Preston - A large part of the solution to the problems at Amos Lake lies beyond its shores, in what happens - or doesn't happen - on the lands and waterways around it.

That's the conclusion of a draft report on conditions at the 113-acre lake off Route 164, presented last week to members of the Amos Lake Association by the Eastern Connecticut Conservation District.

Plagued in the summer by thick mats of algae and invasive weeds, the lake has been on the state's Impaired Waters List since 2006.

District staff, with the help of about 15 association member-volunteers, began a study of the lake in 2012 that included water sampling and testing both in the lake and the streams that feed it. The district and the lake association have been working to find the sources and possible solutions to the problems that would get the lake off the Impaired Waters List. The study and development of an improvement plan are being funded with a federal Clean Water Act grant being administered by the state Department of Energy and Environmental Protection.

"It's not a one-answer question," Patricia Monahan, president of the lake association, said Tuesday. "But once we identify the sources, we can get all the key players together and coordinate a plan. Otherwise we're just spinning our wheels."

Jean Pillo, the district's watershed conservation coordinator, said the testing showed that high levels of nitrogen and phosphorous in a main tributary stream on the west side of the lake are providing the excessive nutrients that cause the lake to become choked with algae. The stream collects runoff from the commercial, residential and agricultural development in the Preston City area, she said. The polluted runoff is coming from lawns, parking lots, roadways and fields.

In addition, a wetland that would have filtered out much of those nutrients was filled in more than 40 years ago, with permission from state environmental regulators, Pillo said. The farmer who owns the property had used the filled-in wetland to expand his agricultural fields, she said, but that land is no longer being used. Restoring the wetland would in turn help restore the lake.

"We believe that would have a major impact," she said. "It would be expensive, but we think we could get funding, if we had the owner's permission."

The lake is further challenged by its naturally slow flow, she said. Water entering the lake takes about two years to circulate out, creating ideal conditions for algae to flourish unchecked. Lakeside cottages with failing septic systems may also be contributing to the problems, she said.

Invasive milfoil growing near the state boat launch is also harming the lake, crowding out native plants and impeding boating and fishing. Pillo said the conservation district is recommending that grant funding be sought to remove the milfoil before it spreads to cover the entire lake bottom.

"We think it should be taken care of now," she said.

Monahan said the study and plan will guide the association in working with the town and commercial, residential and farm owners in the watershed to take steps to reduce polluted runoff entering the lake.

"It will help us with our ongoing outreach and education projects, not only with the lakefront property owners, but with everyone in the watershed," she said.

She added that she has also enlisted Coast Guard Academy cadets studying civil engineering to help with the project, including presentations to association members about low-impact development and possible future assistance with the wetlands restoration.

Pillo said that over the next two months, analysis of the data from the water testing will be completed and the final plan finished, with a set of recommended projects included. After that, the association can work with the conservation district and the town to apply for grants to fund the projects.

"What they need is a road map," she said.

j.benson@theday.com

View the complete list of Connecticut waterways classified as impaired

Connecticut Impaired Waters

View the

complete list of Connecticut waterways classified as impaired.