At the end of Kondelin Road, the waist-deep pond they created two years ago by damming a culvert at the headwaters of Wolf Trap Creek stands frozen.
The lodge of the endearing, if exasperating, animal civil engineers - thought to be four to eight beavers from two generations - is barely visible from the road. At this time of year, they would be inside, waiting out winter's end, munching the fall harvest and the adults typically making a third generation.
On higher ground, human plans are afoot to allow the beavers to stay in the pond by making it smaller. This would prevent instances of flooding that previously have endangered the cold storage facility adjacent to the creek.
The Economic Development and Industrial Corp., the public agency that manages the Cape Ann Industrial Park, has initiated the action, hoping to stop more flooding.
It has contracted with ENSR, a global environmental engineering company, which has subcontracted with Beaver Solutions, a company specializing in "beaver/human conflicts."
For now, the Economic Development and Industrial Corp. has budgeted $17,400 and directed its hired experts to prevent further flooding without displacing the beavers - or worse - killing them.
The goal, said agency executive director Alan Hagstrom, is to "live happily ever after with the beavers."
That, of course, assumes the experts' counter-beaver technology works. A lot depends on the beavers, too.
The monogamous rodents with the big incisors and flat tails are a much-studied species, especially since they have reappeared in locations from which they were hunted, trapped, or displaced by civilization.
It has been found, for example, one beaver is capable of felling more than 200 trees a year for food and construction of dams that change wetlands into ponds - as they have done in Hamilton and Gloucester, and even recently in the Bronx River in New York City.
In Hamilton, the dams created flooding problems along the Miles River severe enough to warrant the granting of trapping permits.
The extreme strategy brought protests; with even the permitting authority, the Hamilton Board of Health, conceding trapping at best will only give the town "a chance to get ahead of the problem, at least for a while," as board Chairman Steve Druschel told the Salem News earlier this winter.
The reappearance of a beaver in New York City, once so important there they were exalted on the city's official seal, brought rejoicing, a sign of the success of the clean-up of the Bronx River where "Jose," as the beaver was named - likely a 2-year-old setting out on his own from the family lodge in Westchester County - was seen settling in.
At the age of 2, moving downstream is typically what they do.
"In spring," said Beaver Solutions president Mike Callahan, "the 2-year-olds break away from mom and dad and start their own lives." At this stage, he described them as equivalent to college kids.
Anticipating this and other colonizing behaviors, including canal building in spoke patterns, ENSR/Beaver Solutions has proposed restoring the flow through the Kondelin Road culvert, and deceiving the beavers into wasting their efforts by rebuilding in the wrong places.
Callahan said he was confident the beavers would remain committed to damming the culvert. Keeping them busy at what the technology endeavors to make a fool's errand is the essence of the strategy.
"They love culverts," he explained. "Very little work, big dam."
The agency yesterday released a copy of the plan it was submitting to the Conservation Commission, which governs wetlands activity and is expected to hold a public hearing later this month.
At its essence, the plan is this:
First, the dam at the culvert would be removed in stages along with the "several cubic yards of gravel" deposited by the Department of Public Works in 2005 in a failed attempt to deter the beavers from rebuilding their dam.
The dam had been mysteriously destroyed one night and the pond water liberated at once, which roared down Wolf Trap Creek flooding homes in Manchester along its banks. One home suffered more than $50,000 damage.
ENSR noted the stone put down by the Department of Public Works "only served to reinforce the repaired beaver dam at the culvert."
After the culvert is cleared, a trapezoidal protective fence will be installed. Its purpose is to keep the beavers from the culvert and redirect their instinctual rebuilding efforts to points of lesser effect.
But it is expected the beavers will be able to create some damming, which is why ENSR also proposes to install a "flexible pond leveler," a kind of overflow pipe to the culvert, surrounded in metal grating that would keep the pond at a set level.
Finding the right level is key, according to the draft plan.
"While Beaver Solutions believes these devices can maintain the water level at the Kondelin Road culvert," ENSR wrote, "the devices cannot prevent the beavers from building dams upstream and downstream of this pond. The more the Kondelin Road impoundment is lowered," the company noted, "the greater the risk of new problematic dams."
Should the beavers follow their preferred emigration route downstream, the problem would quickly become Manchester's. The town line is barely 100 yards south of Kondelin Road.
If benign technology fails, conservation agent Nancy Ryder said the next step would be up to the property-owning Economic Development and Industrial Corp. . "Whether it be beaver trapping or dam control is up to the EDIC," she said in an e-mail response.
Moving them to a less problematic location is not an option. Beavers are highly territorial, and frequently do not survive forced relocation.