A 409-acre piece of wooded property that straddles the town lines of Griswold, North Stonington and Preston, owned by a Tennessee developer for two decades, is now in the hands of the Avalonia Conservancy.

The land trust already has used conservation easements and purchases to preserve about 3,500 acres on nearly 100 properties, much of it wooded or coastal land in southeastern Connecticut, plus about 3 acres on South Dumpling Island in Long Island Sound and Sandy Point Nature Preserve, a barrier island in Little Narragansett Bay.

The property known as the Tri-Town Ridgeline Forest, surrounded by farms, housing developments and other protected woodland, is the largest parcel the Conservancy has purchased in the 50 years since it was established.

"We're really excited about it," said Dennis Main, the conservancy's president.

The developer, Billy Y. Walker of Dyersburg, Tenn., contacted the director of the Connecticut Land Conservation Council on Facebook in 2016 to tell her he had put the land, which had been bought for development in the 1980s, on the market for $1,555,000.

Members of the council contacted Avalonia and other area land trusts, Main said, and Avalonia began negotiations with Walker to buy the land.

They negotiated a price of $925,000.

"We worked hard in getting the best value we could," said Chuck Toal, the group's director of development.

Because of a Connecticut law allowing towns to tax farm, forest or open space land at a lower valuation, the previous owner likely was paying local property taxes only in the hundreds of dollars, Main said.

The conservancy is paying for the land using a $555,000 grant from the state's Open Space and Watershed Land Acquisition program, which distributes state bonding funds and money the state collects in the form of fees for the recording of land records to municipalities or conservation organizations, and a loan from the The Conservation Fund, a national nonprofit conservation organization.

The conservancy plans to use Open Space and Watershed Land Acquisition to pay for two additional smaller pieces of land nearby.

The organization is raising another about $300,000 to pay back the Conservation Fund.

The land covers an area where the town lines of Griswold, North Stonington and Preston meet, and abuts two other adjacent Avalonia properties totaling 76 acres: the Linnea Richardson Nature Preserve and Peltiers' Lost Pond Preserve.

It also abuts more than 600 acres protected by the Nature Conservancy using easements and sits near a 213-acre section of the Pachaug Forest owned by the Connecticut Department of Energy and Environmental Protection.

It features wetland and forest habitat for several species of birds and amphibians, mountains and valleys, old logging roads, 10 miles of historical stone walls, colonial farm ruins and cairns, Main said.

The property also has two chestnut oak trees that may be among the biggest in Connecticut, he said.

The conservancy soon will begin work with other local conservation groups to improve the conditions of the trails and to build new ones for walking and biking.

Volunteers with the organization already have started to identify areas of interest and geographical markers with survey tape to help with navigation as they start to develop the trails.

"It's easy with 409 acres to get turned around pretty quick," Main said.

m.shanahan@theday.com