Milford to demolish the Great Beaver Dam in Medway to stop flooding

MILFORD, MA — A group of large, industrious semi-aquatic rodents has launched a complex legal and environmental project in Milford.

A group of beavers recently built a large dam on a culvert that runs under Alder Street in Medway, just west of I-495. The dam caused Stall Creek to overflow, flooding Maple Street in Milford, which is about a half-mile from the dam as the crow flies.

Milford Town Engineer Elizabeth Mainini went before the select committee on Monday to request permission to contact the Medway Conservation Commission about removing the dam. Medway requires Milford to take responsibility for any damage caused to Alder Street or the culvert while carrying out the work. Milford had already received an emergency evacuation permit for beavers and muskrats from its neighbor to the east.

Although small — typically about 3 feet long and weighing up to 65 pounds — compared to the size of municipal government, beavers regularly cause headaches in communities across the state. In 2021, a beaver dam ruptured near Warren, flooding the entire downtown area.

Massachusetts has strict beaver laws (yes, that’s what they’re called) that specify how and when beavers can be captured and where they can be relocated. Local boards of health are the only entities authorized to issue emergency collection permits outside of the annual trapping season, between November and April.

Trapping and removal is often the best solution to a beaver problem, according to national wildlife experts. The destruction of a dam can prompt beavers to simply rebuild, and they can do so in a matter of hours.

According to Mainini, the city has already captured and removed the beavers, leaving their empty dam in place. The structure, which is about as tall as the road, can still cause flooding if vacant, she said.

The city will also need to hire an environmental consultant to oversee the deconstruction of the dam. If removed too quickly, water accumulated behind the dam could cause more flooding, Mainini said.

“If you take out too much too quickly it can cause big damage,” she told the select committee.