For the second week running last night, a plan to build an 18-hole golf course along the Edgartown Great Pond was subjected to a tough public grilling for more than three and a half hours on everything from pesticide use to membership policies.

“We’ve been sitting here listening for all this time and now it’s our turn,” declared Michael Donaroma at the outset of a Martha’s Vineyard Commission public hearing. It was the third public session before the MVC, which is reviewing the golf course plan as a development of regional impact (DRI). Mr. Donaroma is a member of the commission and chairman of the DRI hearings.

Repeating a scene from last week, some 200 Island residents jammed the lower level of the Old Whaling Church in Edgartown for the continued public hearing.

The developers and their team of experts spent the first two hours of the meeting rebutting a critique of the project presented last week by a team of experts hired by Vineyard conservation groups. The experts condemned developers’ claims that the golf course will have no impact on the Great Pond.

For the first time last night, members of the commission quizzed the developers in some detail about the project. Many of the questions centered on the use of nitrogen fertilizers, pesticides, herbicides and fungicides.

“I have a problem with a pesticide? It conjures up something that is killing something,” said commission member Leonard Jason Jr. “What would it do to your project if you only used natural pesticides?” he said.

“It would have a big impact,” replied Stuart Cohen, a turf management specialist for the developers. “What does that mean?” Mr. Jason said.

Mr. Cohen answered in part: “We would have disease problems. In terms of insects we would probably be okay. But we would have a lot of weeds that would be hard to manage. We all think about pesticides in terms of what you put in your yard. But we put a golf course through a lot more stress and we need to use things that you don’t use in your yard.”

The development is proposed for approximately 200 acres of land owned by the MacKenty and Bigelow families fronting the Great Pond. The developers of the project, called the Meeting House Golf Club, are Rosario and Barry Lattuca, a father and son team from Natick.

The project is one of two golf course proposals pending before the commission as DRIs. A separate project is planned at the site of the Old Vineyard Acres II subdivision on the north side of the West Tisbury Road. A public hearing on that proposal opened early this month and will continue next Thursday night.

There is bitter rivalry between the two golf projects, and some of the tension bubbled to the surface at various points throughout the hearing last night. A third golf course development is in the planning stages in Oak Bluffs, although no formal application has been filed yet.

At the outset last night, project manager Kelly Cardoza said the Lattucas were the first golf course developers to arrive on the scene and had their pick among the three golf course sites.

“They chose the MacKenty site because of its location on the pond,” Miss Cardoza said. The golf course plan will benefit the pond, she said, because of a plan to intercept a nitrogen-rich plume of ground water that is flowing from the Edgartown wastewater treatment plant toward the pond. “Without the golf course doing this, a publicly funded solution might be needed,” she said.

Also at the outset, landowner Jerry MacKenty issued a plea to the commission to approve the project.

And Arthur Gaines, a senior scientist with the Woods Hole Oceanographic Institution, spoke at length about the plans to capture the wastewater plume and to set up an independent scientific research center to monitor the Great Pond. Mr. Gaines is the leading expert for the golf group and has been named as the director of the new center.

Mr. Gaines called the critique by outside experts last week “red herrings, straw men, and an embarrassing display of arrogance and public exhibitionism.” He staunchly defended the science of the project, including the plan to pump nitrogen-rich ground water from an area down-gradient of the sewage treatment plant.

“This is not speculation; we have designed an irrigation well that will intercept this water. This is real and this is possible,” said Mr. Gaines. The hydrogeologist for the team later said that the plume-tapping well would be the first of its kind.

Mr. Gaines reiterated the group’s position that the irrigation plans for the golf course will actually reduce nitrogen levels in the Great Pond. He conceded a point raised last week that the nitrogen-rich ground water will not last forever, probably about 10 years, because the treatment plant has been upgraded and is no longer discharging high levels of nitrogen. But after the plume is depleted, Mr. Gaines said, the group plans to devise a way to tap directly into the discharge water at the treatment plant.

Again last night there was plenty of public comment as people stood to speak both for and against the project, well past 11:30 p.m. MVC meetings are usually gaveled to a close at 11 p.m.

Commission members also questioned the developers on an array of themes, including their science, their plans for housing summer workers and their membership selection criteria for the private golf club.

But the central theme was chemical use.

“Over a period of years, where does it all go? Does it impact the sediment in the pond?” asked commission member Tristan Israel, questioning Mr. Cohen, the turf specialist.

The golf course group will know the answer to that question, Mr. Cohen said, once a golf course is built and a planned pond monitoring program is put in place. But he said the developers plan to limit the number of pesticides, herbicides and fungicides which accumulate in the environment. “We have very little in the way of bioaccumulatives,” Mr. Cohen said.

One issue still unresolved centers on a set of local regulations in Edgartown which prohibit any use of pesticides, herbicides, fungicides or chemical fertilizer within 300 feet of the pond. The regulations, which also restrict the area of turf grass in the 300-foot zone around the pond, were developed through the District of Critical Planning Concern (DCPC) process, a special overlay planning process allowed by the MVC legislation. Five of the holes in the golf course project fall under the regulations.

“You won’t be applying pesticides within 300 feet of the pond?” Mr. Donaroma asked Mr. Cohen.

“We will have none within 200 feet,” Mr. Cohen said. “But we have the DCPC regulations,” Mr. Donaroma said. “We will be applying for a waiver,” Mr. Cohen said. “I think you should consider that as a problem,” Mr. Donaroma returned. “What is your plan if the Edgartown [conservation commission] doesn’t let you use insecticides?” asked MVC member Jim Vercruysse.

“I am hoping that won’t be a problem,” Mr. Cohen said. A short time later Mr. Donaroma returned to the subject. “This is an ‘environmental golf course’ you are proposing. Forget the pesticides in the 300-foot area. Just forget it. It’s only my opinion,” Mr. Donaroma said.

Mr. Donaroma, who owns an Island nursery and landscape business, also had a suggestion for Mr. Cohen later about weed control. “The other way to take care of weeds is manual. It’s a lot more labor-intensive and it will probably cost you guys more money. But this is an environmental golf course,” he said.