Because decision makers are typically required to consider a multitude of social, legal, economic, and ecological factors, DSSs have great potential for improving the planning and management of conjunctive use (ground and surface water) systems. However, only a few applications have demonstrated this potential in the past four years. Andreu et al. [1991] presented a computer-assisted support system for water resources management including conjunctive use. The system integrated a number of simulation and optimization models with interactive graphic input and automated display capabilities. The system was implemented on a microcomputer and applied to a case study of the Segura River basin in southeastern Spain. The authors concluded that the DSS provided an adequate framework for the discussion of water allocation conflicts in the basin. Stansbury et al. [1991] linked a conjunctive use simulation model, an impact analysis module, and a multiobjective decision module in a DSS for water transfer planning. The purpose of the DSS was to help decision makers analyze the social, economic, and environmental impacts of water transfers. A case study was conducted in which ten different water transfer alternatives in south-central Nebraska were examined, and the DSS proved valuable in forcing the consideration of a wide range of impacts, allowing decision makers to incorporate more technical information into the decision making process, and providing output which could be readily interpreted. Frysinger et al. [1993] described a DSS for the design of a monitoring well network which would meet the U.S. Resource Conservation and Recovery Act groundwater monitoring regulations. Integrated in the DSS were a highly interactive graphical user interface, various simulation models, and a GIS. A probabilistic approach was developed to minimize subjectivity in the regulations.