A report issued by the state Department of Environmental Protection for the town of Chilmark provides a clearer picture of the health of Chilmark Pond, confirming that further nitrogen runoff will impair the estuary’s aquatic ecosystem.

The saltwater pond is generally healthy with no serious habitat damage, but nitrogen levels in the pond are at their limit, according to the report from the Massachusetts Estuaries Project.

As a result, the estuary “is beyond its ability to assimilate nitrogen without further impairment,” the report said.

Ongoing for the past several years, the MEP program aims to identify the factors contributing to nutrient pollution and habitat destruction in 89 estuaries on the Cape and Islands. MEP reports have already been done on the Vineyard for a large number of ponds, including Edgartown Great Pond, Sengekontacket, Lagoon Pond, Farm Pond and Squibnocket Pond.

The major work of the project involves setting a nitrogen-loading threshold for the ponds. The program does not offer specific recommendations for mitigating the problems at each site, but offers a starting point for communities to begin developing plans of their own.

The Chilmark Pond report saw initial discussion among the town selectmen last week.

The pond has no evidence of eel grass, an important aquatic plant in coastal ecosystems, so the study focused on the health of the pond’s benthic animal habitat. The MEP recommended that the nitrogen level in the estuary be reduced from about .74 to .5 milligrams per liter to support aquatic animal life.

The pond is part of a complex embayment made up of a large central basin and several smaller basins. The main basin is maintained by periodic mechanical breaching through a single inlet, as scheduled by the town.

According to the report, the estuary “is particularly vulnerable to the effects of nutrient enrichment from the watershed, due to its very limited tidal exchange.” More frequent or prolonged openings to the sea can lower nitrogen loads in the same way as “relieving nitrogen related habitat impairments,” the report said.

The MEP said restoring the benthic habitat and achieving the desired nitrogen level could be accomplished by reducing nitrogen loading from the watershed and by breaching the pond three times per year, including a period in the spring when the breach would remain open for eight days.

The selectmen noted the report’s absence of more specific recommendations, and hoped to consult with experts at a later date.

Warren Doty pointed out that a recent project to dredge a sandbar at Edgartown Great Pond has led to more successful flushing of that estuary. “Maybe that is part of the Chilmark Pond solution,” he said. “How that would be done is a question — and at what cost.”

He added that a mitigation plan for Chilmark might include adding shellfish to the estuary, since shellfish, especially oysters, remove nitrogen from the water.

A pilot project to grow oysters in the pond is already underway, begun last year with the help of the Martha’s Vineyard Shellfish Group.

Town executive secretary Tim Carroll said the state’s favored solution to nitrogen pollution is to install sewers, since a large amount of nitrogen runoff comes from septic tanks. But Chilmark has no central sewer system and doesn’t want one, Mr. Carroll said.

“We don’t want sewering, we just want the baseline of this,” he said, referring to the report. He explained later that the option of opening Chilmark Pond to fishing would require extensive research and that the estuaries program was a good place to start. He said the town’s goal was to preserve its aquaculture and shellfish resources into the future.

The selectmen agreed to address the issue at a future meeting with the authors of the MEP report, who work at the University of Massachusetts at Dartmouth.