PORTLAND, Maine — A federal judge has ruled that a lawsuit brought against the operators of a dam on the Kennebec River in an effort to protect the endangered Atlantic salmon can move forward.

The judge ruled Thursday that the case deserves to be heard on its merits.

The lawsuit, brought by Friends of Merrymeeting Bay and Environment Maine, claims the Hydro Kennebec dam violates federal endangered species laws because it kills fish and blocks access to salmon habitat.

The defendants, Brookfield Power U.S. Asset Management LLC and an affiliate, Hydro Kennebec LLC, sought to have the case dismissed or put on hold to allow federal agencies to deal with the issue.

The companies argued the case is too complex for a federal judge to decide, and that no violation of the law is occurring.