Hydrogeology of the Gillette area, Wyoming

Abstract

Gillette, Wyoming is the center of growth associated with coal development in the Eastern Powder River Coal Basin of Wyoming. Rapid growth in the area is resulting in a three-way competition for limited ground-water supplies among the city, the subdivisions just outside of the city limits, and coal strip mines. Major aquifers in the Gillette area are, in order of depth, the Wasatch, Fort Union, and Fox Hills Formations. Study of geologic and hydrologic data indicates that water in the Wasatch aquifer occurs in ancient stream channels trending to the northwest. Although mining is expected to have little affect on the municipal well field, a potential for pollutant movement from the city landfill to the well field area exists. Possible alternatives for ground-water development to meet increased demand include greater pumpage from the Wasatch and Fort Union aquifers, further exploration and development of the Fox Hills aquifer, and importation of water. Before the Gillette area can arrive at a solution to its water problems that is environmentally and economically sound, the mining companies, the City of Gillette, and the surrounding subdivisions must begin working as a group instead of in competition with one another.