State Loses Water Flow Control Bid : Supreme Court: Justices rule that federal officials alone can set limit on diversion of water by hydroelectric plants.

The U.S. Supreme Court dealt a defeat Monday to state regulators and environmentalists, ruling unanimously that federal officials alone control the flow of water from rivers and streams into hydroelectric power plants.

The case, brought by the state of California, involved a small, privately owned plant along a tributary of the American River near Placerville.

The ruling means that environmentalists seeking to protect fish, wildlife or recreation threatened by hydroelectric plants will have to take their pleas to the Federal Energy Regulatory Commission in Washington. The agency is viewed by many as pro-development.

California has nearly 500 hydroelectric plants, an increasing percentage of which are private. Their generators are operated by water diverted from streams and rivers. More water means more power, and more profit for the owners. But the licenses under which they operate also put limits on how much water can be taken from a stream.

The question in this case involved who would determine that limit: the state or the federal government.

Lawyers for California argued that states traditionally have controlled the waters in their streams and rivers. They were joined in their appeal by the 49 other states. But federal officials countered that they traditionally have controlled all matters involving hydroelectric power.

In a fairly terse opinion by Justice Sandra Day O’Connor, the court said the issue had been settled in a 1946 ruling. In that case, the court said the Federal Power Act of 1935 preempted the state’s authority over water flowing into federally licensed hydro plants.

It is too late now, O’Connor said, to tamper with such a “longstanding, well-entrenched decision.”

Moreover, giving states a separate authority to limit water flowing into hydro plants would allow them to veto projects that already had been approved by federal regulators.

Ron Stork, associate conservation director for Friends of the River in Sacramento, said the ruling “means a fairly significant switch of decision-making authority to Washington.” In practice, state authorities in recent years have been able to insist that hydro plants leave an adequate flow of water in the streams and rivers, he said.

Now, the decisions will be made in Washington alone, he said.

Jack F. Fallin Jr., an attorney for Pacific Gas & Electric Co. in San Francisco, agreed that the ruling clarifies the law, but contended it will do little to change existing practices. “The state agencies will still have a strong voice in what happens. They just wanted more authority,” he said.

In 1983, the Federal Energy Regulatory Commission gave the Placerville plant a license to take water from the tributary and return it about a mile downstream. The California Department of Fish and Game said this area was an important trout breeding stream and urged that the minimum flow of water be more than twice that required by federal officials.

In some instances, hydro plants divert water from a river or reservoir and return it as far as 20 miles downstream.

In this case, when the plant’s owners and the federal commission refused to agree to keep more water in the stream, the state attorneys took an appeal to the U.S. 9th Circuit Court of Appeal in San Francisco. It ruled, however, that the federal government’s authority in this area preempts the state’s power.