The first of the long-awaited studies of the health of Vineyard ponds by the Massachusetts Estuaries Project is set to be released within weeks and will recommend significant changes to the management of the Edgartown Great Pond.
The comprehensive scientific analysis of the health of the Edgartown pond has found that it is still moderately affected by nitrogen pollution, although there has been a great improvement in water quality over recent years since the upgrading of the Edgartown wastewater treatment plant.
The report will call for the pond to be opened to the ocean more often so it can flush more effectively, and will also recommend steps be taken to further reduce the amount of nitrates flowing into the pond by upgrading septic or extending systems in the pond watershed.
Brian Howes, technical director of the estuaries project and professor at the school for marine science and technology at the University of Massachusetts in Dartmouth, said yesterday that the final technical report on the pond is complete and has been forwarded to the state Department of Environmental Protection (DEP) for its approval prior to public release, probably within the next two or three weeks.
Reports on three other ponds - Sengekontacket, Lagoon and the Tisbury Great Pond - are expected to follow at regular intervals over the next 11 months, Mr. Howes said.
Sengekontacket will likely be next, in part because of community interest in moving it up the order of priorities, resulting from problems with bacterial contamination. State fisheries managers announced last week that Sengekontacket will be closed to shellfishing from June through September on a permanent basis, marking the first permanent pond closure in the history of the Vineyard.
Mr. Howes said it will likely not be the last. "The Vineyard's going to get a slew of these over the next couple of years," he said. "The towns now have to start making hard decisions."
He said the major management change recommended in his report calls for the Edgartown Great Pond to be opened to the sea more often and for longer, particularly during the summer months.
"Now mainly it is most often opened in the spring and fall," Mr. Howes said, "not so much in the summer.
"We need to focus more on that critical summer period, because it's when it's hot that the nitrogen impacts are greatest."
Excessive nitrogen levels present a threat to the health of ponds because they encourage the growth of algae and other marine weeds which choke desirable plant species, particularly eel grass, with detrimental effects up the food chain.
Addressing the pond's problems also will require more work to cut off the sources of nitrogen entering the pond, either through upgrading individual septic systems within the pond watershed or through the installation of cluster treatment systems or expansion of the town sewers, Mr. Howes said.
But he also said the health of the pond already is improving as a result of steps taken by town authorities, and he expressed optimism that things could be made much better without too much extra cost.
"The fact is it will continue to improve over coming years because of improvements already made. We're still seeing the historical effects of the [former wastewater treatment] plant that hasn't been open since 1996," he said.
Because groundwater moves slowly, maybe only a foot a day toward the pond, a plume of heavily contaminated water is still affecting the pond and could continue to do so for another decade or more.
"The pond is not as healthy as might be. It is classified as moderately impaired by nutrients. But it is particularly sensitive because it is only periodically open. If it was open all the time to the tides, at the loading that it has it would be in great shape," Mr. Howes said.
"We're pretty darned certain that some of the recent improvements - since about 2000 - in Edgartown Great Pond are because management of the opening has attempted at least to become more regular and structured.
"There is a schedule and they are trying to meet it. That has led to some short-term improvement even while we're waiting for some of the watershed improvements to impinge upon the pond."
Once the report is cleared by the DEP, Mr. Howes said, a round of meetings will be held with various stakeholders and eventually the general public over the course of a couple of months.
"We want to get out there and start doing the workshops with the regulatory agencies, the conservation commission, the shellfish departments and so on. We want it as good as can be. We don't want any local knowledge omissions," he said.
After that, the results will return to DEP for the development of a maximum daily load report, codifying management targets.
A sophisticated $12.5 million study that uses state of the art computer modeling, the estuaries project now has finished work on 32 of 89 ponds on the Cape and Islands. Sampling work began on the Vineyard for the Edgartown Great Pond report nearly five years ago. Sengekontacket sampling was done three years ago.
Mr. Howes said the long delay in completing the Vineyard reports is partly because the modeling which had proven to work on fully tidal ponds elsewhere in the region proved inadequate for the task of analyzing ponds which are open sporadically.
Bill Wilcox, the water resource planner for the Martha's Vineyard Commission, who has assisted the estuaries project with data, agreed that the sporadic opening and closing of the ponds made the work more complex.
To further inform the hard decisions to come, Mr. Wilcox said, he and the Great Pond Foundation, a private group, plan a new round of groundwater sampling in the pond watershed in the coming weeks, to determine the progress of the plume of contaminated water from the old treatment plant.
When last checked about two years ago, well sites between the old plant and the pond still showed high levels of ammonia.
"That old effluent has still got to travel through the groundwater and reach the pond and empty out the nitrogen before the improvement really appears," Mr. Wilcox said.
He said the travel time from the treatment plant to Meshacket Cove is roughly 10 years.
"Ammonia does not move exactly with the groundwater. It tends to stick with the sediment, so it could be it will take longer for this ammonia to get stripped out," he also said.
But Mr. Howes said even though water quality may continue to improve in coming years as the plume diminishes, that does not eliminate the need for more frequent pond openings.
"We project forward to when there is no plume. Even when the plume's gone, you'll need to do something about opening. This is not a short-term thing. It's a long-term solution," he said.