Bulldozers and bird-watchers aren’t natural partners. But development is making conservation a possibility for one sprawling saltwater farm in Bar Harbor.

The Maine Coast Heritage Trust is working in partnership with the Mount Desert Island Housing Authority to provide shelter for local workers and for area wildlife.

When a priceless piece of the island came on the market two years ago, neither group could afford to buy the 176-acre property in Salisbury Cove.

Together, however, the organizations are bringing to life a hybrid project offering conservation land and at least 20 “affordable” and efficient houses.

Though the groups come from “completely different philosophies,” the relationship works because they both have the community’s interest at heart, said Terry Kelley, director of the housing authority.

“Would we like to see the whole thing conserved? Of course we would, but we’ve got people who work here and live here, and need to find a home,” said David MacDonald, director of land protection at the land trust’s Somesville office.

The property, complete with a historic yellow farmhouse on Route 3, had been priced at $2.5 million – out of reach for almost any nonprofit group. There was no shortage of profit-seeking bidders who imagined a lucrative housing development on the grassy marsh, which was not encumbered with any conservation easements or other limits on construction.

But owner Fred Pooler, who until a recent move to Colorado ran the Route 66 restaurant on Cottage Street in Bar Harbor, wanted to see his farm in local hands and consented to sell the property for $2 million to the local groups.

Pooler had considered developing the property himself, but with his retirement pending, he didn’t want to commit to years of permitting and construction, he said. He approached Kelley, saying: “I see in the paper that you need housing. Why don’t you buy my acreage?”

Both the housing authority and the land trust had expressed interest in the property, but neither organization could meet the bids being submitted by commercial developers. The two had been working together on a community planning effort called MDI Tomorrow, and it became just a matter of picking up the phone to complete the collaboration that Pooler encouraged, MacDonald said.

When the deal closed last September, the Maine Coast Heritage Trust took charge of 101 acres for a $750,000 commitment and now is raising the funds from private donors. Known as the Northeast Creek Preserve, the land is open to hikers and closed to development.

The marsh is beautiful, but its real value lies in the tiny fish and shellfish that start their lives in Northeast Creek, an estuary – a blend of fresh and salt water – that runs through the property. Seabirds feed on the young fish, and the marsh itself provides important habitat for deer and other wildlife that is being squeezed out as island towns grow. The creek is the only pristine estuary left on the island, according to U.S. Geological Survey scientists, who studied the watershed in 2001.

“Northeast Creek is the driver for us,” MacDonald said. “This estuary is the most important wetlands system on Mount Desert Island.”

The conservation land around the creek eventually could be turned over to Acadia National Park, as it is within the boundary for future park acquisition set by 1968 legislation.

“We have a very keen interest,” Acadia Superintendent Sheridan Steele said.

The majority of Northeast Creek is on parkland, and protecting more of the watershed is a major park goal. Tight park service budgets, however, make the purchase impossible now.

“We want to move toward [the purchase], but how long it would take is anybody’s guess,” Steele said.

The housing authority took possession of the remaining 75 acres, most of which is composed of forested hills far from the creek. Maine Coast Heritage Trust provided the authority with a short-term $250,000 loan, which will be repaid from the profits of selling the Pooler home and about 10 acres on Route 3. The house is already on the market at an asking price of $675,000.

A few additional acres may be kept in public ownership for a community organic farm – another project of MDI Tomorrow – provided organizers can find someone to work the land, MacDonald said.

The affordable development part of the project, on about 65 acres, will include 20 to 30 small homes designed for local workers – the teachers, police officers and shopkeepers who keep Mount Desert Island humming but who cannot afford property in this vacation community. Residents could start moving in as early as next fall.

The homes will be designed to be water- and energy-efficient. They’ll rely on nontoxic and, when possible, recycled materials. Some might even be independent of the electric grid. A small windmill may be built to run water pumps. Most crucially, the septic systems will be designed to preserve Northeast Creek, Kelley said.

“It’s not going to be [a matter of] coming home at night to a traditional home and turning all the lights on,” he said.

The “green” construction will save homeowners money.

“Just by orienting the house in the right direction will save 25 percent of your heating bill,” Kelley said.

And with clever financing and hard work, the housing authority can make the homes themselves affordable, Kelley said. Keeping them so in a place with a booming real estate market will be the bigger challenge. The key is separating the value of the land from the value of the house. With this subsidy, the homes will cost far less than a similar-sized property elsewhere on the island. Homeowners are free to sell their property at a profit, but they can’t become real estate speculators. For example, if they buy the original house at 80 percent of its market value, they can sell it for no more than 80 percent of its increased value, allowing the next homeowner to benefit from the authority’s efforts, Kelley explained.

Only after 30 years of residence may homeowners acquire the land beneath their house (lot sizes have yet to be determined). The remainder of the land will be held in common, Kelley said.

“The only way it works is for us to take the cost of land out of the equation,” he said.

The concept is known as a community land trust, a broad term that describes the unique collaborations that are becoming increasingly common nationwide. The Institute of Community Economics in Springfield, Mass., has 160 members in its Community Land Trust Network and estimates that the national tally is somewhat higher. One of the largest projects, in Burlington, Vt., has grown to 370 homes and 270 apartments.

The Burlington group recently conducted a survey of its members and noted that residents of the affordable housing are very successful in making the transition to the open market.

They build equity, improve their credit and learn to be homeowners. Then they pass the opportunity on to someone else, said Michelle Lancto of the network’s Springfield, Mass., office.

“Conservation is only a fraction of what’s intended by a community land trust,” she said.

Though created as a means of building a sense of community in the 1960s, the idea is now popular in places such as Florida and California where home values have been rising in recent years. Several small projects already have been completed along Maine’s highly developed coastline.

Unlike a purely conservation or housing project, community land trusts are successful because they’re flexible. They can serve myriad constituencies and as a result tap multiple sources of funding.

“They don’t rule anything out,” Lancto said. “Everyone’s interests are balanced.”

Some scholars have pointed out that these cooperative projects can atone for some of the gentrification of neighborhoods that often is blamed on conservation easements, as more and more land becomes off-limits to development.

“Mount Desert Island isn’t alone in this. There are a lot of places that are under the same kind of pressure,” Kelley said.

The housing authority already has more than enough local residents interested in the housing, but since regulations prohibit him from pairing interested buyers with homes before the paperwork is complete – reviews by the Bar Harbor Planning Board and the Maine Department of Environmental Protection await – they were not available for interviews.

“Interest is not an issue,” Kelley said. “Trying to put this together at a price they can afford, now that’s another story.”