ISLESBORO – A proposed 20-lot subdivision on a Maine island that has been a retreat for rich and famous people is prompting local residents into action.

Wall Street investment firm Leucadia National Corp. wants to develop a subdivision on 76 acres on the 11-mile long island in Penobscot Bay.

The proposal has prompted a debate about the future of Islesboro, where actors including John Travolta and Kirstie Alley as well as a number of Fortune 500 executives have mansions.

The hourglass-shaped island consists of two large sections connected in the middle by a narrow strip of land. Leucadia wants to build its subdivision near that strip on a peninsula just north of Bounty Cove. The company bought the parcel for $9 million in August.

Leucadia’s planned subdivision is designed to fit in with the texture of the community, said Patrick Bienvenue, who heads the firm’s real estate division.

“We are very interested in respecting the context of Islesboro,” he said.

Project supporters also say it would provide jobs and boost the local economy, which revolves around taking care of wealthy summer visitors and their vacation homes.

But a local group called Stop, Think, Plan has sprung up, with hopes of stopping the project or at least scaling it back.

Jack Knebel, a member of the steering committee, said the parcel is ecologically sensitive and that new wells drilled near the shore could allow salt water to contaminate the island’s only aquifer.

Opponents are also concerned that the project will bring more people to the island and overwhelm its ferry service. Some say the development will attract affluent outsiders who would transform Islesboro into a busier and flashier destination.

Steering committee member Paula Mirk said development on the island in the past has occurred incrementally and has involved existing families and people who have strong personal ties to the island.

“It’s tearing the place apart,” Selectman Andrew “Pete” Anderson said of the proposal.

But Jim Trimble of Trimble Realty Group in Bangor said, “The only thing shaking things up is this is a blue blood island. They don’t want to see a change.”

Leucadia National Corp. is a holding company with headquarters in New York City and $2 billion in assets. It invests in numerous industries, including telecommunications, health care, real estate, banking, manufacturing and California wineries.