The U.S. Geological Survey, in cooperation with Fresno County, is developing a computer model of the unconfined aquifer system in the Fresno area. In the area, consolidated rocks are overlain by unconsolidated deposits. The unconsolidated deposits are divided into a lower fine-grained unit and an overlying coarse-grained unit. The system is assumed to be a single unconfined unit. The top of the system is the water table and the bottom is the base of the coarse-grained deposits. The northeastern boundary is the only natural lateral hydrologic boundary. The other lateral boundaries are placed so that errors along them will not affect heads in the area of interest. Initial heads for 1943, hydraulic conductivity, and bottom elevations were used in a steady-state model that generated net flux values. It is anticipated that most of the remaining effort will center on model calibration. (USGS)