Beaver dam flood woes hard to ignore

A brook flooded an area in north Lexington off Bedford Street during recent torrential rains, threatening to gush into the sewer system and cause overflows of raw sewage. The problem: An enterprising beaver was constructing a dam. The solution: The beaver was trapped and killed.

Beavers like the 50-pound male trapped last month are the stuff of suburban legend, as the furry rodents migrate into congested neighborhoods and dam up brooks and streams.

"I think one of the things people need to remember is we don't really have predators that control beaver any more, such as wolves, so they're not being killed naturally," said Patricia Huckery, northeast district manager for the Massachusetts Division of Fisheries and Wildlife. "The only option is management."

Wildlife management can mean extermination, but there are other options under the law that have been used in the western suburbs.

State officials recommend relieving flooding caused by beavers by breaching their dams. One technique includes fencing that impedes reentry to the area and rerouting water flow underground or through pipes so the beaver cannot hear the tinkling, running-water sound that attracts them to a site to build a dam. Or residents can take the wetlands attitude to leave it to beaver.

Along with Lexington, Concord and Bedford have had enterprising beaver populations in recent months. Sometimes the animals are welcomed, but other times not, as they cause flooding that can become a public health problem or inflict property damage.

Stanley J. Sosnicki, Concord's environmental health inspector, said while beavers can be a nuisance, many residents have learned to live with them.

"I'd say they're a net plus," Sosnicki said. "Most people around here are used to wildlife, and they tend to respect them."

On the plus side, beavers create wetlands by damming streams and forming shallow ponds.

The wetlands provide a habitat for diverse plants and animals, such as deer, bats, otter, herons, waterfowl, songbirds, salamanders, turtles, frogs, and fish. The wetlands also control downstream flooding by storing and slowly releasing storm water. They also remove excess nutrients, toxic chemicals, and sediment, and can recharge groundwater.

This is no solace to the homeowner with a flooded basement or the school child trying to navigate a street flowing with raw sewage.

The problem in Lexington occurred off busy Bedford Street between Ivan Street and Hadley Road. The beaver dam on Simonds Brook had caused water to run to the tops of sewer manholes.

John Livsey, the town engineer, said while the flooding did not overwhelm the sewer system, it could have if action had not been taken. The town hired a licensed trapper, who snagged the beaver on Dec. 24.

Bedford did the same, issuing a permit earlier this month to a trapper to catch a beaver on Veterans Administration property, according to Bedford's health agent and inspector, Joseph W. Knotts, who said he issued seven such permits in 2008.

In Concord, a beaver dam flooded the area last summer where the Police and Fire Departments are located, as well as the neighborhood across the street. In that case, the beavers were trapped and killed, and the dam removed, Sosnicki said. But neighbors living on Spencer Brook Road have decided to leave alone the beavers that periodically build dams on Spencer Brook and flood the area, he said.

Sosnicki said he issued three or four permits last year, and believes the beaver population is growing. "We're seeing more and more of them," he said. "The area's just conducive to beavers. We have a lot of wet areas."

No one knows for sure how many beavers there are across the state or whether their numbers are growing or shrinking, according to Laura Hajduk, the state wildlife agency's furbearer biologist.

Because of overzealous hunting, beavers were absent from Massachusetts from the late 1700s to the early 1900s, when they started making a comeback after farmers abandoned their fields for city jobs or moved to more fertile ground in the Midwest, according to the state wildlife agency's website.

By the early 1990s, the beaver population statewide was estimated at a little more than 22,000.

In 1996, voters passed a ballot question banning leghold traps, deemed to cause pain to snared animals, and the beaver population soared to an estimated 70,000.

And then, in 2001, another law went into effect that gave local health boards - and not the state wildlife agency - jurisdiction over emergency licenses to trap animals considered a public health threat or cause of severe property damage. While hunters had been reporting their harvests to the state wildlife agency, now there is no way to keep track of how many are killed, Hajduk said.

Still, beavers are likely to continue to venture into suburban living until the habitat becomes too developed.

For instance, Christine Connolly Sharkey, director of Health and Human Services in Arlington, said she has heard no reports of beavers in town since she started working there in 2000.

Donna Moultrop, Belmont's health director, said the only beaver report there in recent memory turned out to be an unfounded rumor.

Connie Paige can be reached at connie_paige@yahoo.com.