The U. S. Forest Service intends to carry out a disputed plan that specifies where and when snowmobiles may travel in the Flathead National Forest. The winter motorized recreation plan six years in the making was the subject of six unsuccessful appeals. The plan allows snowmobiles on 91 percent of the forest trails and terrain historically open to them, the Forest Service said. That amounts to about 787,000 acres. The general snowmobile season will be Dec. 1-March 31. Within the 787,000 acres, 52,400 will be open for an extended season. The season’s end will vary from place to place, with May 31 the latest closure. The appeals included snowmobile advocates’ concerns about restrictions. Also in appeals were snowmobile critics’ claims that extending seasons violates terms of previous forest planning, terms intended to protecting grizzly bears. The Swan View Coalition, an environmental group, said a court challenge of the snowmobile plan is likely. Montanans for Multiple Use spokesman Fred Hodgeboom criticized what he called an effort to manage the forest as though it is a wilderness area or park. Hodgeboom said Montanans for Multiple Use does not plan a lawsuit over the snowmobile issue. The group already has filed a suit charging the Flathead National Forest is creating an overarching forest plan in a piecemeal and illegal manner, through amendments such as the one spelling out the new snowmobile rules.