A federal judge has ruled that a snowmobile trail on the edge of the Boundary Waters Canoe Area Wilderness does not violate federal law.

The 50-page decision by District Judge John Tunheim in Minneapolis comes after a nearly decade-long legal battle over the two-mile-long trail near McFarland Lake in northeastern Cook County.

Tunheim dismissed claims that the trail violated both the federal Wilderness Act and the National Environmental Policy Act.

The trail is not in the designated wilderness, but snowmobiles on it would be close enough - about 400 feet in some cases - to be heard in the BWCAW, opponents to the trail noted. Environmental groups said that would violate the intention of the Wilderness Act.

Snowmobile groups disagreed, saying there is no formal buffer zone around wilderness areas.

Tunheim eventually agreed with the snowmobile groups and the U.S. Forest Service, which had backed the trail that connects McFarland to South Fowl Lake.

In his opinion, Tunheim said the Forest Service acted properly in developing a process to replace an illegal trail with a designated trail. And he said any noise impact would be minimal.

Tunheim made it clear that he was not establishing any new wilderness policy and that he only was backing Forest Service process.

While the route selected "will increase the volume and duration of sound heard at Royal Lake and Royal River, these increases are not significant enough to constitute a Wilderness Act violation,'' Tunheim wrote. "Ultimately, the most any wilderness visitor will hear due to Alternative 2 is sound equivalent to moderate rainfall. More importantly, that impact will only occur in a small portion of the affected wilderness. Indeed, in an area that has been surrounded by snowmobile and other motorized traffic since the time it was designated as wilderness, where there are few winter visitors and the expectation of solitude is slim."

The debate started in 2002 when Forest Service rangers began issuing tickets to snowmobilers riding on what had been a commonly used but technically illegal route between the lakes. Eventually, Superior National Forest officials designated a new, two-mile route after an environmental review and public comment period.

After the route was proposed, environmental groups filed suit in 2006. In 2007, Tunheim ruled the noise issues needed further analysis by the Forest Service. After the analysis the Forest Service still backed the trail, and environmental groups sued again, leading to Friday's decision.

The Izaak Walton League of America, Wilderness Watch, Sierra Club North Star Chapter and Northeastern Minnesotans for Wilderness had filed the suits against the trail. They have 60 days to decide whether to appeal the decision to the 8th Circuit Court of Appeals.

The U.S. Forest Service, Cook County, Conservationists with Common Sense and the Arrowhead Coalition for Multiple Use filed to support the snowmobile trail.