BAR HARBOR – Mount Desert Island could become a playground for vacationers and summer residents only unless serious changes are made to zoning and planning laws in all four island towns, a crowd of 200 year-round residents concluded during a daylong conference Saturday.

The turnout for the 8 a.m. conference gratified the residents’ group MDI Tomorrow, organizer of the event, but also underscored the urgency many year-round residents feel about the mounting problems on the island.

“The size of the crowd here today indicates that a lot of people believe there is a lot to be fixed” on MDI, said Bar Harbor Town Councilor Jeff Dobbs.

The conference was held at the waterfront resort Atlantic Oakes and attracted a broad array of people, including municipal officials, teachers, architects, youth advocates, business owners, school board members, accountants and developers. It is the largest meeting of MDI residents yet in the yearlong effort by MDI Tomorrow to craft a 10-year plan for the island.

Although tourism traffic and congestion are starkly visible problems, the most pressing challenge on MDI is the cost of housing and the growing number of subdivisions that tax the limited infrastructure of the four island towns. The result is a growing summer population, workers who can’t afford to live on the island, and an aging population being taxed out of their homes.

The conference concluded that without significant changes in zoning and land use laws to encourage affordable housing on MDI, the year-round island life that Mainers love would disappear – perhaps within as few as 20 years.

“We need a miracle,” Lelania Avila of Bar Harbor told the crowd at the conclusion of the conference, “and the beauty is we are that miracle.”

As daunting as the housing problem is on MDI, the 200 residents grappled with other serious subjects such as the low wages of many workers in the MDI-Ellsworth region; the 20 percent of people in Hancock County who don’t have health insurance; a drug and alcohol problem among MDI teens that the communities are reluctant to talk about; and a business community that mostly closes for the winter.

But Mark Lapping of Cumberland, the conference’s keynote speaker, planning expert and author, told the crowd to remember why they choose to live on MDI year round: the small-town life, the ocean and Acadia National Park.

“This is the real world of democracy, when people get together [and] grab hold of their future,” Lapping said. “But don’t focus only on your problems. Focus on the assets and how to make them work for the community in the future.”

Lapping also encouraged new cooperation among the island towns, paraphrasing Benjamin Franklin in cautioning: “It’s critical to hang together, or you will surely hang alone.”

After reviewing all the challenges, the conference broke up into about 20 discussion groups and then melded back together at the end of the day to offer possible solutions. Among the most popular:

. Create an islandwide planning group and insist that the four towns cooperate more when changing or making zoning laws.

In three of the four island towns – Southwest Harbor is the exception – development is growing at twice the state average. A study by College of the Atlantic shows another 15,000 dwellings could be built on MDI under present zoning laws.

. Create incentives for property owners to rent their homes and apartments year round, rather than evicting tenants for the lucrative summer rental season, and consider disincentives for short-term rentals.

. Rewrite zoning laws to allow for “in-filling” of the villages on the island, particularly encouraging more density by reducing the amount of land required for new housing. Under existing zoning laws, the average MDI worker cannot afford either an existing home on the island or land on which to build one, participants agreed.

. Allow apartments downtown and permit homeowners to build so-called “in-law” apartments that would open up new housing options and help homeowners pay their property taxes.

Other, more radical ideas caused the crowd to laugh nervously, including converting the Trenton Bridge to a toll road, banning car traffic on MDI except for residents and service vehicles, and consider a building moratorium.

The next MDI Tomorrow public forum is scheduled from 6 to 9 p.m. Thursday, Nov. 21, at MDI Regional High School. All ranking municipal and school leaders on the island have been invited to meet with residents to continue the discussion about a long-range plan for MDI.

The event begins with a benefit lasagna supper followed by the open forum.