- UW Department of Geology and Geophysics
The current coalbed methane (CBM) play in the Powder River Basin of northeast Wyoming and southeast Montana is the most active in the United States. Large volumes of water generated during methane production present environmental concerns because the water typically contains high levels of sodium and is generally discharged at the surface, possibly resulting in the alteration of soil properties and changes to plant biomass. This study utilizes Landsat Enhanced Thematic Mapper (ETM) data and field observations for change analysis in a region of CBM production along Spotted Horse Creek in northeast Wyoming. Hypotheses tested in this study are: (1) plant biomass increases with the addition of saline and/or sodic CBM waters; and (2) CBM waters increase soil salinity, sodicity, and pH. Results indicate the application of CBM waters at the Spotted Horse Creek study site has initially increased plant biomass in areas of CBM activity. However, the CBM waters are very high in salinity and sodicity. Soil chemistry is affected such that pH, salinity, and sodicity levels have changed to the point of making the soils slightly sodic. Presently, these levels are within the tolerance limits for most of the plants in the region but may continue to increase with the continued discharge of CBM waters.