Author: Steven Lange
Date: January 2018
Metals loading adversely impacts the Animas River in the area around Silverton, San Juan County, Colorado. (Church, et al., 2007). The metals of concern include iron, aluminum, cadmium, copper, lead, zinc, arsenic, and nickel. (U.S. Geological Survey, 2007 at 7). The metals loading in the Animas River is due to acid rock drainage. (Yager and Bove, 2007). Acid rock drainage refers to acidic water that is created when sulfide minerals are exposed to air and water to produce sulphuric acid. The acidic water can dissolve area minerals and then deposit metals in rivers like the Animas. (von Guerard, et al., 2007). Metals loading in the Animas River has limited aquatic life, including the trout fishery downstream from Silverton. (Butler, et al., 2001).
Sunnyside Gold Corporation (SGC) was formed and acquired the Sunnyside Mine in 1985 and mined it from 1986 until 1991 under modern environmental regulations and using modern mining techniques. Since 1985, SGC has engaged in more than 30 years of reclamation and remediation in the Silverton Caldera. This Paper analyzes the geologic setting and historic mining that have caused the metals loading in the Animas River as well as the effect of SGC's mining and extensive reclamation activities. It is the conclusion of this Paper that is incontrovertible that the actions of SGC have substantially reduced acid rock drainage and metals loading in the Animas from what would have otherwise been the case.
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