Output from an ensemble of seven global climate models for contemporary and future scenario climates was used to drive the Soil and Water Assessment Tool (SWAT) to examine components of the hydrologic budget for the Upper Mississippi River Basin (UMRB). Results showed only modest increases in precipitation (+6%) and streamflow (+3%) but substantial reduction in snowfall (-37%) for the UMRB for the end of the 21st century. The low-resolution of global models contribute to the biases in some but not all hydrologic components, most notably evapotranspiration, potential evapotranspiration, and baseflow. Ensemble results indicate an increase in baseflow (+12%) and decrease of runoff (-20%) for the future scenario. Such changes would likely decrease sediment loading of streams, but influences on the fate of fugitive nitrates is indeterminate from this preliminary study. Evaluation of water quality in a future scenario climate carried out with one model (GFDL) suggested that major reductions in snowmelt and surface runoff in a future climate will lead to reductions in all contaminants simulated (sediment, nitrogen, and phosphorus).