sentences:  Most Colorado coal is used for electric power generation.Eleven coal mines operate in Colorado, including eight underground mines in Delta, Garfield, Gunnison, La Plata, Rio Blanco, and Routt counties, and three surface mines in Moffat and Montrose counties.All active coal mines are on the western slope, although the New Elk coal mine in Las Animas County is expected to reopen in 4th quarter 2010.