A quasi three-dimensional model was constructed to simulate the response of the Piney Point and Cheswold aquifers underlying Kent County, Delaware to ground-water withdrawals. The model included the Magothy, Piney Point, Cheswold, and unconfined aquifers, and was calibrated using historical pumpage and water-level data. Model calibration was accomplished through the use of both steady-state and transient-state simulations.