The Belle Fourche River is the largest tributary of the Cheyenne. Rapid, Sulphur, Plum, Cherry, and Owl Creeks are important other tributaries of the Belle Fourche-Cheyenne. Snowmelt from the Black Hills provides the major source of river water. Because of the proximity to the Black Hills and its mining industry, the Cheyenne historically picked up large quantities of zinc, arsenic, and cyanide. Those pollutants are no longer a major threat due to water quality regulations. The Cheyenne River is still higher in dissolved mineral content than any other South Dakota major river.