The Tisbury board of health has approved ambitious new regulations aimed at curbing the amount of nitrogen entering the Lagoon and Tashmoo watersheds.

The board voted to approve the rules at a meeting Tuesday afternoon.

“It’s a pretty big moment,” board of health member Michael Loberg said later.

Many months in the making, the new rules will require denitrifying septic systems for all new construction in the two pond watersheds. Some property transfers will also be affected, as determined by the board of health. Existing systems that fail will also trigger the regulations, although the town would need to cover at least some of the cost.

Pending review by town counsel, the regulations go into effect immediately.

Properties within an official sewer district are exempt. Those within the proposed sewer district along State Road are also exempt, but would enter the fold if the town votes to formally adopt the district. Property owners whose systems fail will not be held accountable until the town comes up with a subsidy program.

The rules have gone through a number of revisions, among other things incorporating concerns that were raised at a series of public hearings in the spring and summer. Joan Malkin, a former attorney and Chilmark resident, assisted with drafting the rules. Tisbury health agent Maura Valley also played a key role.

Board of health chairman Michael Loberg said Tuesday that he expected a subsidy plan for failed septic systems to be in place as early as April. He said he envisions something analogous to the town’s sewering policy, where the taxpayer base covers about half the cost of each connection with the user covering the rest.

“It’s the same philosophy, that denitrification is to the benefit of everyone,” he said.

The Tisbury wastewater commission and sewer review board have already voted to extend the town sewer lines to upper State Road. Mr. Loberg said he expects a final town meeting vote as early as this spring. “A lot of money has to be spent on the plant,” he said, “and in the meantime it’s possible that some of these alternative systems that we are looking at, they might be able to do what sewers do with respect to denitrification but much more cheaply. We’ll find out.”

The rules aim to protect Lagoon Pond and Lake Tashmoo from an overabundance of nitrogen by replacing conventional Title 5 septic systems, which are designed to remove bacteria but not nitrogen. Too much nitrogen and resulting algal blooms have caused a decline in the health of most saltwater ponds on the Island. Just this month biologists sounded an alarm over a sudden large algae bloom in the Tisbury Great Pond that could threaten wild oyster beds.

At their meeting Tuesday, board of health members approved three additional measures intended to complement the new regulations and further respond to public feedback gathered at the hearings.

Ms. Valley was directed to develop a plan for monitoring well water — in response to residents who questioned the findings of the Massachusetts Estuaries Project, which sets the standard for pond restoration on the Vineyard. (The MEP does not rely directly on groundwater measurements.) Mr. Loberg said the board has lost track of the existing wells, but he believes the records are retrievable.

A second monitoring effort, possibly in collaboration with the Marine Biological Laboratory in Woods Hole, will focus on groundwater in the area immediately surrounding the ponds, at a depth of about one meter.

The board of health plans to apply for a major state grant (up to $150,000) from the Massachusetts Clean Energy Council, which it would use to pilot a new septic system design developed on the Cape. Mr. Loberg said the experimental NitROE system has been shown to remove more than 95 per cent of the nitrogen in wastewater. The board hopes to install at least 10 of the systems starting in April, with a goal of obtaining approval by the state for general use. The new regulations allow for systems approved for piloting, provisional or general use.

The grant would also cover equipment and training necessary for board members to become certified in monitoring nitrogen levels. In regard to the regulations, Mr. Loberg said he believed the additional monitoring efforts might eventually warm voters to the idea of covering the testing charges, while leaving homeowners to pay for the individual systems.

Looking ahead, he said he plans to begin presenting the new regulations to town boards and others who may not have attended the public hearings this year.