Milltown Dam Removal Brings Adjustments to Fish Passage Work on St. Croix River

As of this summer, the Milltown Dam is no longer impeding fish passage along the St. Croix River.

The dam’s owner, New Brunswick Power, has been in the process of decommissioning and removing it since the summer of 2023. Milltown Dam was the first barrier that sea-run fish species, such as alewives and shad, had to navigate to move up the river to spawn. While there is still some work to be done at the dam site, that portion of the river was passable for alewives in time for their 2024 spawning season, the company says.

“NB Power’s Milltown Decommissioning Project is progressing with work on both sides of the international border,” said Phil Landry, executive director of the project managing office and engineering for New Brunswick Power. 

“This includes the Canadian shoreline restoration work and on the US side, removal of the remaining structures in the St. Croix River. These activities will happen over the summer and fall with decommissioning finishing up this year.” 

The company also is restoring a waterfront baseball field for the community.

The dam’s removal has brought a welcome wrinkle in tracking the number of alewives entering the river to spawn, something that various entities have been doing since the 1980. In the dam’s absence, these groups have been developing other methods and focusing on other structures to study fish movements in the river.

The IJC’s International St. Croix River Watershed Board supported a fish tagging effort to assess fish passage at the Woodland, Grand Falls and Vanceboro dams, farther north on the river. 

In this study, alewives were caught and embedded with a radio tag that pings receivers along the river, allowing researchers determine where fish are moving in relation to a dam. This project helps researchers better understand the extent to which the dams are impeding fish passage up the St. Croix River. At this time, the tagging effort has only included alewives. This is a joint effort with the Passamaquoddy Nation at Indian Township, the Peskotomuhkati Nation at Skutik, Woodland Pulp and New Brunswick Power.

Additional underwater cameras are installed at Woodland Dam and Vanceboro Dam, past Grand Falls and at the outlet of Spednic Lake, to aid in the fish count.

A portion of the Milltown Dam still standing on the US side of the river, as seen in June. Credit: IJC

As of 2024, fish counts have started to take place at the Woodland Dam.

“With the Woodland Dam now the first dam along the St. Croix River following the Milltown Dam decommissioning, the SCIWC reviewed daily underwater footage of the river-herring migration from the Woodland dam’s fish ladder from May-July,” said Neal Berry, executive director of the St. Croix International Waterway Commission (SCIWC). “610,452 river-herring were counted during 2024.”

The SCIWC cautioned that these counts cannot be directly compared against those done previously at the Milltown Dam site as not all fish proceed through the Woodland fish passage system.

A 2021 St. Croix board feasibility study proposed that fish passageways at the dam be wholly upgraded, as existing structures are inadequate to allow most fish past the dam. Since then, the Maine Department of Marine Resources and the Passamaquoddy Tribe have worked to secure funding to upgrade the fish passage systems at Woodland. 

Thanks to the US Bipartisan Infrastructure Law and Inflation Reduction Act, the Maine Department of Marine Resources and Congressionally directed funds, this project now has full funding, said Sean Ledwin, director of Sea Run Fisheries with the Maine Department of Marine Resources. It will be going out for bid in late 2024/early 2025, with work to begin next year. The preferred approaches proposed in the board’s report will be used for this effort. The report estimated that the work should cost around US$20 million.

“This funding will allow for completion of this exciting project to restore millions of sea-run fish to historic habitats and provide an ecological and economic boost to the region,” Ledwin said. Under the proposal, Woodland will see two new passageways for upstream movement, new downstream filter screens and bypasses for fish to safely head back out to sea, a new bridge and broader dam improvements.

Beyond Woodland Dam lies the Grand Falls Dam, which according to the 2021 feasibility study also has an outdated, largely ineffective fish passage structure. Replacing that with a new fishway is expected to cost around US$35 million, Ledwin said during a St. Croix board meeting in June. Ledwin added his agency is pursuing designs and funds for that as well in partnership with the tribe and The Nature Conservancy. 

If new fish passage systems are in place on both the Woodland and Grand Falls dams, that would open up 99 percent of the alewife habitat along the St. Croix River, allowing the species the opportunity to eventually return to the historic runs the river saw before the dams were put in place. Alewife are valuable as food for humans and wildlife, as well as bait for lobster fishing.