A worker for Brookfield Renewable prepares the Lockwood Dam on the Kennebec River in Waterville for new flashboards last June. Several conservation groups in recent days have criticized Brookfield because they say its four dams from Waterville to Skowhegan impede the spring migration of juvenile Atlantic salmon. Rich Abrahamson/Morning Sentinel file

Several conservation groups are once again demanding that the owner of several dams along the Kennebec River do more to protect the endangered Atlantic salmon as its spring migration begins this month.

The Kennebec Coalition and the Conservation Law Foundation in a news release called on Brookfield Renewable Partners, the owner of four dams along the river from Waterville to Skowhegan, to take steps to protect the Atlantic salmon.

“Without real and significant changes from Brookfield we could lose the Atlantic salmon forever in the Kennebec,” the groups said in the release. “Brookfield has shown a disturbing indifference to the health of Maine’s Kennebec River by killing and harming critically endangered Atlantic salmon in clear violation of the federal Endangered Species Act. Brookfield must take immediate actions to protect Atlantic salmon at its dams during the 2022 migration periods.”

The Kennebec Coalition is composed of groups that include the Natural Resources Council of Maine, Maine Rivers and the Atlantic Salmon Federation.

Brookfield did not respond Tuesday to multiple requests for comment.

Brookfield owns the Lockwood Dam in Waterville, Hydro Kennebec Dam in Waterville and Winslow, Weston Dam in Skowhegan and Shawmut Dam in Fairfield.

The salmon migrate in the spring and fall, from April through about June 30 and roughly from Oct. 15 through Dec. 31.

The best practice would be for Brookfield to shut off turbines at each dam, the release said, and at the Weston Dam bypass channels should be opened for downstream passage of salmon. Other requests made by the conservation groups include shutting down all turbines at the Shawmut Dam and opening all gates, and shutting off the turbines at the Lockwood Dam overnight during upstream migration and at all times when there is downstream migration.

The impact of the dams on salmon migration has been a contentious issue, as last year the conservation groups filed a lawsuit against Brookfield arguing that the owner violated the federal Endangered Species Act by killing Atlantic salmon and other sea-run fish.

Less than a month later Brookfield filed a lawsuit against the state Department of Environmental Protection and the Department of Marine Resources claiming that the agencies have not conformed to a legally binding 1998 management agreement and other state laws.

And two months after those lawsuits were filed, the Federal Energy Regulatory Commission announced that it would conduct a comprehensive environmental review of the cumulative effects of the four dams on the Atlantic salmon and other fish.