A chunk of land adding up to more than 260 acres in Pittston, including a mile-and-a-half stretch along the Eastern River, will form a new “forever-wild” Tidal Bends Wilderness Preserve, conservationists announced Tuesday.

The Northeast Wilderness Trust announced in a news release it had acquired the land, which contains a freshwater tidal zone and a mature forest. Officials said the forest appears to have not been logged for many decades. Maine Coast Heritage Trust supported the project as part of its “Marshes for Tomorrow Initiative” and the land abuts a 50-acre preserve already protected by the Kennebec Land Trust, so conservationists say the latest acquisition ensures “protection of both sides of this stretch of the Eastern River, a tributary to the Kennebec River that flows to the Maine coast.”

Officials said the Tidal Bends Wilderness Preserve features about 33 acres of freshwater tidal marsh, a state-listed imperiled natural community, and provides key habitat for several species of birds, including the rare black-crowned night heron, and state-listed rare plant species.

The 260-acre land was donated to the trust by Jim Goldman and Alyce Zellers, according to the release.

“When we read a forester’s assessment of the health and extensive variety of both animal and plant life on our Pittston land, we decided it was too valuable to be sold for timber, but should instead be preserved,” Goldman said in the release.

Jon Leibowitz, executive director of the Northeast Wilderness Trust, said about 4% of Maine land is considered “forever wild.”

“These are places where nature directs the ebb and flow of life, where natural communities are given the time and space to grow old and complex, and where resource extraction is prohibited,” Leibowitz said in the release. “The Tidal Bends Wilderness Preserve is an exceptional property where the food web relationships can be witnessed in real time and where forever-wild protections will allow nature to flourish and wildlife to find permanent refuge.”

Dan Hohl, project manager of the Maine Coast Heritage Trust, said the Pittston land preservation “ensures that the marsh will not be impacted by human development and has the opportunity to expand and migrate into new areas as sea levels rise.”