 Iron Mountain Mine was a widely known sulfide-ore mine that provided valuable metals; but its reputation suffered due to extreme acid mine drainage and deposition of contaminated sediments into the Sacramento River.The mine was located in Shasta County, adjacent to Keswick Reservoir, and is known to be the largest toxic metal contributor to the Sacramento River system.The contaminated metal sediments that precipitated from the mine drainage accumulated in the Spring Creek Reservoir and Keswick Reservoir.