Abandoned Mines, Mountain Sports and Climate Change:

Trouble Ahead and Trouble Behind

By

Diane McKnight

Institute of Arctic and Alpine Research, Boulder, CO

In the Rocky Mountains and Sierras, the release of acidic, metal-enriched water from the abandoned mines and associated mining wastes, referred to as acid rock drainage (ARD), is a pervasive problem that degrades water quality. ARD contamination has not abated since the mining boom ended in the 1920's because these contaminants are continuously generated from weathering reactions caused by exposure to oxygen of the pyrite in the mine workings and tailings. The streams and rivers receiving ARD are acidic (pH from 2-5), have high dissolved concentrations of toxic metals, such as Zn, Cu, and Pb, and support species-poor aquatic ecosystems. Fish are typically absent. Recently, economic development in mountain regions has been driven by the ski industry, resulting in increasing demands for water for snow-making to expand skiable terrain. The ski industry depends upon a migration of skiers to the mountains during late December, and therefore is dependent upon reliable high quality skiing at this time. The resulting demand for water for snow-making may be increasing to compensate for delays in snow pack accumulation, possibly associated with a changing regional climate. Contamination of streams by ARD constrains the use of stream water for snow-making. Thus, the ecological legacy of ARD from the previous economic boom presents both a continuing degradation of environmental quality and a limitation in sustaining the current economic vitality under a changing climatic regime. From a regulatory perspective, although ARD sites function much like point sources of pollution, one difficulty is the absence of any private party that might be held responsible for controlling the discharge of pollutants from long-abandoned mine sites. Other major difficulties in addressing ARD are geographical, technical and economic in nature.

AAPG Search and Discovery Article #90004©2002 AAPG Rocky Mountain Section, Laramie, Wyoming