OTISFIELD — A cofferdam on Pleasant Lake in Casco is apparently causing unstable conditions on the lake and on Parker Pond, an official said.

Signs have been posted in Otisfield and Casco warning: “Folks who are recreating on Pleasant Lake or Parker Pond should do so with caution. Water levels will be receding under the ice and may result in unsafe conditions in certain areas.”

The recently discovered fluctuating water levels have not only caused unsafe conditions for those venturing onto the ice but some camp owners have reported flooding on their property.

The new Pleasant Lake Dam, where the cofferdam is, regulates the water level of the lake, which straddles the Otisfield-Casco line, and Parker Pond at the southern tip of the lake in Casco.

Pleasant Lake has private camps, cottages and homes along it, as well as the Seeds of Peace International Camp on the western shore and Camp Arcadia for Girls on the eastern shore, both in Otisfield.

Last year, each town approved spending $250,000 to replace the failing dam, and work began in October, a month later than planned. A cofferdam — a watertight enclosure pumped dry so the dam could be built below the water line — was placed on the south side of Route 121.

The unstable condition appears to have started when the Maine Department of Inland Fisheries and Wildlife built a second cofferdam on the north side of Route 121 to install a pipe to allow fish to pass while the dam is being replaced, Otisfield Selectman Hal Ferguson said.

With warm temperatures and snow buildup, the water began to rise and back up, Ferguson said, flooding some camp properties.

Ferguson said some sandbags have been removed from the state’s cofferdam and water is being diverted through a makeshift passageway to stabilize the levels in the two water bodies.

Ferguson said officials are doing everything they can to warn people to be careful if they are on the ice.

Besides the problem of rising water levels, the project is overbudget by about $38,000 for each town, mostly because of a late start to construction, Ferguson said.

“We had originally wanted to start at the beginning of September, but we didn’t start until the second week of October,” he said.

Besides waiting for a state permit to remove tons of sand and silt built up above the old dam, workers ran into a very old dam under the existing structure and had to shovel snow by hand. It was hoped the dam would be finished in December.

Otisfield will pay its share of the overrun from the $250,000 bond, $5,000 from the contingency fund and $10,000 the Pleasant Lake and Parker Pond Association donated to each town for the overrun.

Otisfield also has $57,500 from the sale of Lot 4 at Heniger Park, if necessary. All of the money is available to be used at the discretion of the Board of Selectmen, Ferguson said.

ldixon@sunmediagroup.net