Koosharem is a town in Sevier County, Utah, United States. Koosharem is also known as "Grass Valley". It generally comprises the area known as Burrville, Utah on the north, south through the valley and through the town of Koosharem and down to the south end with the town of Greenwich, Utah. The valley is made up of private lands nestled within the Fishlake National Forest. Koosharem is situated at the cross-roads for travelers going between Capitol Reef National Park and Bryce Canyon National Park and/or Zion's National Park. Koosharem is also the closest town to the famous Fish Lake. The town also serves as an important point along the many trails of the Piute ATV Trail System.
Koosharem's only store, the historic Grass Valley Mercantile, shares this secondary naming reference.
The name of the town Koosharem originates from the Native Americans indigenous to the area, the Piute Indians and their term for the valley named for the deep red clover that grows in the lush meadows of the Koosharem Valley,. The population was 276 at the 2000 census.