State Grant Eyed As Cure For Long Pond Ills

by William F. Galvin

HARWICH — The water quality in Long Pond was generally considered better this year than in the recent past, according to members of the Long Pond Watershed Association, who met Saturday in an annual session. But the anoxic state that contributes to unhealthy conditions in the pond has not abated.

That is the conclusion of a management study conducted by ENSR International, Inc., an environmental consulting firm hired with funds from the towns of Harwich and Brewster and a state Department of Environmental Protection grant. Hope for addressing the anoxic conditions rests with a grant application seeking $350,000 from the state Department of Environmental Management. That grant, said Eduard Eichner, a water scientist with the Cape Cod Commission, will be acted upon in the next two weeks to a month.

The next step is to remove large amounts of phosphorus from the pond. It is this phosphorus that creates the anoxia, triggering algae blooms which are responsible for fish kills.

"The water was clearer this year and we’d like to know why," said association president David Kimball, a Harwich resident who lives along the pond. His observation was also supported by Brewster resident Carroll Johnson, who has been collecting fish kill data for a couple of years. He reported last year 1,500 fish perished during the summer while this year the figure was 555.

But a couple of residents among the 60 members of the association present at the community center said the waters in front of their property along the south shore of the pond had experienced severe algae blooms. They have been shoveling the vegetation off the shoreline for the past month-and-a-half. "It stinks," one resident said.

Eichner explained the basic problem is the absence of oxygen in the hypolimnion, or bottom stratification of the pond. This allows the release of phosphorus from the sediments and creates the anoxia condition. Absent that oxygen, fish will not survive, he said. The health of the pond hinges on control of the phosphorus, Eichner said.

"The bottom of the pond is not a good functioning ecosystem," the water scientist said.

"Anoxia has been a feature of deep water in Long Pond for a least half a century, but excessive internal recycling of nutrients accumulated over many years seems to be a more recent phenomenon. It may have taken many decades for the internal load to reach the threshold where it could supply sufficient phosphorus to cause the observed blooms," the ENSR management study states.

The study has identified two potential solutions. One is phosphorus inactivation through

aluminate application with a projected cost of $181,000 to $255,000. The other is installation of a hypolimnetic aeration system with an estimated cost of $300,000 to $400,000 and annual operation costs of $12,000 to $30,000. Among the potential problems with each application are the potential for aluminum toxicity and, with aeration, the need for compressors to be located along the shoreline.

The grant being sought through DEM would be for the aluminate application and to review and make recommendations on local bylaws and regulations. The permitting process would be a very public one, said Eichner. It could be done during the winter and application could come as soon as next summer, should funds be available, he added.

Eichner also identified watershed solutions that will be necessary to combat phosphorus in the long term. He cited the need for natural vegetation buffers along the pond, and management programs that minimize fertilizers. Septic system management is the primary goal, providing setbacks from the pond, upgrades of systems and inspection and maintenance. Other mitigating efforts include stormwater filtration, preserving open space and education.

The association voted to use some of its money to assist in the education process, agreeing to do a pamphlet mailing to residents around the pond defining measures that can be taken to improve conditions.

Eichner also said there are a couple more experimental technologies for keeping phosphorus out of lakes and, hopefully, if the grant is approved, they can be looked into.

Residents wanted to know what the greatest cause of phosphorus is in the pond. Eichner said it is septic systems, which are responsible for about 65 percent of the contribution. He pointed out on the Harwich side of the 740-acre pond, there are 35 systems within 100 feet of the pond and another 26 within 200 feet. On the Brewster side there are 10 within 100 feet and 21 in the 200-foot zone.

With more Harwich residents living along the pond—110 to Brewster’s 35—the association agreed as it heads toward a political phase for improving the health of the pond that it should maintain Harwich leadership. The group elected Kimball to serve as president for three years and Susan Ladue to serve again as vice president for the same period.

9/6/01