GREENE – Allen Pond residents should notice the water in their backyard rising slowly, now that crews have completed repairs to the pond’s 19th century dam.

Volunteers wrapped up repairs to the dam Sept. 27, removing concrete forms. They’ve been letting the newly poured concrete set and cure.

“But it’s done now,” said Suzanne Rousseau, president of the Allen Pond Improvement Association. That group owns the dam.

“There’s no way of knowing just how long it will take before it’s filled up,” Rousseau said. “That depends on the weather, and if we get rain it’ll fill up even faster. But it’s on its way now.”

The dam has been in place since the 1850s, blocking the spring-fed Allen Stream. That stream flows northward into Leeds and eventually to the Androscoggin River.

Oak tree roots threatened to damage the structure’s western end. After some debate, the improvement association raised $3,000 to pay for the work and began looking for volunteers.

“If we hadn’t had the volunteers, it would have cost much, much more than $3,000,” Rousseau said.

Volunteers began letting the pond run off in August, keeping just enough water in the dam to keep the Allen Stream running. They began digging in September, building concrete forms, and they poured the new structure on Sept. 17, 18 and 19.

“It also gave all the homeowners along the pond the chance to clean up their beaches, so that was a side benefit, too,” Rousseau said. The 180-acre pond is rimmed by about 50 homes.

“We got a real glimpse of what our properties would look like when the pond level was down,” she said. “Without that dam, most people wouldn’t have a pond in their backyard. They’d have a little brook.”