Susan Landry remembers a bar of soap that sat ready on her family’s dock on Highland Lake when washing and shampooing in the lake was part of the daily ritual.

That was long before words such as “invasive species” and “water quality” became part of the common vocabulary.

“We just didn’t know any better,” said Landry.

the 1980s the lake, located in Windham and Falmouth, had grown so murky its population of brown trout was threatened. The lake wound up on the state and federal “impaired lakes” lists in 1990.

This month — after 20 years and an intense cleanup effort by residents — the lake has been officially removed from the lists.

“We are proof that you can put out a lot of effort and turn things around,” said Landry.

Landry, a lakefront resident and president of the Highland Lake Association, said the lake is as clear today as any lake in the Baxter State Park region.

“You can see the bottom — and you could never see the bottom before,” said Landry.

The water quality problems were directly tied to soil erosion from development around the 623-acre lake, which is only seven miles from downtown Portland. Some 300 houses occupy its eight miles of shoreline, and 600 more are located within its 8.4-square-mile watershed.

As land was developed and forest removed, phosphorus-laden sediment entered the lake’s feeder streams. The phosphorus fertilized the lake, allowing algae to grow, reducing water clarity and dissolved oxygen.

The polluted runoff was coming from multiple sources across the watershed.

“Part of the problem with runoff is it is very hard to point and say ‘there it is’,” said Betty Williams, project manager at the Cumberland County Soil and Water Conservation District.

State environmental specialists determined the annual load of phosphorus entering the lake needed to be reduced by about 24 percent in order for the water to meet state standards.

A watershed survey identified the major sources of erosion, which included private camp roads, town roads and residential lots. Some $924,000 in federal, state and local grants was used to carry out erosion control measures, such as regrading roads around the watershed.

More than 50 landowners adopted other anti-erosion practices, such as building rain gardens and reducing lawn fertilizers. The Highland Lake Youth Conservation Corps cleaned out ditches, shored up culverts and planted thousands of buffer plants.

“Everybody pitched in and that is what makes it work,” said Williams.

Don Kale, a DEP watershed planner, said a long-term effort by residents to document the water quality in the lake also helped remove it from the list.

“A volunteer group had been monitoring the lake for close to 20 years,” he said.

Their data, which included special testing by several universities, showed a long trend of water quality improvement.

Highland Lake was the only lake dropped from the state’s list of 32 impaired lakes this year. Great Pond in Belgrade was added to the list.

Landry said the lake’s water quality will always be fragile. Efforts to control soil erosion in the watershed will need to continue to keep the water clean and clear, she said.

“It will never be cured just because of everything going on in the environment,” Landry said.

Staff Writer Beth Quimby can be contacted at 791-6363 or at:

bquimby@pressherald.com