(MONEY Magazine) – Teton Valley, Idaho is the sort of place where you wish you lived. And that is its biggest problem. Snug against the western slope of the Grand Tetons, this quiet valley with plentiful wildlife and a 120-year history of agriculture is under siege. Family farms and the occasional ranch, like that of Jim and Treva Dewey, longtime ranchers with 480 acres and 145 cows, still dominate the landscape. But "the pressure to build is so strong," says Michael Whitfield, a conservation biologist and founding president of the Teton Regional Land Trust, "and we've already lost so much."

As a child, the 56-year-old Whitfield, a fourth-generation Teton Valley resident, fished and hunted on the Deweys' property. Like much of the valley, it's home to a variety of wildlife, including the regal Sandhill crane. "We're a community of outdoor enthusiasts, environmentalists, ranchers, hunters and farmers," says Whitfield, "and you need open space for those things." What has brought the community to a crossroads is the combination of land that is cheap compared with nearby towns like Jackson Hole, Wyo. (where "the millionaires are getting pushed out by the billionaires," says Treva) and the struggle of local farmers and ranchers to get by. "We're not making what we used to with the cattle," says Treva, "but that doesn't mean we want to stop doing it."

Thanks to the Teton Regional Land Trust, they won't have to. Launched by Whitfield in 1990, the trust is a local land conservation organization. Today the Deweys have 178 acres in a conservation easement, joining 57 other families who donated some or all of the development rights to a total of 20,000 acres. The Deweys still own the land and ranch on it, but they cannot subdivide. Whitfield's quiet determination was key to the donation: "I'm not sure if it was persistence or nagging, but he kept calling until we came around," jokes Treva. Giving the development rights to the trust also solved an estate issue. Because their land has appreciated so much, their son James, 41, wouldn't be able to pay the tax on the estate; the easement reduced the land's value by 60%.

The land trust isn't all business; it also runs programs for the local elementary school students and the community. Whitfield favors the storytelling get-togethers. "It's hard for a community to maintain a sense of place, to remember where we live and what our history is," he says. "And conservation can persist only if future generations value those assets." --A.W.