The aging dam that controls the water level in Maranacook Lake — but hasn’t been doing a great job of it — soon could be undergoing some improvements.

That dam is at the outlet of Maranacook Lake, near the Winthrop Town Beach. But the lake stretches from Winthrop to Readfield, and taxpayers from both towns would cover the bill for any repairs and renovations.

As both towns begin preparing next year’s municipal budgets, a special committee that includes Readfield and Winthrop residents soon will seek bids for a construction project that has been in the works since 2013 and will cost an estimated $237,000. That project would repair parts of the dam that have deteriorated while also improving its ability to release lake water quickly into the outlet stream.

Both towns already have raised some of the money for the work, and the dam committee is asking them to raise the remainder in the 2017-2018 fiscal year.

Based on how much lake frontage is in each town — 10.2 miles in Winthrop, 11.6 miles in Readfield — Winthrop would pay for about 47 percent of the proposed work and Readfield would pay for about 53 percent, according to Wendy Dennis, chairwoman of the dam committee and a lake scientist with the Cobbossee Watershed District.

In 2006, Winthrop and Readfield became co-owners of the dam after its former owner, Carleton Woolen Mills, had gone bankrupt a few years earlier, Dennis said. The dam was built into its current form in 1995, but it has deteriorated in the last 20 years and has proved itself incapable of letting water out of the lake fast enough to blunt the effects of flooding, Dennis said.

In the spring, Dennis said, lake levels can rise up to 2 feet, sending water onto lawns, causing erosion and damaging property such as docks.

The current dam lets water out through a gate that’s 5 feet wide, according to Dennis. The proposed modification would expand that width to 20 feet. The new gate also would be deeper than the current one, making it easier for the dam’s operators — currently the Winthrop Public Works Department — to release water ahead of rainstorms or spring melting.

While those improvements would not stop flooding, Dennis said, they would reduce the number of days it takes lake water to return to its normal level after a storm. According to hydrological modeling, a rainstorm that now would raise the lake level more than a foot and take two weeks to dissipate would, with the new dam, raise levels less than a foot and take about five days to dissipate, Dennis said.

“In between storms, it will also allow us to adjust lake levels to whatever is beneficial for that time of year,” Dennis said. “For summer, we could make it high enough for boating but not high enough that the waves create erosion. Some residents want more beachfront, but right now we can’t alter levels to reach those objectives.”

The project also would stabilize the dam by replacing concrete that has deteriorated over the last 20 years, Dennis said.

Tom Heiss, whose Winthrop home looks out onto the dam, said he has witnessed the deterioration of that concrete first hand. He and his neighbors also have experienced the flooding that comes with some seasons, and he has lost several feet of property to erosion.

Heiss, who also sits on the dam committee, said one reason for area residents to support the repair now is to prevent the deterioration from continuing, averting the risk of a serious breach

“I didn’t want to see what’s happened in California happen here,” he said, referring to a recent scare in which 200,000 people were ordered to leave their homes in Oroville, California, after a hole was spotted in the spillway at a reservoir and officials grew concerned about a 30-foot wall of water being unleashed on the nearby homes.

Such a large disaster would not be possible on Maranacook Lake, but Dennis said the costs to repair the dam will only grow with time.

The dam committee probably will seek bids for the work in early March, Dennis said. If Readfield and Winthrop raise the remaining money for the dam project this spring, she said, construction could begin as soon as July and take three to four months.

Charles Eichacker — 621-5642

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Twitter: @ceichacker