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Boise, Idaho • The U.S. Forest Service has issued a new policy Wednesday requiring forest managers to limit where snowmobiles can go by specifically designating what areas are open, a move that could reduce the competition between skiers and machines.

The new rules take effect Feb. 27 and apply to all national forests in the U.S.

The change follows a 2013 federal court ruling in Boise that found the Forest Service incorrectly exempted snowmobiles from a 2005 Forest Service plan restricting wheeled cross-country travel to designated routes.

An Idaho-based backcountry skier group, Winter Wildlands Alliance, filed the lawsuit that new and more powerful snowmobiles were chewing up remote and pristine powder previously reachable only by skiers.

"You can't have both uses in the same area and allow for each user to get the experience they're looking for" said Mark Menlove, the group's executive director. He said that besides carving up slopes, the machines are loud and emit exhaust.

The Forest Service estimates that nearly 4 million snowmobilers use national forest land. Advances in technology have made modern snowmobiles more powerful and lighter than previous generations. Modern tracks can propel the machines more efficiently through powder in steep terrain. With those advances, skiers and snowmobilers often compete for fresh powder in the backcountry.