Citing the need to protect Sengekontacket Pond and better understand the effects of build-out on water quality, the Edgartown board of health voted last month to impose a moratorium on septic system and well permits in the Ocean Heights and Arbutus Park section of town.

The moratorium, which amounts to a ban on new construction, is in effect for 60 days and expires Nov. 19. It may be extended by the board.

Ocean Heights and Arbutus Park are an area of densely built, substandard lots located off the Edgartown-Vineyard Haven road in the outskirts of town and stretching down to the Boulevard which fronts the pond. The area is not serviced by the town sewer system and instead features individual septic systems and wells. Some homes in Ocean Heights have begun to tie into the town water system, which means they would not be subject to the requirements of Title V, the state sanitary code that limits the number of bedrooms in a home based on the lot size.

Edgartown health agent Matthew Poole said this week that the purpose of the moratorium is to gather data on build-out scenarios in Ocean Heights and Arbutus Park, as well as existing groundwater quality and water quality of Sengekontacket Pond.

The information will help the board of health determine whether existing rules and regulations for the area need to be updated or changed, Mr. Poole said.

Traditionally, homes in Ocean Heights and Arbutus Park have been served by on-site wells. But in recent years, more homeowners have paid the town water department to tie into the town water system. By doing so, these homes are no longer subject to state health rules pertaining to the number of bedrooms, and homeowners are free to build larger homes with more bedrooms.

The larger homes are still served by septic systems, which means potentially more discharge and more harmful nitrates entering the groundwater.

The board of health first considered a moratorium after Mr. Poole presented information about the large number of unbuildable lots in Ocean Heights that would suddenly be buildable if they were to connect to town water.

In light of these developments, Mr. Poole said, health officials want to know the potential impact on Sengekontacket Pond.

"I think the board realized that the type of development in that area is changing. It's still a handful of homes [that have tied into town water], but it's getting to be a pretty big handful. Ten years ago this really wasn't an issue, but that has changed fairly quickly," Mr. Poole said.

Although larger homes with additional bedrooms could potentially alter the character of Ocean Heights, Mr. Poole said the board of health is strictly concerned with the effect on the quality of drinking water and the water quality of Sengekontacket Pond.

The moratorium will give the board time to gather data about the existing number of dwellings, the number of vacant lots, the size of the lots, the number of existing bedrooms and the number of potential bedrooms based on build-out scenarios, Mr. Poole said.

The board will also determine the number of dwellings served by on-site wells and town water, and gather water quality data from existing on-site wells and from Sengekontacket Pond.

The board will use the information to determine whether the town health regulations need to be changed for the area, Mr. Poole said.

He emphasized there is no guarantee the regulations will change.

"We just want to have a better understanding of how future development will affect the quality of drinking water and [Sengekontacket] pond," Mr. Poole said.

Board of health member Kathleen N. Case agreed.

"We just want to know what is what. We aren't trying to stop development, we just want to know what the right thing to do is. All you have to do is look at that area and see it's changing pretty quickly," Mrs. Case said.

William M. Wilcox, water resource planner for the Martha's Vineyard Commission, said he has concerns about increased development of small lots in the area of Sengekontacket Pond and its effect on water quality.

He said he supports the board of health putting the brakes on new permits for septic systems and wells near the pond to allow time to gather information.

"Any time there is a housing density greater than one house per acre, there are questions about water quality - not to mention that this area is already very close to a nitrogen sensitive waterway like Sengekontacket," Mr. Wilcox said.

Mr. Wilcox said there are already strong indications that the pond is suffering from the effects of too much nitrogen, including a loss of eel grass.

Mr. Poole said the moratorium and upcoming review of the town rules and regulations might also better prepare the town for the findings of the Massachusetts Estuaries Project, a collaborative effort by two state agencies, the Executive Office of Environmental Affairs (through the Department of Environmental Protection) and the University of Massachusetts School of Marine Science and Technology.

The project will provide water quality, nutrient loading, and hydrodynamic information for coastal waterways across the state - including Sengekontacket Pond and Edgartown Great Pond.

Once the report is complete, state environmental officials are expected to suggest land use changes to bring about improvement.

Mr. Poole said there is no direct link between the moratorium and the estuaries project, but he said that taking steps now - such as gathering data and considering changes to the town regulations - will ensure that officials will not be caught unawares when the final report is ready.

"We can almost anticipate what issues the estuaries project will want us to address. So it's better to be proactive now than be reactive down the road," Mr. Poole said.