More than 260 acres in Pittston are being set aside as a wilderness preserve.
Northeast Wilderness Trust acquired the property after the landowners decided to donate it to the organization because of its ecological significance.
The land includes 33 acres of freshwater tidal marsh, mature forest and habitat for numerous species of birds along with several state-listed rare plant species.
The new Tidal Bends Wilderness Preserve abuts an existing 50-acre preserve protected by the Kennebec Land Trust.
In a statement, Jon Leibowitz of the Northeast Wilderness Trust says the forever-wild protection "will allow nature to flourish and wildlife to find permanent refuge."
Only about four percent of land in Maine is conserved as "forever wild."