Chestnut-pulls an 'amazing success,' committee says

The Bare Hill Pond Watershed Management Committee reports that the phosphorus levels in the pond are lower this year, and the number of invasive plants is also dropping. At the same time, the number and variety of native plant species appear to be increasing.

Committee Chairman Bruce Leicher presented the annual report on pond conditions at the Harvard Conservation Commission's Sept. 1 meeting.

Leicher described the improvements as "pretty remarkable." He attributed the declining phosphorus levels to the flushing and refilling that occurs because of the yearly drawdown of pond waters. He explained that contaminated water is flushed out, and better quality water comes in from streams.

Conservation Commission member Pat Doherty asked where the phosphorous-polluted water goes after it drains out of the pond. Leicher said it goes downstream into a wetlands area that filters the water, with plants taking up much of the phosphorus.

The Pond Committee's written report included test results supplied by Wendy Gendron of Aquatics Restoration Consulting. The committee engaged Gendron to answer questions raised last year by the Conservation Commission. According to the report, Commission Chairman Paul Willard had asked for confirmation that the drawdowns were helping the pond and not damaging the ecosystem.

The committee report highlighted the efforts of several individuals in monitoring and promoting the health of the Bare Hill Pond ecosystem. Jeff Ritter's springtime frog counts established that peepers, pickerel frogs, and bullfrogs continue to inhabit the pond, although predation by blue herons, water snakes, and raccoons may be reducing their numbers. Leicher reported seeing 30 turtles in as many minutes in the upstream wetlands last May.

Rick Dickson's water chestnut pulls are "an amazing success story," the report says. The amount of water chestnuts Dickson gathered with the harvester plummeted from 164 loads in 2007 to just 4 loads in 2010.

"This year there were not enough plants to even use the harvester," the report said.

In response to the report, Willard said, "I'm delighted."

According to the report, reducing phosphorus is a key factor in staving off eutrophication, the process by which an oversupply of nutrients leads to excessive plant growth. Eutrophication, the report stated, can cause "oxygen depletion, fish kills, algal blooms, [and] anerobic bacteria growth," among other problems. It was high phosphorus levels that led Massachusetts in 1999 to place Bare Hill Pond on its list of endangered ponds, Leicher said. Auto exhaust is a significant source of phosphorus, he told the commission, so the chemical can come into the pond through road run-off.

Fertilizer run-off also adds phosphorus to bodies of water, but some companies are now using less of the chemical. Scott's Miracle-Gro Company, which has been reducing its phosphorus content since 2006, recently announced that its lawn fertilizer will be free of phosphorus by the end of 2012. Detergents were formerly a major source of phosphorus, but Massachusetts and 15 other states banned dishwasher detergents with phosphorus in 2010. Phosphorus in laundry detergents has been banned in the United States since 1993.

In addition to the studies done by Gendron, a team from the Environmental Protection Agency examined the pond in July. The Pond Committee has requested a copy of the EPA's findings and will provide that data when it becomes available, the report said.

The Pond Committee proposed that this year's drawdown follow a schedule similar to last year's, which was worked out in cooperation with the Harvard Rowing Association. That process would begin with a gravity drawdown in mid-September, followed by pumping from the latter half of October until Nov. 30 (barring an earlier freeze). The only change from last year, according to the report, would be increasing the drawdown level to 7 feet, from 6.5 feet, to allow winter excavations in the beach area, if the requisite permits are granted.