This report describes the development of a digital computer model to simulate the hydrology of a stream basin. The model simulates both surface-water and groundwater phases and their interaction. Input to the model includes precipitation, climatic conditions, boundary and initial conditions, and basin constants. Provision has been made for modeling withdrawals from both groundwater and surface waters for consumptive use. The computer output includes streamflow hydrographs at selected points, groundwater levels, and summaries of important moisture fluxes. The model is designed to be general in nature so that it will be applicable to other basins with similar geographical and geological conditions. (Modified author abstract)