A numerical ground-water flow model of a hypothetical basin typical of those in the Puget Sound Lowland of western Washington simulated effects of ground-water withdrawals on rates of natural discharge to streams and springs. The model was calibrated to natural conditions and simulated effects by varying distance from well to stream, presence of confining layers, pumping rate, depth of pumped aquifer, distance from well to a bluff, well density, and recharge rate.