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The Colorado River and its tributaries provide water to about 36 million people and irrigation water to nearly 4.5 million acres of land in the United States and Mexico. Damages within the United States as a result of dissolved solids in the Colorado River are estimated to be about $383 million per year. About 55% of the salt loading is estimated to come from rangelands. Research on the topic of dissolved-solids loading to streams from rangelands is needed for identifying management practices that could reduce salt yields to the Colorado River. Specifically, there is a need to improve the understanding of sources and transport mechanisms of dissolved solids derived from rangelands. In this study, data collected from rainfall simulation experiments in saline rangelands of central Utah were used to develop prediction equations for runoff and water quality. These newly developed equations will be incorporated in the Rangeland Hydrology and Erosion Model (RHEM) and provide a means to rank ecological sites to determine relative contributions of salt loading to the upper Colorado River. A second goal is to evaluate the RHEM model for assessing hydrology, erosion, and salt mobilization and loading responses associated with management of vegetation within the upper Colorado River Basin.