Thick Algae Turns Lake 'Lilli' Into Pea Soup

Imagine living on a scenic lake with towering cliffs, wooded shorelines and bald eagles. The only problem is, every summer the water turns green, thick with algae. State and the federal governments are working to fix this problem on Lake Lillinonah.  But as WNPR’s Nancy Cohen reports some residents say it’s taking too long.

On the western edge of Connecticut, Lake Lillinonah encompasses 1,900 acres, making it one of the biggest lakes in the state. But Lake ‘Lilli’ as it’s known, was once a free-flowing 12-mile stretch of the Housatonic River. In 1955, Connecticut Light and Power dammed it and the water has generated electricity ever since.

Scott Conant is piloting his pontoon boat north on Lake Lillinonah. Conant has lived here with his family since 1984.

“We love the scenery. We love how it changes every day. Every day is a different view from our house.”

In places Lake ‘Lilli’ runs narrow and fast like the river it was born from. But Conant says in the late summer when the algae blooms many people won’t swim or water-ski.

“Your spray from your ski is green. Like soup, its thick and your legs turn green. It’s disgusting is the best term for it I guess.”

Excessive amounts of phosphorus in the lake act as fertilizer and help the algae grow. It’s a problem the U.S. Environmental Protection Agency has known about since the 1970s. But both federal and state government are still working on the problem.

According to the Department of Environmental Protection, about 42% of the phosphorus load comes downstream from New York and Massachusetts. Another 40% is from storm-water runoff in Connecticut. And the rest comes from sewage treatment plants in the state. All in all a complex problem.

“It’s really stringy.”

Greg Bollard is taking a sample of algae that’s floating, like thick scum, on the surface

“It’s like the consistency of seaweed, but it’s not seaweed. This is algae.”

Bollard is one of several volunteers who monitors the lake for a long term study on water clarity, led by Fairfield University Biology Professor Jen Klug. The algae is not only a problem for people, it also hurts the lake. Klug says the dead algae mats on the surface eventually sink to the bottom where they’re consumed by bacteria, robbing the ecosystem of oxygen.

“You’ve got all this food going down to the bottom of the lake, feeding the bacteria, the bacteria using up all the oxygen and there’s no oxygen left for anyone else.”

Back on Lake Lillinonah, the boat passes under a bridge in New Milford where the Still River empties into the lake. Danbury Sewage Treatment discharges millions of gallons a day of treated effluent into a brook that feeds the Still River. Greg Bollard, who is with Friends of the Lake, wants the state to clean it up.

“It’s a very slow moving machine. We have added enough awareness, enough attention to it where I think we have made some progress of lately. But it’s not enough.”

But the D.E.P. says it is making progress. Two years ago, the agency negotiated a consent order with the city of Danbury which operates the sewage plant. Paul Stacey of the D.E.P. says not only has the plant voluntarily reduced the amount of phosphorus it discharges, the amount is even lower than the targets set by the agency.

“On the average, they have been meeting the requirements of the consent order and doing it pretty well.”

Danbury has been meeting the deadlines set by the consent order. But Stacey says the D.E.P. is about a year behind.

“It’s really, you know, not uncommon that we will get behind just because of staff resources, but I think the important thing is that the city of Danbury is not behind in their commitment.”

Stacey says besides phosphorus at sewage treatment plants, a bigger problem, that’s even harder to control, is runoff from farms, streets and homes. 

“That’s a much more difficult proposition because it requires very cost efficient types of management practices. And it also requires in many cases individual homeowners to do something that they may not be aware of and they may be reluctant to do, in any case. In terms of making Lake Lillinonah not green anymore, or whatever the objective might eventually be, it’s going to be really hard to get to that point just by managing sewage treatment plants. But I think it’s an important first step.”

Friends of the Lake is trying to educate homeowners on Lake ‘Lilli’ to reduce their use of chemical fertilizers. But the problem is bigger than lakeside homes. Fairfield University Professor Jen Klug says because Lake ‘Lilli’ is a dammed up river, water doesn’t flush out as quickly and sediments that contain phosphorus stay in the lake. And she says about 1,400 square miles from three states drain into the lake.

“Quite frankly, it’s never going to be a crystal clear lake. The fact the water that’s draining in a huge percentage of northwest Connecticut  and Massachusetts, it’s all going to collect here. And that water’s never going to be perfectly clean no matter what we do, but we can certainly make it better.”

For WNPR I’m Nancy Cohen.