Dredging continues at Bare Hill Pond. A loader fills a dump truck with dredged up mud. Reducing the organic matter in the pond should result in fewer weeds next summer. This view shows the town beach looking toward Blueberry Island. (Photo by Lisa Aciukewicz)

A flock of gulls hop and peck their way across the mud flats, feasting on mussels. A huge yellow excavator looms over the muck like a brontosaurus looking for lunch. Clearly, some changes are under way at Bare Hill Pond.

The Bare Hill Pond Watershed Management Committee has hired CRC Company of Quincy, Mass., to dredge out silt that has accumulated in the swimming area. Dredging began the week of Dec. 12 and is expected to cvontinue for two or three weeks, according to Bill Johnson, the selectman who acts as liaison to the pond committee.

"The goal is to be done by the end of December," Johnson said.

Johnson, who is also a former member of the pond committee, said the dredging will serve three purposes. First, it will hinder weed growth by removing soil in which the weeds root, taking the bottom of the pond down to a base of glacial till.

Second, dredging will remove the benthic barrier that was installed in 1984 to suppress weeds. The barrier, now covered by silt, is no longer effective. Worse, according to Johnson, the barrier has become a hazard because its raveled edges could trap a swimmer's feet.

And third, dredging will increase the depth around the raft, where Johnson says it is now almost too shallow for diving.

Bruce Leicher, chairman of the pond committee, called the process "an example of government working well." He explained that six different permits were required for the work, but the various agencies all joined together for a single site visit in September. Among the agencies involved were the Massachusetts Department of Environmental Protection, the Army Corps of Engineers, the federal Environmental Protection Agency, and the Harvard Conservation Commission.

The permitting process usually takes six to nine months, Leicher said. But, with help from the project officer at the state DEP, permits were in place in time for the dredging to proceed this year.

Money for the project comes from a combination of state and local funds, Leicher said. A DEP grant covers 60 percent of the entire pond project, which includes other protective measures besides the dredging. The remaining 40 percent comes from local support, but not necessarily as cash. The DEP allows the pond committee to count the value of volunteer work hours toward the town's contribution, Leicher said, so the actual dollar cost to the town is quite small.

The Community Preservation Committee also provided funds for the project. A grant of $60,000 in CPC funds allowed the town to receive a $600,000 state grant.

"It's a great piece of leverage," Leicher said.

As the muck is dredged out of the pond, it is heaped in the parking area, contained by concrete barriers and heavy sheeting. Once the material has dried somewhat, Johnson says it will be trucked to the Department of Public Works site on Stow Road. The pond material will be combined with old road sand and compost to make "usable dirt," he said.

The pond committee originally intended to dredge the swimming area two years ago but was unable to do so because the six-foot drawdown in 2009 was not deep enough to expose the bottom of the bowl-shaped depression formed by previous dredging there. So the 2009 dredging operation was limited to the area around the boat ramp.

This year, the water level in the pond was drawn down seven feet, according to Leicher, six inches deeper than last year.

This year's drawdown was hindered by unusually heavy fall rains that refilled the pond even as the pump struggled to lower it. Then the power outage after the late October snow storm shut down the pump for five days, and the water level rose again. Constant backflow from the wetlands at Bowers Brook added to the problem.

The Conservation Commission has expressed concern about having the drawdown continue this late in the season. According to commission member Wendy Sisson, a late drawdown threatens turtles that live in the pond. They need to hibernate by burrowing into the mud at the bottom of the pond before a hard freeze. But if the pond's water level is constantly changing, they might be trapped out in the cold to die.

Sisson also pointed out that the prolonged pumping is expensive for the town because it uses a lot of electricity.

Conservation Commission chairman Paul Willard said the drawdown process should have a definite end date "so that everyone knows what it is and has to live with it."

Willard acknowledged that the containment area for the dredged material is working much better this year than it did in 2009.

"The water coming out of the containment area now is clean," he said, after a site visit to the pond.