Utah has joined 15 other states in filing legal arguments challenging the Energy Regulatory Commission's authority to regulate state river and stream flows.

The attorney general's office signed on to a "friend of the court" brief in a California case over authority of the commission to ignore state laws and stream flow regulations in issuing federal power licenses.Drafted by Idaho's attorney general, the brief asks the U.S. 9th Circuit Court of Appeals to put a stop to FERC's interference in state stream flow and water rights decisions.

The case involves the Rock Creek hydroelectric project in El Dorado County, Calif. In an order issued on March 17, 1987, the federal commission declined to respect minimum stream flows set by California for the project, Jones said.

In its order, the commission said, "Matters that are within the commission's exclusive purview when licensing projects are not properly the subject of state regulation."

But Utah Solicitor General Dallin Jensen said Utah backs California's position that Congress didn't intend for the commission's authority to preempt state water laws.

"We have had similar problems here, but not to the extent of California and other states. But the precedent it sets is troublesome," Jensen said.

Idaho Attorney General Jim Jones said the federal commission has preempted that state's water sovereignty in a number of decisions and the California case is critical.

The brief argues that the commission is attempting through its orders to create a role never intended by Congress and to establish itself as the supreme authority over decisions related to water rights for hydro projects.

Idaho filed legal arguments in the case on Wednesday. In addition to Utah, friend of the court arguments were joined by Alaska, Arizona, Hawaii, Kansas, Montana, Nebraska, Nevada, North Dakota, Oklahoma, Oregon, South Dakota, Washington and Wyoming.