Abstract: An intensive study was made of a 24-square mile (62-square kilometer) area surrounding the South Bend wastewater treatment plant to document the effects of dewatering about 40 feet (12 meter) of the 130-feet (40-meter) thick aquifer during construction at the plant, define the hydrologic system in order to allow development of a predictive model and select and evaluate one possible water-supply development plan as a model demonstration. Model-simulated water levels agree very well with those observed, both before and during dewatering. Model results indicate that the hydrologic system can sustain withdrawal of 28 million gallons per day (106,300 cubic meter per day) indefinitely with little effect on ground-water levels. The quantity that would be diverted from the St. Joseph River is less than 10 percent of the estimated minimum daily flow.