The system, designed to be a watershed management tool, can analyze actual situations and simulate scenarios that may occur in the basin. It is made of the following parts, working integrated and interatively: (1) GIS and a database, which holds current information on all relevant aspects of water resources management, as well as projections for expected area development and water use evolution; (2) physical (hydrologic and water quality) simulation models, which allow the evaluation of water quantity and quality; and (3) an economic simulation model, which addresses the investments needed for water resources conservation and improvement and incomes from water use taxes.