A federal appeals court has agreed with conservationists that the U.S. Forest Service must protect a wilderness study area adjoining the northern boundary of Yellowstone National Park from damage and disruption caused by snowmobiles and dirt bikes.

Hyalite Creek and Lake. (Jody Duran)

The ruling by the U.S. Court of Appeals for the Ninth Circuit addresses the Forest Service’s travel management plan for the 155,000-acre Hyalite-Porcupine-Buffalo Horn Wilderness Study Area in southwest Montana’s Gallatin National Forest. The area encompasses the crest of the Gallatin Mountain Range and constitutes the largest block of roadless public land adjoining Yellowstone National Park that has not yet received protection as a designated wilderness.

The area contains important habitat for grizzly bears, wolverines, and lynx, but the Forest Service authorized escalating levels of snowmobile and motorcycle use in the area. In response, conservation groups—including the Greater Yellowstone Coalition, Montana Wilderness Association, and The Wilderness Society—filed a lawsuit to enforce legal protections for the area under the 1977 Montana Wilderness Study Act.

Today’s ruling overturned the Forest Service’s decision. The court ruled that the agency had “ignored the obvious impact of increased volume of motorized and mechanized use” on the area’s wilderness character.

“There are a lot of places to go snowmobiling or ride a dirt bike, but there is only one Yellowstone ecosystem,” said Earthjustice attorney Tim Preso, who represented the conservationists in the litigation. “This court decision reaffirms that this stretch of wild land adjoining the park boundary is a special place that should not become a motorized playground.”