Geologic And Vegetation Mapping Using Aviris Data At Summitville, Colorado And In The Adjacent San Juan Mountains And San Luis Valley

From 1985 through 1992, the Summitville open-pit mine produced gold from low-grade ore using cyanide<br>heap-leach techniques, a method to extract gold whereby the ore pile is sprayed with water containing cyanide,<br>which dissolves the minute gold grains. Environmental problems at Summitville include significant increases in<br>acidic and metal-rich drainage from the site, leakage of cyanide-bearing solutions from the heap-leach pad into<br>an underdrain system and several surface leaks of cyanide-bearing solutions into the Wightman Fork of the<br>Alamosa River. The mine’s operator had ceased active mining and begun environmental remediation, including<br>treatment of the heap-leach pile and installation of a water-treatment facility when it declared bankruptcy in<br>December 1992 and abandoned the mine site. The EPA immediately took over the Summitville site under EPA<br>Superfund Emergency Response authority. Summitville was added to the EPA National Priorities List in late<br>May 1994.<br>Summitville has focused public attention on the environmental effects of modern mineral-resource<br>development. Soon after the mine was abandoned, Federal, State, and local agencies, along with Alamosa River<br>water users and private companies, began extensive studies at the mine site and surrounding areas. These studies<br>included analysis of water, soil, livestock and vegetation. The role of the U.S. Geological Survey (USGS) was<br>to provide geologic, hydrologic and agricultural information about the mine and surrounding area and to<br>describe and evaluate the environmental condition of the Summitville mine and the downstream effects of the<br>mine on the San Luis Valley. The environmental condition of the Summitville area is a result of the geologic<br>evolution of this area that culminated in the formation of precious-metal mineral deposits and a result of the<br>mining activity. Understanding the geologic and hydrologic history of this area is a critical piece to<br>understanding the environmental puzzle at Summitville.