The biogeochemistry of wetlands in the San Luis Valley, Colorado: The effects of acid drainage from natural and mine sources

The Summitville Mine, located near the old mining town of Summitville in Rio Grande County, Colorado, operated between July 1986 and December 1992 as a large-tonnage open-pit heap-leach gold mine. During its 6 years of existence the trace metal levels in drainage water from the mine site were elevated over historical (pre-1986) levels (Moran and Wentz, 1974) due to input from three sources—heap leach water, seeps that occur throughout the mine workings, and an increase in the metal load of water coming from the old Reynolds Adit. Mine-drainage waters flow into Wightman Fork, a small tributary of the Alamosa River, which in turn flows east into the San Luis Valley. The increase in the trace metal burden of the Alamosa River watershed is of concern to farmers, land owners, and Federal and State wildlife agencies.

The information presented here is largely abstracted from reports previously published (Balistrieri and others, 1995; Gough and others, 1995).