Cianbro employees guide the top of the first pole of the NECEC hydropower transmission corridor onto its base in West Forks, Maine, in this Tuesday, Feb. 9, 2021, photo. Credit: Linda Coan O'Kresik / BDN

Three of Maine’s largest conservation groups filed a motion Friday in a federal court to add the U.S. Department of Energy to their earlier lawsuit challenging federal permits that were granted to Central Maine Power for its controversial hydropower transmission project.

The Appalachian Mountain Club, the Natural Resources Council of Maine and the Sierra Club Maine said the department erred in issuing the presidential permit for the New England Clean Energy Connect project without first allowing for public comment and not thoroughly assessing the environmental impact in a new motion with the U.S. District Court in Maine. The groups said the department conducted multiple public hearings and more rigorous reviews for similar projects in Vermont and New Hampshire.

The motion would add to the original lawsuit filed in October 2020 against the U.S. Army Corps of Engineers. That lawsuit has a similar allegation that the Army Corps failed to rigorously assess the full impacts of the $1 billion transmission line on the woods, waters and communities of western Maine.

The head of the CMP affiliate running the project countered that it has undergone years of extensive review by experts at the federal, state and local levels that resulted in substantial changes to the initial design. Thorn Dickinson, CEO and president of NECEC Transmission, criticized the Natural Resources Council of Maine and the Sierra Club for attacking the project while other environmental groups were involved in the process.

“Three years later, they continue to overstate the project’s impact on Maine’s forestlands and ignore the significant reduction in regional carbon emissions,” Dickinson said. Two-thirds of the project will run along existing transmission lines, he said, and the rest will be on land already used for commercial logging.

The 145-mile corridor could bring 1,200 megawatts of hydropower from the Canadian border through western Maine to Lewiston. The presidential permit granted in January allows for construction over the border between the U.S. and Canada.

In a separate case, the U.S. Court of Appeals sided with the trio of environmental groups to grant a preliminary injunction to stop CMP from cutting trees in the 53-mile segment that comprises the final portion of the hydropower line. While much of the power line is along existing infrastructure, the final section needs to be cleared for poles, lines and other infrastructure equipment. Oral arguments for that case are scheduled for March 30.

U.S. Rep. Jared Golden, a Democrat from Maine’s 2nd District, has asked President Joe Biden to review the presidential permit granted in the closing days of the administration of former President Donald Trump. The Penobscot Nation also has asked the Army Corps of Engineers asking for a more comprehensive review of the project.

Lori Valigra, investigative reporter for the environment, holds an M.S. in journalism from Boston University. She was a Knight journalism fellow at M.I.T. and has extensive international reporting experience...