Environmental advocates have made good on a pledge to go after dam owners to protect the endangered Atlantic salmon.

Friends of Merrymeeting Bay and Environment Maine have filed lawsuits in U.S. District Court in Portland claiming dam owners are violating the federal Endangered Species Act and Clean Water Act by not providing the salmon with safe passage.

The lawsuits, filed Monday against each dam owner, name four dams on the Kennebec River and three on the Androscoggin River.

An attorney representing the groups said it’s the first lawsuit of its kind nationally, going after private companies, not the government, to protect the fish.

“We’re at a situation where there’s little time left; these dams are pushing an iconic Maine fish to the brink of extinction,” said Emily Figdor, director of Environment Maine. “It’s too bad we have to sue the dam owners to act, but they’re breaking the law and we need to stop killing the salmon.”

Of the four dams named on the Kennebec, NextEra Energy owns dams in Skowhegan, Fairfield and Waterville, while Brookfield Renewable Power Inc. and an affiliate own a dam in Winslow.

NextEra spokesman Steve Stengel said Tuesday that company officials “have not seen the lawsuit therefore have no comment at this time.”

Julie Smith-Galvin, spokeswoman for Brookfield Renewable Power, said, “We are reviewing the filing and have no comment at this time.”

The lawsuits were expected. In July, the Bowdoinham-based Friends of Merrymeeting Bay and Douglas Watts, president of Friends of Kennebec Salmon, announced that they planned to sue unless the dam owners acted to protect Atlantic salmon in the Kennebec River.

With the addition of Environment Maine to the case, dams on the Androscoggin were added to the list. The group is part of a federation of advocacy organizations across the country called Environment America.

The salmon, declared an endangered species in 2009 by the federal government, are being sliced up and killed as they pass through turbine blades at the dams, say the environmental advocates, who suggest “basic” protective measures to prevent migrating fish from swimming into the spinning blades.

The groups said in a statement that the dam owners have declined “simple protection measures — such as installing effective devices to divert salmon from turbines — that have been adopted elsewhere.”

Also in the lawsuits are claims that the dam owners are violating “water quality certifications” issued by the state under the Clean Water Act by allowing downstream-migrating adult salmon and adult shad to pass through the turbines of the dams without doing studies to prove such passages are safe.

The Kennebec River was home to 100,000 Atlantic salmon before dams were installed in the early 19th century, Watts said, but now the fish are in danger of extinction.

In 2010, five adult salmon returned to the Kennebec and 10 returned to the Androscoggin, according to the environmental groups.

The lawsuits say that the salmon in the Kennebec and Androscoggin rivers are protected under the Endangered Species Act.

By hampering their passage, the dams are denying them access to “significant amounts of spawning and rearing habitat” and altering their natural habitat “to such a degree that the essential behavior patterns of the fish are significantly impaired,” the groups claim.