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Designing a Path for Fish on the St. Croix River

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Kevin Bunch
February 20, 2020
grand falls dam

Fish can’t get past a dam on a river without help. Researchers are studying the best ways to help fish on the St. Croix River travel past the Woodland and Grand Falls dams, working with the owners, Woodland Pulp.

They’re studying river conditions around the dams to narrow down the most effective options for improving fish passage. The one-year study through the IJC’s St. Croix River Watershed Board will help Woodland Pulp and government agencies identify the best options for new fishways.

The majority of fish habitat in the river system is above the Woodland and Grand Falls dams, said Sean Ledwin, member of St. Croix board and director of Maine’s Sea-Run Fisheries and Habitat division under the state Department of Marine Resources. These two dams have fish ladders, but they are old and not designed for large numbers of important, native fish species. These include alewives (or river herring), American shad, sea lamprey, American eel and Atlantic salmon.

Each species has different swimming behaviors and needs for moving upstream and downstream, said Doug Bradley with Michigan-based LimnoTech, an independent researcher contracted for the project. Any new fish passageway needs to be designed for these different types of fish and the numbers that could potentially come through, as well as the unique timing for each species to make their trip.

Ledwin said potential passage options include a fish lift, which is essentially an elevator that carries the fish over the dam, and nature-like channels. These may bypass the dam entirely and give fish places to rest during their travels.

Meanwhile, New Brunswick Power is working on approvals to decommission and potentially remove the Milltown Dam, downstream of Woodland and Grand Falls. This would make it easier for fish to travel up the river to Woodland, gaining additional access to spawning grounds further upriver.

Restoring these species to their historic spawning grounds isn’t just good for the environment. Ledwin said alewives in particular are a keystone species. In addition to being caught by people for food and lobster bait, they feed sportfish, eagles, seals, and even cod and whales in the Atlantic Ocean. Historically, alewives could produce up to 1 billion juveniles in the St. Croix River system, and bringing that alewife run back would have a huge impact for commercial fisheries and indigenous communities in the region.

“There is a lot of fish habitat above this project area,” Ledwin said. “If we got good passage, we could have the largest run of river herring in North America in this system.”


A team of researchers and technical experts are working to understand the opportunities and limits of the river system and existing dams, Bradley said. They aim to identify the best options for improving fish passage considering environmental, structural and financial factors around the dams. To make those recommendations, researchers are considering issues like how the dams are operated, how water and sediments move through the river system and fish migration patterns.

The IJC’s International Watersheds Initiative is providing about US$184,000 for the project. The project is receiving additional financial and in-kind support from federal, state and tribal entities such as the US National Oceanic and Atmospheric Administration Fisheries, Fisheries and Oceans Canada, US Fish and Wildlife Service, Maine Department of Marine Resources and the Peskotomuhkati Nation and Passamaquoddy Tribe.

An initial report with recommended passage options should be ready for the St. Croix board to review sometime this summer, Ledwin added.

The final report’s findings may be useful in garnering support for public and private funding to construct improved fish passageways. As it happens, the US Department of Agriculture recently announced a program that could provide up to US$30 million for stream connectivity in Maine and the lower Bay of Fundy. Some of that funding could be used for building new fish passages at the Woodland and Grand Falls dams, Ledwin said.

Picture of Kevin Bunch
Kevin Bunch

Kevin Bunch is a writer-communications specialist at the IJC’s US Section office in Washington, D.C.

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