Late 1800s

Water Quality Issues Reported

What to know:

Water quality issues were likely occurring since mining began in the area. By 1938, the Left Hand Ditch Company formed a Pollution Committee and filed suit against some of the mines for damage to the creek. Acid mine drainage (AMD), commonly called Yellow Boy because if it’s orange- yellow appearance, caused vegetation and aquatic life in and near the creek to disappear. There were also accounts of horse fatalities. Yellow Boy is often highly acidic and laden with metals, including iron from the pyrite in ores. When the mine water reaches a pH of about three, iron will precipitate out of solution. The particles of iron create the yellow-orange appearance. Yellow Boy can be in indication of AMD and poor water quality that is toxic to fish, wildlife, and potentially humans.

Yellow Boy exiting Captain Jack Mine

Yellow Boy freely exiting (left photo, before remediation) and settling (right photo, after surface remediation) the Captain Jack Big Five Tunnel Adit near Ward, Boulder County, Colorado. Source: Left Hand Watershed Center.

Sampling Water Quality

Watershed Center staff member Glenn Patterson sampling water at a site with remnant iron precipitate (or Yellow Boy) in Left Hand Creek along California Gulch, downstream of Captain Jack Mine, near Ward, Boulder County, Colorado. October 2018. Source: Left Hand Watershed Center.