The U.S. Fish and Wildlife Service last month identified thousands of miles of streams and more than 100,000 acres of lakes and reservoirs from the Pacific Ocean to the Northern Rockies as critical to the survival of the bull trout.

But when it came to a relatively small stretch of a river in a remote part of northeast Nevada with a reputation for anti-federal activism, the agency concluded the fish, a native char that is part of the salmonid family, would be just fine there without any additional regulation.

Citing a history of ''anti-government demonstrations'' and other ''substantial conflicts'' over the fish and a bordering road in a national forest, the agency reversed its proposed action from June 2004 and determined that designating critical habitat along 131 miles of the Jarbidge River would do more harm than good.

''There is a growing body of documentation that some regulatory actions by the federal government, while well-intentioned and required by law, can under certain circumstances have unintended negative consequences for the conservation of species on nonfederal lands,'' the agency said.

''There are reasonable concerns that a critical habitat designation in the Jarbidge River may negatively affect cooperative relationships between federal and local officials and discourage voluntary, cooperative conservation,'' the agency said.

The Sept. 23 decision came as a welcome relief to longtime opponents of federal protection of the fish in Nevada, including members of the so-called Shovel Brigade, who have pressed the federal government for a decade to rebuild the South Canyon Road that washed out in 1995.

''We can do a lot more cooperatively than we can in the courtroom,'' said John Carpenter, a Republican state assemblyman from Elko. ''We don't want to ruin the habitat up there for the bull trout. We don't want any species to disappear. We just want access.''

But for environmentalists - who argue rebuilding the road could help destroy the southernmost population of the bull trout in the United States by damaging the adjacent stream bed - exempting the Jarbidge River is the latest example of the administration bowing to political pressure at the expense of the environment.

''It's not about cooperation. The Fish and Wildlife Service is abdicating its responsibility to protect federal lands by appeasing the local opponents,'' said Michael Freeman, a Colorado-based lawyer who has represented The Wilderness Society and Utah-based Great Old Broads for Wilderness in a legal battle over the road.