As the Island faces continued growth in its congested commercial areas, one project before the Martha’s Vineyard Commission has begun to emerge as a symbol of the breaking point.

Since 1984 when developer Sam Dunn built the Tisbury Marketplace off Beach Road, the complex has become home to a number of popular Island fixtures such as The Net Result and Saltwater Restaurant. In 1987 Mr. Dunn proposed developing additional retail space adjacent to the portion of the complex that now houses an architect office and a pizza shop. The plan was rejected by the commission for wastewater and traffic issues, but the area has since connected to the town sewer system and Mr. Dunn is now back with a new expansion plan.

On Thursday night the commission continued a public hearing that began in March on the two-story retail and apartment building plan, which is under review as a development of regional impact (DRI).

Mr. Dunn has scaled back the size of the building from 7,050 to 5,700 square feet, and added a bio-retentive roof to address stormwater runoff in the sensitive Lagoon watershed. He said he has made every possible accommodation to local concerns.

“This building does not impinge in any material way on the park area that we would make available to the public,” he said, referring to the scenic spot at the edge of the marsh that has open views across the Lagoon. “We have done everything that we can do to preserve this open area in perpetuity for the public. I just don’t know what else I can do.”

The planned development nevertheless has raised the hackles of some business owners and residents who worry about adding more traffic to the already crowded Marketplace which sits in the middle of one of the most congested road corridors on the Island.

With Saltwater Restaurant and Rocco’s Family Style Italian Restaurant recently approved for the sale of alcohol, some on the commission said they feared the area already faces a spike in traffic without new development.

A traffic study commissioned by the MVC forecasts a five per cent increase in peak hour trips to the Marketplace with Mr. Dunn’s expansion, but the developer interpreted the results positively. He cited a one-day parking study done by the commission which found that the front lot at its peak usage was 89 per cent full, while the unpaved parking lot further back never exceeded 60 per cent capacity.

But there remain plenty of critics of the plan.

In a letter to the commission Lynne Benson of the Heath Hen Quilt Shop in the Tisbury Martketplace called the development a “potential eyesore,” adding that it would be “just another building plunked on every available inch of land.”

Daniel Seidman of the Tisbury planning board, agreed. “The scope of the building has come down, there’s no doubt about that,” he said. “But when you look at what’s there now and you compare it with these plans, if you’re sitting at Saltwater looking toward the Lagoon I think it does make quite an impact.”

Mr. Dunn had another opinion.

“Some people say that this project benefits nobody except myself. I have to take the strongest exception to that,” he said. “The very people who are saying that are occupying a building that was built by the same developer.

“Presumably they are experiencing some benefit from occupying that space. People are going to live and work in this building and it will be taxed.”

But Mr. Seidman remained dubious about the greater good.

“If he builds it, sure, Sam will benefit and a couple of other people who either live upstairs or the people who occupy the businesses below will as well, but I don’t know if that’s a benefit to the public in general,” he said.

John Best, a member of the Tisbury wastewater planning committee and conservation commission, said the proposed building would be an unacceptable addition to an already overtaxed ecosystem.

“The Lagoon is at a critical point,” Mr. Best said. “We’re looking at every gallon we can possibly treat going toward nutrient reduction, not growth in retail. It was supposed to be a growth-neutral sewer system and this project was denied before there were sewers. Now sewers are in and it gets approved? That’s not growth neutrality.”

Mr. Seidman chimed in.

“It’s this issue of smart growth versus just growth,” he said. “At some point it just seems that you’re allowing willy-nilly growth without looking at what the benefit is.”

Not all businesses in the Marketplace oppose construction of the new building. In a letter to the commission Chris Pantalone and Peter Sullo of Rocco’s acknowledged Mr. Dunn’s right to develop his own property but signaled their concern about exacerbating what they called “an already chaotic parking situation.”

The hearing was closed; the written record will remain open until Sept. 2.

On Thursday night the commission also voted to hold a public hearing on a proposal to add 30 seats to the Blue Canoe Restaurant, also off Beach Road. Blue Canoe is currently approved for 50 seats. The commission also voted to hold a public hearing on a proposal to locate a new pizza and sandwich delivery shop at 45 Beach Road in what is currently unused commercial space in a renovated building.