An assessment of cumulative impacts of coal mining on the hydrology in part of the Powder River structural basin, Wyoming; a progress report
The U.S. Geological Survey and the Wyoming Department of Environmental Quality are involved in a cooperative effort to assess the probable cumulative impacts of coal mining on the hydrology in a part of the Powder River structural basin in Wyoming. The purpose of the progress report is to present initial results. Emphasis is placed upon presentation of results of analysis of surface-water resources in the Caballo Creek drainage. For the purposes of this study the assumption was made that the
... as made that the principal impacts on the ground-water system due to mining will occur in the relatively shallow aquifers. A further assumption was that the shallow aquifers can be divided into three relatively homogeneous aquifers: the Wyodak-Anderson coal, the overburden, and the underburden. A surface-water model of the Caballo Creek drainage was developed to help assess the impacts of mining activities on streamflow. The Hydrological Simulation Program-Fortran model was used in the study. The Caballo Creek drainage was divided into 10 land segments and 6 stream reaches in the modeling process. Three model simulations show little, if any, change in streamflow between pre-and post-mining conditions and very little change between pre-mining and during-mining conditions. The principal reasons for the absence of change are the small fraction of the drainage area that is mined and the rapid rate of infiltration used in the model for all three conditions.