The research represents the final phase of a three-phase research project leading towards the development of a computer-oriented planning system for use in planning large, multibasin systems of reservoirs and connecting river reaches and pump-canals. Specifically, the research defines a methodology for finding an optimal size, operation, and staging of construction of a water resource system with highly variable inflows and demands that are increasing over the planning horizon and assessing the impacts of such a system. The computer programs developed during this research are designed to analyze a problem on a monthly basis using historic or stochastic hydrologic input data sequences, a specified demand build-up period, and an economic life as defined by the user.