ERROL, N.H. — A 16,000-acre national wildlife refuge will be a key part of a plan to protect a pristine lake on the Maine-New Hampshire border, federal wildlife officials announced Wednesday.

The refuge would be adjacent to Lake Umbagog, home to New Hampshire’s largest population of nesting loons and osprey and to the first bald eagles to nest in the state in four decades.

The protection plan is being developed by a coalition of federal and state wildlife agencies, conservation groups and the two major landowners, James River and Boise Cascade, the U.S. Fish and Wildlife Service announced.

Regional Director Ronald Lambertson said details will be made public in September, when a series of informational meetings will be scheduled.

The plan “will ensure permanent protection for this unique and valuable ecosystem,” Lambertson said.

The service said the proposed refuge will include large areas of wetlands along the lower Magalloway and upper Androscoggin rivers in New Hampshire and the Dead Cambridge River in Upton, Maine. Land for the refuge would be bought or protected with conservation easements, legal agreements restricting use of the land.

Brad Wyman, general manager of the woodlands division of James River, a paper company with a large mill in Berlin, and his counterpart with Boise Cascade, a paper and wood products giant, both hailed the plan.

“We want to show that timber management and private ownership of land can play an important role in preserving our natural heritage for future generations,” Wyman said.

Bob Withrow, woodlands manager for Boise Cascade, said the team approach to protecting Umbagog “offers the certainty of continued protection for the valuable watershed for future years.”

The wildlife service statement did not identify participating conservation groups

Environmentalists have for several years cited Umbagog as a rare example of an almost pristine lake and warned that without action, its shores might soon be developed.

The wildlife service said moose, deer and bear are abundant around the lake, and the wetlands make it “one of New Hampshire’s top waterfowl habitats.”

Lambertson said both states have identified protecting Umbagog as a priority under the North American Plan, an international agreement intended to prevent a further decline in duck populations.