The summer stench of Occom Pond will soon be a thing of the past, as the College and town of Hanover are undertaking a new initiative to improve the pond's water quality.
According to flow tests and core samples conducted over the last 25 years, the pond's water contains high levels of nitrogen and phosphorous. These chemicals cause unnatural algal blooms and, combined with a 15-foot layer of muck on the bottom and sedimentation from years of runoff, add to the pond's environmental problems.
"The pond is in the location of what used to be, 100 years ago, a marsh area," said John Gratiot, associate vice president of facilities operations and management. "Over the years sediment has flowed into the pond from the runoff."
All water from the north side of Webster Avenue, as well as water heading west down Main Street, drains into the pond via an adjacent field.
"All of that is picking up phosphorus and nitrogen and carrying that to the pond. As a result, mix in sunlight, and in the summertime you get a green-colored water that also can smell bad," Gratiot said, referring to the resulting algal blooms.
The odor caused complaints from the Occom Pond Neighborhood Association.
According to Gratiot, only natural methods will be used to clean the pond, which is owned by the College.
"Rather than mow the fields down, you wet grow a riparian buffer," he said.
The riparian buffer consists of native plants, such as weeds, shrubs and pussy willows. While it used to be mowed every year, it will now be allowed to grow for three years before being cut.
"We are encouraging the growth of woodier plants with heavier roots because they adsorb [store on the surface] chemicals," Gratiot said. "The phosphorous and nitrogen are adsorbed and used as nutrients by the plants, and we reduce the loading on the pond."
On the east bank of the pond lies the Montgomery House, a College-owned home for Montgomery fellows, who are enjoying a more scenic backyard view thanks to the cleanup efforts.
"We've gone in and planted shrubs and a riparian buffer on the south side," Gratiot said. "So instead of looking at a jungle out back there, they are looking at a nice garden."
In addition to allowing a riparian buffer to grow, FO&M has stopped using nitrogen and phosphorous fertilizers in the pond's watershed, including the Montgomery House lawn.
"It's a multi-pronged attack," Gratiot said, adding that he hoped neighbors would mimic the environmentally friendly landscaping.
Also sharing the waterfront property is the Dartmouth Outing Club house, located on the north bank of the pond. During the winter, the DOC uses the pond for ice-skating and various other winter activities. According to DOC President Anne O'Hagen '06, the house and its property do not contribute to sedimentation.
"The house is directly on the pond, but the property is mostly marshy with very little mowed lawn," O'Hagen said.
While optimistic about the effort's results, Gratiot stressed the long-term nature of the project.
"It's not something you're going to see change over night. It is an ongoing project and we're continually making changes and adjustments based on good scientific thinking," Gratiot said.