Accompanying the increased use of water resources is an increased accumulation of chemical pollutants. To prevent degradation of the water resources beyond useful limits, pollution inputs from additional uses must be quite accurately predicted prior to implementation of the new use. The model described in this report was formulated to provide the required predictive capability for the Bear River Basin. In this study the model was synthesized on the hybrid computer and applied to the Cache Valley subbasin of the Bear River basin. The ability of the model to predict increased salt concentrations is demonstrated. A method for estimating and filling data gaps is also briefly discussed. (Modified author abatract)