What Geologically classified as a "massive sulfide ore deposit", uses an earthfill dam on Spring Creek primarily to collect severe acid mine drainage stemming?
Spring Creek Dam:  Completed in 1963, the dam, maintained by the U.S. Bureau of Reclamation, serves primarily to collect severe acid mine drainage stemming from the Iron Mountain Mine. Iron Mountain Mine:  Geologically classified as a "massive sulfide ore deposit", the site was mined for iron, silver, gold, copper, zinc and pyrite intermittently from the 1860s until 1963.
Iron Mountain Mine