was so quiet in Connecticut despite lakes across the country resembling pea soup and dogs dying shortly after swimming in blooms.

“Last year in 2019, everyone went quiet,” Wong said. “We’re going to dig deeper into what happened in terms of activity.”

Coronavirus

Another unknown is whether the coronavirus has had any impact on this year’s blooms.

“There may be reports from lakes that would not have been reported due to more people recreating outdoors,” Healey said.

Wong said there’s a chance the virus could have altered people’s behaviors that would have an indirect effect on the blooms in either direction.

He suggested people might be fertilizing their lawn more since they are home, which could increase nutrients entering the water through runoff, or they may be occupied and not tending to their yards as much. Being home more might also put more strain on people’s septic systems, another way for nutrients to enter the water.

These nutrients are a main food source for the cyanobacteria.

Wong said he hasn’t seen much of a difference in toxin levels for beaches around Candlewood Lake that have opened to visitors, compared to those that have remained closed to prevent the spread of the coronavirus.

Downriver

Lakes along the Housatonic River have reported blooms for a few years now, including Lillinonah and Zoar.

DEEP removed Kettletown State Park, which sits on Zoar, as a designated swimming area last year as a precaution because of the constant blooms.

Kettletown’s swimming area and other coves are more at risk because it’s harder for the water to move around in the outlets, which can also better trap what’s coming down stream.

Being on a river also means a greater surface area for runoff to enter the water compared to a lake. Agriculture, plant or septic failures and lawn care upstream can play a bigger role on these lakes, which are more like widened sections of the river than a standalone lake.

Lake Zoar is also behind a dam and prone to collect more of what’s traveling in the water.

H John Voorhees III / Hearst Connecticut Media Professor Ed Wong, of Western Connecticut State University, takes a water sample from Lake Zoar at Jackson Cove Park in Oxford on Wednesday. Wong is monitoring cyanobacteria (blue-green algae) in the lake.