SEATTLE — A federal judge has struck down the Bush administration’s 2004 decision to ease old-growth logging restrictions on public land in the Northwest, saying the government failed to properly consider what effect it would have on rare plants and animals.

U.S. District Judge Marsha Pechman said in her ruling late Monday that according to federal law, authorities had an obligation to show why the so-called "look before you log" restrictions — requiring forest managers to survey for rare wildlife before logging — should be eliminated.

Exactly what the ruling means for logging planned in old-growth forests remains unclear. 

"The agencies have an obligation ... to disclose and explain on what basis they deemed the standard necessary before but assume it is not now," Pechman wrote.

The judge said she would not issue any specific injunctions until further hearings are held, and the U.S. Forest Service said Tuesday it hopes to salvage the new rules by fixing the problems cited by the judge.

Environmental groups said the judge’s ruling likely has no impact on fire-salvage sales in the Biscuit fire area of southwestern Oregon or on forest-thinning operations.

Joseph Vaile, campaign director for the Klamath-Siskiyou Wildlands Center, said he believes the largest potential local impact might be on the Bureau of Land Management’s Glendale Resource Area, which Vaile said includes old-growth sales crafted in part with the provisions struck down Monday.

"We hope it winds up protecting old-growth forests with sensitive species, but we’re not clear how it will play out on the ground," said Vaile, whose group was one of the plaintiffs in the suit.

As part of a legal settlement with the timber industry, the administration eliminated the rule in spring 2004. The rule required forest managers to look for rare species before logging in 5.5 million acres of old growth and other forests in Washington, Oregon and California, and to impose certain protections, such as buffer zones, if evidence of rare wildlife was found.

Under the Bush administration’s decision, instead of surveying for rare plants and animals, the Forest Service and the BLM were to rely on information provided by the states in determining whether to allow logging, prescribed burns and trail- or campground-building.

A coalition of environmental groups sued to stop the change, saying it would double logging on federal land in the region and could have disastrous consequences for about 50 rare species, such as the Siskiyou Mountains salamander, the groundhog-like red tree vole and the great gray owl. They cheered the ruling Tuesday.

"That’s a huge decision for people who care about old-growth forests in our region and the species that depend on them," said Dominick DellaSala, a forest ecologist with the World Wildlife Fund, another plaintiff in the case.

Rex Holloway, a regional spokesman for the Forest Service, said the agency’s lawyers were reviewing the decision.

"Obviously, the judge pointed out some inadequacies in our (environmental impact statement)," Holloway said.

The change applied to 5.5 million acres of old growth and other forests designated for logging under the 1994 Northwest Forest Plan, a compromise forest-management plan that covers 24 million acres in Washington, Oregon and Northern California.

The timber industry had complained for years that "survey and manage" rules — which require study of the potential effects of logging on about 300 plant and animal species — were overly intrusive and could take years to complete.

"For us, it feels like a victory in the sense that you can’t just focus on one part of the Northwest Forest Plan and ignore another," Vaile said.

Dave Werntz, of Conservation Northwest in Bellingham, Wash., agreed.

"This is a common-sense approach that says if you go into the last remaining old-growth forests for logging purposes, you need to minimize the harm to the animals and plants that live there," Werntz said.