(WEST YELLOWSTONE, MT) — The National Parks Service has released its winter use plan for Yellowstone. The measure would call for 318 snowmobiles, 78 snow coaches, and 50 snowmobile groups each day. Officials say they’d like to see cleaner and quieter winter vehicles in the park. The park service is taking public comment through May to determine if any adjustments should be made. If approved, the measure would go into effect during the 2014-2015 season.