The principal ground-water reservoir in part of the Sevier Desert, Utah was modeled using a three-dimensional finite-difference model. The model was calibrated by comparing computed and observed water-level measurements in 1952, simulating results of aquifer tests, and simulating ground-water withdrawals during 1952-81 and comparing computed water-level changes during 1952-82 to observed changes. The results indicate the model is capable of predicting future water-level changes. The report includes a complete listing of the model data for the 1952-82 simulation.