The Captain Jack Mill site is located at the headwaters of upper Left Hand Creek about 1.5 miles south of Ward in Boulder County, Colorado. The site is in a narrow valley known as California Gulch. Mining for gold and silver in the region began in 1860 and ended in 1992.
The site is comprised of the Big 5 Mine (the upper mine), Captain Jack Ltd. Mill, the Black Jack Mine (the lower portal), and other mines and waste features in the immediate surrounding area. The Big 5 Mine, located about 500 feet upstream from the mill, consists of an adit (tunnel), a large waste rock pile and a settling pond. The mill works area includes several lagoons previously used for settlings tailings from the mill. The lower portal includes the Black Jack adit and the contents of a shed.
Source: US EPA Region 8 Superfund