The long-term viability and environmental sustainability of a public-private improvement project proposed for Squibnocket Beach were subjects for debate at a public forum this week.

At a meeting hosted by the Chilmark selectmen Tuesday night, the board formally aired the plan to replace part of the roadway with an elevated causeway, remove a stone revetment, restore the barrier beach and build a new parking lot. The cost of the causeway alone is estimated at $3 million and would be paid for by the Squibnocket Farm Homeowners Association.

The plan also calls for the homeowners association to purchase 10.5 acres from the Vineyard Open Land Foundation and lease it to the town for 100 years. The land would be used for a new parking lot and an additional 1,400 feet of beachfront for town residents. Under the plan the town would pay the association $400,000 for a new long-term lease using available Community Preservation Act funds.

The plan is the result of months of negotiations and was first made public last week.

At the forum there was general agreement that some kind of long-term plan is needed for the beach, parking lot and road which have sustained heavy damage from storms in recent years. Those who attended also agreed that the revetment should be removed. But beyond that, opinions varied.

“I think you guys have done a great, proactive job of moving forward — you looked at a problem and you’re trying to solve it,” said Chris Murphy, a member of the town zoning board of appeals and conservation commission. “But it’s when you try and lock it down and make it a solid structure that you get into trouble. Every time you create something that you say is immovable, nature comes along and moves it.”

David Damroth questioned whether the plan to relocate the parking lot is worth it.

“This parking lot is extremely susceptible to weather and damage. I don’t see this parking lot being anywhere close to a 100-year solution, maybe a 20-year solution,” he said, adding:

“The town has existed for centuries and I think the solutions the town comes up with have to be long-term solutions. The impetus is coming not from the town but coming from the property owners who live out there and I don’t think the town should be forced into something rapid to solve their problem.”

Ron Mechur, a land planner and former director of the Martha’s Vineyard Commission and Vineyard Open Land Foundation who represents a group of Blacksmith Valley homeowners, also criticized the parking lot plan.

“The parking lot in this location reminds me . . . of the Jersey Shore,” he said. “If this project was proposed in Oak Bluffs [Mr. Mechur’s town of residence] everyone would say, you’ve got to be kidding.”

Mr. Mechur urged the board to consider a viewshed study and consider moving the parking lot offsite.

Peter Alpert, an attorney representing the homeowners association, called the plan the most “environmentally benign” option.

“We’re playing Russian roulette with big storms,” he said.

Martha’s Vineyard Commission coastal planner JoAnn Taylor agreed.

“If you have this elevated roadway, to me that seems to be a more benign environmental solution as well as from their perspective a more reliable access,” she said. “Then nature takes it course around and under this structure, sand moves, water moves, rock moves and nature can do with it what it wants. I think that the beach itself and the barrier beach landform has a better chance of responding to storms than it does now with the constant building and elevating every time the parking lot is washed out.”

Clarissa Allen, a member of the town beach committee, called the plan a good work in progress.

“I think what the town is moving toward is a really excellent proposal,” she said. “I think it’s so important to get rid of the revetment and any opportunity to give us more beach and a larger beach is really important to the town.”

Discussion will continue over the winter. A final proposal is expected to come before voters at the annual town meeting next April.