MINNEAPOLIS — A proposed snowmobile route bordering the Boundary Waters Canoe Area will not violate the Wilderness Act, a federal judge ruled Friday in a decision that disappointed environmental groups that have claimed the route would disrupt the area’s pristine peace and quiet.

U.S. District Judge John Tunheim’s ruling comes after a nine-year battle between snowmobile enthusiasts and environmental groups. Tunheim acknowledged his ruling was a “close one,” but said the increased sound from snowmobiles would not be significant enough to violate federal law.

The route to be built by the U.S. Forest Service would connect McFarland Lake to South Fowl Lake, where ice fishing is better. Tunheim said the noise would be no louder than a “moderate rainfall” and would affect only a small portion of the wilderness.

The proposed route would come within about 400 feet of the BWCA.

“We are deeply disappointed in the judge’s ruling and we believe this new snowmobile trail will definitely impact the wilderness,” said Kevin Proescholdt, conservation director for the national organization Wilderness Watch. “Our fear is this will be another cut in the death of a thousand cuts to the Boundary Waters.”

Supporters of the route say it is long overdue.

“It just shows the common sense of the judge’s decision that there are motor noises already there that you hear in the Boundary Waters,” said Nancy McReady, president of Conservationists with Common Sense. “lt would be nice to have this trail started as soon as they can.”

Nancy Larson, district ranger for the Gunflint Ranger District of the Superior National Forest, said the community was split. Now that the judge made his decision, her staff can begin reviewing the project and develop a plan to implement it.

“In light of the time that has passed, I recognize there is going to be a lot of interest in constructing it as soon as possible,” she said.

The groups opposing the snowmobile route, including the Sierra Club Northstar Chapter, Northeastern Minnesotans for Wilderness, Wilderness Watch and the Izaak Walton League, have 30 days to file notice of appeal. Their attorney, Kristen Marttila, said if her clients appeal, they will ask the courts to delay construction while a decision is pending.

Snowmobiles are almost entirely banned in the Boundary Waters, but there are several exceptions.

The fight over the new snowmobile route dates to the winter of 2002-2003 when forest rangers discovered people were using an illegal trail through the BWCA to get from McFarland Lake to South Fowl Lake. A fence was built to block use of the illegal trail.

Tunheim wrote that the Royal Lake and Royal River area that would see the most impact from the route is virtually unvisited during the winter. “Therefore, the practical effect on wilderness visitors during the entire winter is minimal at most,” he wrote.