It rises in the foothills in northeastern Gilpin County, in southern Golden Gate Canyon State Park.

It descends through a valley eastward into Jefferson, following Drew Hill Road (County Road 57), emerging from the mountains approximately 3 miles (5 km) north of Golden, where it is impounded to form Ralston Reservoir and Arvada/Blunn Reservoir on both sides of State Highway 93.

The first documented discovery of gold in the Rocky Mountain region occurred on June 22, 1850, when Lewis Ralston, a Georgia prospector traveling with a party headed for the California gold fields, dipped his sluice pan into a small stream near its confluence with Clear Creek.

[3] He found about ¼ troy ounce (8 g) of gold, then worth about five dollars (about $550 USD today.

[6] The owners of the mine, Cotter Corp., rerouted the Ralston Creek around the mine site after uranium levels of between 40 and 50 parts per billion were discovered in the creek, greater than the 30 ppb federal drinking water standard.