LISBON — The removal of dams on Sabattus River is transforming the ecosystem and the river’s relationship to the surrounding community as old industrial pollution is cleaned up and wildlife habitat is restored, state officials say.
In 2024, crews completed restoration work at the former Mill Street dam, also known as Lower Dam and the southern most of the three projects. Remnant concrete was removed from the river channel and a natural fishway was installed. Already, the project is drawing attention as a good spot to observe herring return upstream.
“We’ve opened up important habitat for sea-run fish, but we’ve also created a more accessible and appealing space for the community,” said Casey Clark, a marine resource scientist with the Department of Marine Resources who is leading the projects.
Upstream of the Webster Street bridge, the Upper Dam was removed in 2022 after sitting unused for years. The project involved riverbank stabilization and revegetation. The work was revisited after the 2023 winter storms and was found to have withstood floodwaters, and vegetation continues to grow.
Clark said the most complex work is still ahead between the Upper and Lower dams, where three projects in development are overlapping: the removal of a third dam, cleanup of a No. 6 oil contamination site and the closure of an old landfill near the river. While the oil cleanup is expected to begin this year, dam removal and landfill remediation may take until 2026.
The project, which is led by Maine Department of Marine Resources and the Atlantic Salmon Federation, is funded from federal sources, including the National Oceanic and Atmospheric Administration and the U.S. Fish and Wildlife Service. Additional support is coming from the Maine Department of Environmental Protection and private landowner American Biltrite.
The three interventions may bring long-term financial relief to some Lisbon residents and businesses within the flood plains, Clark said. When all work is completed, officials will submit a letter of map revision to the Federal Emergency Management Agency to update area flood maps.
“We’re hopeful the updated maps will lower the official flood zone,” Clark said. “That could reduce or eliminate flood insurance requirements for more than a dozen properties.”
More than flood insurance concerns, the projects also enable habitats to mend and provide passageways for native fish species.
“It’s been proven over and over that dams can fragment fish habitat in ways that damage entire life cycles,” James Pellerin, a biologist with the Maine Department of Inland Fisheries and Wildlife, said. “Some fish species need to reach spawning grounds, nursery areas, or thermal refuge and when they can’t their populations decline.”
Pointing to the Crooked River tributary to Sebago Lake as a success story, Pellerin said the removal of dams has proven time and again that opening natural passageways for fish can improve fish populations.
“That river was blocked by mill dams for decades,” he said. “But over time, as we removed those barriers and improved passage, we saw wild landlocked salmon return. Today, about 80% of the salmon caught in Sebago are wild again.”
Pellerin said, however, that success does not come overnight. Even after breaching one of the Crooked River dams, fish initially hesitated to pass the spot. Biologists were forced to capture and transport fish upstream to encourage them to recreate spawning grounds. It’s a process that took years to pay off, he said.
The restoration work in Lisbon is part of broader efforts to reconnect Maine’s rivers and to support the recovery of declining fish species like Atlantic salmon and alewives. Since the late 1990s, dozens of dam removals have reshaped river systems across the state.
Notable examples include the removal of the Edwards Dam in Augusta in 1999, which reopened 17 miles of the Kennebec River to sea-run fish; the 2012 and 2013 removal of the Great Works and Veazie dams on the Penobscot River; the 2008 removal of the Fort Halifax Dam on the Sebasticook River; the 2018 removal of the Lombard Dam on Outlet Stream in Vassalboro; the 2022 removal of Walton’s Mill Dam on Temple Stream in Farmington; and the 2019 removal of the upper and lower Saccarappa dams on the Presumpscot River in Westbrook.
Pellerin said projects like these can take decades to see progress, but the long-term ecological payoffs are clear from those that have already seen some success.
“We’ve seen these systems rebound when given a chance,” he said. “You reconnect a river, and you’re giving those species, and those communities, a shot at recovery.”
