MISSOULA, Mont.— In response to a lawsuit by conservation groups, a federal court today struck down a U.S. Forest Service plan to log more than 16,500 acres of pine forests just outside Yellowstone National Park, in the Custer Gallatin National Forest.

The decision found that the agency violated the National Environmental Policy Act, National Forest Management Act and Endangered Species Act. It halts the South Plateau project and requires the Forest Service and Fish and Wildlife Service to redo key analyses to protect threatened grizzly bears and Canada lynx.

“This ruling makes it clear that agencies can’t just rubberstamp massive logging projects and promise to sort out the details later,” said Kristine Akland, Northern Rockies director and senior attorney at the Center for Biological Diversity. “The court saw right through the Forest Service’s vague plans and determined that moving targets aren’t good enough, especially when threatened animals and treasured public lands are at stake. This is a great ruling for grizzlies, Canadian lynxes and the entire Yellowstone ecosystem.”

The court ruled that the agencies’ use of “condition-based management” unlawfully delayed critical decisions — including where to build 56.8 miles of temporary roads — that are necessary to assess the project’s threats to grizzly bear secure habitat and compliance with Forest Plan standards. The judge also found that the agencies relied on flawed and unsupported assumptions in their Endangered Species Act review, including an unscientific definition of secure habitat and inadequate analysis of how road placement affects grizzly bear survival.

“This decision protects one of the most important wildlife corridors in the Greater Yellowstone Ecosystems,” said Mike Garrity, executive director of the Alliance for the Wild Rockies. “The agencies must now go back and do the rigorous, science-based analysis the law requires.”

“This project proposed new clearcuts and more roads in an especially vulnerable and problematic area for Yellowstone grizzly bears and did so without specifying the location of the roads and without applying the best science on habitat needs of bears,” said Matthew Bishop, senior attorney at the Western Environmental Law Center. “By failing to inform the public about where over 58 miles of new roads would be located and arbitrarily defining secure habitat for grizzly bears as small as 10-acre patch sizes, the agencies played too fast and loose with the law and the science. The court got it right. This is an important win for grizzly bears and grizzly bear recovery in the Greater Yellowstone Ecosystem.”

The South Plateau Project would have authorized clearcutting, thinning, prescribed burning and major road construction across 16,462 acres over 15 years in core habitat for grizzly bears, lynx and other wildlife. Today’s ruling requires the agencies to identify actual road and treatment locations, use best available science, and demonstrate compliance with wildlife protections before the project can move forward.

“This is a big win for grizzly bears. The court affirmed what we all know — Yellowstone bears need large areas of intact habitat to recover,” said Adam Rissien, rewilding manager with WildEarth Guardians. “The federal agencies got it wrong when asserting that grizzlies only need 10-acre patches free from roads in an otherwise fragmented landscape. They need much more.”