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A New Hampshire dam built in 1929 to power one sawmill outlived the mill by decades; its 2024 removal reopened nearly 40 miles of brook trout habitat
A New Hampshire dam built in 1929 for one sawmill blocked a river for 95 years. Its 2024 removal reopened nearly 40 miles of brook trout habitat.
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Some old structures just refuse to go away. One stood in a river in Colebrook, New Hampshire, for 95 years. According to a January 2025 story from the U.S. Fish and Wildlife Service, the complete removal of the Washburn Mill Dam in October 2024 has restored access to nearly 40 miles of excellent brook trout habitat. It’s a big deal for a small fish.
A dam built for one sawmill
Named after its owner, Abraham Washburn, the Washburn Mill Dam was built in 1929 and powered a nearby sawmill on the Mohawk River for more than 40 years. The mill was knocked out of commission by several floods and closed in the 1960s because of weak demand for wood from small-scale operations. The building was torn down in the 1970s, leaving the dam standing for decades. The dam was 25 feet high and 100 feet long and sat about 50 feet upstream from the Diamond Pond Road bridge.
How a leftover dam hurts a river
An idle dam can still cause trouble. This one blocked fish from moving upstream and sediment from moving downstream, and the water pooled behind it warmed, reducing habitat for brook trout, which need cool water to survive. During heavy rain, the dam contributed to flooding on the road, limiting access to medical care. One neighboring landowner across the bridge had severe flooding, and another had erosion because of the sharp angle the dam made with the stream. After removal, the team restored the streambed and straightened the channel to reduce erosion.
Years of planning, then one big push
Initial planning began in 2019 when project partners visited the site. The New Hampshire Department of Environmental Services Dam Bureau and the Upper Connecticut River Mitigation and Enhancement Fund prioritized removal. The agency’s National Fish Passage Program provided $500,000, supplementing $650,000 secured by American Rivers, which led the project with the New Hampshire Fish and Game Department and the state Department of Environmental Services. Preliminary plans were developed in 2022, and the dam was completely removed in October 2024 despite weather challenges threatening the work.
What brook trout get back
Reconnecting the Connecticut River’s northern tributaries can increase genetic diversity in previously isolated populations. Colebrook’s cold, clean waters are well suited to brook trout. Jaime Masterson, an agency fish biologist involved since the beginning, says this part of the East Coast will be one of the last strongholds for the species as climate change continues. Slimy sculpin, burbot, wood turtles and other native species should benefit too. Fish numbers may not rise, since rivers are typically at capacity, but she expects “more genetically diverse fish” that can persist into the future.
Why patience matters
A 2023 study published in the North American Journal of Fisheries Management examined brook trout in the Beebe River watershed in central New Hampshire. Trout in tributaries blocked by impassable culverts were genetically homogeneous and distinct, while those in open tributaries showed a great deal of mixing. However, sampling in 2018 and 2019 revealed no significant genetic changes following a culvert removal project in 2017. The authors propose that prespawning behavior and geomorphological disturbances may have limited immediate genetic mixing, and they emphasize the need for monitoring after restoration. Culverts are not dams, so the comparison is a loose one, but it is a reminder to be patient.
In New England, many dams are 100 or more years old and poorly maintained. The National Fish Passage Program has removed or bypassed more than 3,500 barriers since 1999, opening more than 64,000 miles of upstream habitat. The U.S. Fish and Wildlife Service said in January 2025 that state brook trout monitoring could begin now that the dam was gone. Sometimes the best thing we can do for nature is remove what no longer belongs.
