SIOUX FALLS, S.D. (KELO) -- Seasonal gates and recreation sites that are not open through the winter on the Black Hills National Forest will be closed Monday, Dec. 16, the U.S. Forest Service said in a news release. The Forest Service said the gates are closed to provide seasonal refuge for wildlife and to protect natural resources. Some of the roads are also converted to snowmobile trials. Mega Millions jackpot climbs to $740 million The closed roads and trails are identified on the Motor Vehicle Use Map. The snowmobile trials are open from Dec. 15 to March 31. Wheeled vehicles are only allowed in a specific small segment of the Big Hill trials area that allows snow bicycles. The public should not park in front of closed gates because forest employees may be working beyond those gates. Sioux Falls police investigate deadly hit & run crash A list of campground sites that remain open during the winter can be found here. National Forest System roads are not maintained during the winter. Officials are asking people to use "extreme caution" when driving on roads that may become impassable or hazardous from the ice and snow.