Yellowstone will have fewer snowmobiles than proposed this season.

When Yellowstone National Park opens to winter adventurers in about a month, 318 snowmobiles will be allowed in a day and another 50 allowed at nearby Grand Teton National Park. That’s 40 percent less than requested in a 2007 proposal, which a U.S. District judge threw out in September. The daily limit is still more than last winter’s average of 294 snowmobiles a day in Yellowstone. The snowmobiles also are to use the best available technology to run quieter and cleaner.

The plan is expected to be adopted by Dec. 15 and to remain in place for three years. Environmental groups have called for a ban on snowmobiles in the parks, to be replaced with a smaller number of multi-passenger snowcoaches, according to the Associated Press. Snowmobile advocates and the state of Wyoming have filed a lawsuit to increase the number of machines allowed in the two parks.