The Yak Power Plant - A steam-powered generating plant and 3.5-mile tunnel that drained water and transported ore. It was built between 1895 and 1923 to drain the southern part of the district, having its outlet in California Gulch east of the town of Leadville Colorado. The tunnel became part of the California Gulch Superfund site in 1983. In October 1985, a large surge of water from the Yak tunnel reached the Arkansas River and elevated the dissolved metals content of the river for tens of miles downstream. Water flowing from the tunnel has been treated by its owner, ASARCO, since June 1991 to remove metals. Photo by Kathy Alexander.