Restoration Project Will Clear Choked Pond, Help Clean Water

By: Tim Wood

Topics: Conservation , Environment

The pond in front of Agway is in the process of being restored after losing half of its open water area over the past few years to siltation and invasive plants. TIM WOOD PHOTO

CHATHAM – A sign posted at the front desk of the Chatham Agway store reassures customers that the ducks that live on the pond in front of the Main Street garden center aren't being harmed during restoration work on the small body of water.

People still ask about the ducks, store employees say, but in fact, although they remain on site during the work, it's had little impact on them. When heavy equipment is operating, the ducks tend to gather on the opposite side of the pond. On Monday the ground was too wet for the equipment to operate, and the three ducks that call the pond home were swimming contentedly, exploring the areas where their home has changed.

The goal of the project now underway at 1005 Main St. is to remove non-native plants and dredge sediment that has been slowly choking the pond over the past few decades. Just since 2016, about half of the open water area of the pond has been lost thanks to sand and silt deposited by stormwater runoff and the proliferation of cattail and other invasive species.

It may seem like one big mud pile now, but when it is completed within the next week or so—depending on the weather—the pond will be deeper and its banks seeded with native grasses and wildflowers that will serve as habitat for wildlife.

“It should provide very good pollinator habitat,” which in turn will help attract birds and other species, said Jen Crawford. The Sandwich company she and her husband Nick own, Crawford Land Management, is overseeing the project for property owner Sam Streibert.

The project will also contribute to cleaning up the Oyster Pond watershed. The pond serves as a retention area for runoff from Lime Hill Road and Main Street, and through a culvert under Linden Tree Lane is connected to the Oyster Pond system to the southeast. Making the pond deeper, thus able to retain and treat more water for longer periods, and installing a silt fence across the culvert will help improve the quality of the water flowing from the pond into the watershed.

According to Streibert, years ago the area was an open field when the Small family had a farm stand at the location. Much of the area to the south was farmland known as the Doane estate, he said. At some point drainage from Main Street and Lime Hill Road began to fill the area and it became a vegetated wetland, and the installation of weir and culvert led to its evolution to an open water pond.

It's likely that silt from runoff has been filling in the pond for years. Tests indicate that there is a silt layer about three feet deep at the bottom of the pond; below that is a layer of clay, which insulated the pond from groundwater.

The silt has raised the level of the pond, and Streibert said that he's noticed over the past few years that cattails have populated first the western side, and then the eastern side of the wetland. This happened fairly rapidly; Crawford said that aerial photos confirm that cattails first appeared in 2014, and between 2016 and 2018 about half of the open water area has been lost. She said the sediment buildup provided the ideal conditions for the cattail to proliferate.

Other invasives, such as bittersweet and gray willow dominated the edges of the pond.

Without active management, the open water area will continue to shrink due to encroachment from cattail, which will in turn reduce the pond's ability to manage and filter stormwater runoff, according to a report filed with the conservation commission, which approved the project.

It's uncertain whether the project will improve the quality of the water moving out of the pond into the Oyster Pond watershed, said Natural Resources Director Robert Duncanson. The series of ditches that channel the pond's water lead right into Oyster Pond at Oyster Pond Furlong, and while increasing the depth may help the water quality by retaining runoff longer, “I'm not ready to make that call,” he said.

Along with removal of the cattail, approximately 18 inches of sediment will be dredged from the bottom of the pond. Already about 300 tons, or 200 cubic yards, has been excavated and disposed of.

“It's a really messy process,” Nick Crawford said, especially given the recent rains, which made the whole operation a whole lot muddier.

When completed, the east end of the pond, the deepest portion, will have a depth of about three feet.

A forebay—an area of rocks meant to slow down running water—will be built to trap sediment from runoff coming off Lime Hill Road. That should help prevent the pond from filling up with sediment again, at least in the short term; long term monitoring will be necessary to make sure the pond doesn't fill in.

Likewise, for several years it will be necessary to monitor the native plants that will populate the pond's banks. Some have already been seeded and are covered in erosion control netting. This is a good time to get the seed established, Nick Crawford said.

“A lot of wetland seeds need to go through a freeze/thaw process to germinate,” he said. Eventually the diverse native populations will naturally sort themselves out and find the upland and wetland where each species does best, said Jen.

“The more diversity of species we introduce the better positioned they are for the future,” she said.

Streibert said he hopes to work with the Massachusetts Department of Highways to eliminate the runoff from Route 28 that goes into the pond.

He also hopes to add more ducks to the pond's population, and said anyone who wishes to donate ducks can contact him through Agway. At one time there were more than a dozen. The waterfowl were there when his late wife, Barbara, established the Greensleeves Garden Center in 1994. She added to the numbers, picking up ducklings that were shipped to the post office at 5 a.m. at one time, he recalled. She installed a pen and began to raise them.

“They'd follow her around,” he said. An incubator was set up inside the garden center. A customer donated a model of the Chatham Coast Guard Station and Lighthouse and the ducks became popular with customers, and remained so when Agway opened.

When the project is completed, the pond, as a whole, will have a larger capacity to retain stormwater—and accommodate more ducks.