In this Oct. 11, 2008 file photo, an Atlantic salmon leaps out of the water at a Cooke Aquaculture farm pen near Eastport, Maine. Credit: Robert F. Bukaty / AP

AUGUSTA, Maine — Conservation groups filed a Thursday notice saying they plan to sue the energy giant that owns four dams along the Kennebec River between Waterville and Skowhegan, arguing it has failed to follow federal endangered species protection laws.

It is an extension of a conflict that involved Gov. Janet Mills, whose administration sided with conservationists in an effort to impose stricter fish passage requirements on Brookfield Renewable in a move that could have led to the dams’ removal. But Brookfield sued the state over the rules and the Maine Department of Marine Resources dropped the plan in April, admitting it had no authority to make the changes under state law.

Conservationists are now trying a different approach. The Conservation Law Foundation, Maine Rivers and the Natural Resources Council of Maine told Brookfield in a Wednesday letter that they believe the company’s continual operation of the four dams without gaining permission to kill a certain number of fish if they are incidentally harmed violates the Endangered Species Act.

“Brookfield’s unwillingness to do the right thing on the Kennebec is unacceptable,” said Sean Mahoney, who directs the Conservation Law Foundation’s Maine advocacy center.

The pending lawsuit is another snarl in the complicated situation around the dams. Brookfield accused Mills governor of trying to deliberately force the dams’ closure after a third party unsuccessfully tried to buy the dams. Conservationists argue the dams, even with fish passage measures in place, provide too much of a barrier to Atlantic salmon and other sea-run fish from reaching spawning grounds up the Kennebec River. 

The 60-day notice precedes any lawsuit. Federal regulators warned Brookfield last month that the continual operation of the dams could violate federal law. In response, the company temporarily shut down three of its four dams on the river last week.

A Brookfield spokesperson said the company is “disappointed” in the action occurring despite the shutdowns. The company is working on a species protection plan that it expects to complete by the end of June.