With rising concern over the health of Sengekontacket Pond, an application to build near the shore of the pond may fail where others, grander in scale and more intrusive in scope, have succeeded.

The latest in a series of town conservation commission hearings on a plan by John Lacroix to build a modest home on his waterfront property on The Boulevard drew vocal opposition from neighbors and the Friends of Sengekontacket, a nonprofit group dedicated to protecting the pond.

Mr. Lacroix and engineer Reid Silva offered staunch defense of what they argued was a modest proposal packed with environmental controls. Mr. Lacroix wants to build a three-bedroom house with a deck on three and a half acres near the corner of 3rd street on The Boulevard.

The property lies within 200 feet of saltwater, 100 feet of fresh water and 100 feet of the storm line. All three factors are triggers for conservation commission review. Additionally a large section of the property is wetland.

As a result most of the land is unbuildable.

With rising sea levels, the situation will only become more dire with time. In a letter to the commission William Wilcox, water quality planner for the Martha’s Vineyard Commission, said a water level rise of one foot or more is quite possible over the lifetime of a septic leaching system on Mr. Lacroix’s property.

Hard facts about the pollution of Sengekontacket Pond will be hard to come by before the completion of the Massachusetts Estuaries Project report for the pond, but results will be ready by this time next year, Mr. Wilcox said.

But there are signs that pollution in the pond has been exacerbated by housing development, and Mr. Wilcox predicts nitrogen reduction efforts will be needed in the watershed.

Indicators of nitrogen overload include large rafts of wrack algae which smothers organisms as they decay.

In 1990, 90 per cent of the pond’s eelgrass disappeared. Today the only eelgrass on the pond is in Major’s Cove. Eelgrass is generally not able to thrive in water with more than 0.5 parts of nitrogen per million; Mr. Wilcox believes the algae is responsible for the failure of eelgrass restoration projects on the pond.

The estimated nitrogen load into the pond is around 21,000 kilograms per year with 55 per cent coming from septic systems.

However, there are currently no limits on how close a property owner can build to the Sengekontacket salt marshes. The Edgartown wetlands protection act triggers a review for building within 200 feet of the waterline, and the conservation commission makes a judgment based on its predicted effect on the environment.

This is different from the Edgartown Great Pond which is part of a district of critical planning concern and where building within 100 feet of wetlands is prohibited.

At the meeting Wednesday conservation agent Jane Varkonda recommended that the commission reject Mr. Lacroix’s application based on the original plans.

But Mr. Silva offered several amendments to the plan. A revised building sketch does not show a planned garage and lawn, taking the building back to some 50 feet from the wetland, though there will be a portion of land cleared in front. A high-tech nitrogen removing septic system has been approved by the board of health.

Mr. Lacroix’s property is divided into two lots but was considered a single parcel for the purpose of the commission meeting; he owns the land with his sister Nancy. At the meeting he explained that the property is part of a retirement plan and has always been taxed as buildable land.

“I’ve been paying taxes for over 50 years on what we thought was a buildable lot,” he said, “I asked the town for a rebate on the taxes at one point and was told no. This is a very modest proposal . . . an expandable chicken coop.”

The plan has prompted vocal opposition from the Friends of Sengekontacket.

Member Robin Bray read part of the latest in a series of opposition letters from the group into the record.

“Some say it will set a dangerous precedent to deny this application,” she said. “We believe the opposite is true. To grant a permit on this site where the potential impacts to sensitive wetlands resources are so clear, will make it all the more difficult to deny future applications for construction projects on the pond’s shores . . . The time to say ‘no more’ is now. The pond will soon reach a point of no return.”

Neighbor Charles Carlson also opposed the plan.

“What happened to that pond happened inch by inch,” he said afterwards, “I’ll never clam there again in my lifetime.”

Janet Riley, a retired marine biologist, read a letter urging the committee to reject the application. She said that a once pristine pond in which a scalloper looking through a peep sight could be easily distracted by an abundance of wildlife had become overloaded and cloudy with filamentous algae.

But Mr. Silva argued that blame for the troubles of the pond was being unfairly heaped on a single application.

Everyone is concerned with the pond but it’s not fair to look at this very modest house and say, that’s the culprit, to pin it all on that property owner,” he said.

Mr. Lacroix chimed in.

“I don’t hear anyone else in the area saying I’m going to stop flushing the toilet on my property, and I’m going to move away,” he said. “For me it’s a question of justice. I’ve paid taxes on the property; it’s very modest. It’s more modest than other houses along The Boulevard.”

Mr. Silva argued that because the property falls under the jurisdiction of the conservation commission, there would be greater control. “A guy just outside the buffer zone could have a 20,000 square foot lawn which he fertilizes twice a year,” he said. “This will pale in comparison.”

Commission member Edith Potter was unswayed.

“I feel sorry for you but things have changed. I feel we have to say no . . . It’s just too close to the wetland,” she said.

But member Pamela Dolby argued for the permit.

“I don’t care if this does or doesn’t get built,” said Ms. Dolby, who is also the town administrator.

“I’ll just say the town has approved very large homes. People did things they shouldn’t have and maybe the town was lax. But in this situation we asked for a number of changes in the application, and we’re controlling the size of the house square footage. Yeah, there are issues with the town pond, everybody knows that, but taking mistakes over the years and pinning it down on a house you can control in every way . . .”

Chairman Peter Vincent asked Ms. Dolby how she squared her view with the fact that Ms. Varkonda recommended the application be rejected. Ms. Varkonda interrupted to clarify that she would need to reconsider the application in light of the revised building plan.

Later Ms. Varkonda said she is not yet convinced the revisions significantly change the simple fact the plan calls for a dwelling very close to the shore.

“They were significant changes but I don’t know whether it mitigates the adverse effects. I mean, it’s not a modest house,” she said.

She said she has learned from experience that building in the buffer zone is problematic.

“Trees get cleared for paths to the shore, lawns are extended . . . It requires constant monitoring and enforcement,” she said, adding: “We’re learning more about the pond . . . it’s not without its problems.”

The hearing was continued to July 15. A site visit is scheduled for the same day.