Several DSSs have been designed to help policy makers develop pollution control plans for river basins and estuaries. Davis et al. [1991] presented a prototype of a DSS designed to allow policy analysts to examine the effects of different land-use and land-management policies on water quality. The prototype was evaluated by the South Australian Engineering and Water Supply Department, with a second version to be designed. Cubillo and Rodriguez [1991] described a DSS for managing the operation of wastewater treatment plants along the Canal de Isabel in Madrid. Using a water quality simulation model, a data base, and an interactive user interface, the DSS would help decision makers decide what level of treatment was necessary to meet the water quality goals under the given flow conditions. Orlob et al. [1991] discussed the use of mathematical models and computer graphics in the assessment of eutrophication of the Venice Lagoon. The hydrodynamic and water quality impacts of alternative control strategies were presented in animated graphic form for user evaluation. Meijerink et al. [1993] applied a DSS to the management of the Komering River basin in Indonesia. Aerospace and terrain data were coupled with a simulation model and a decision rule base in a GIS to aid decision makers in the evaluation of the interrelationships between economic productivity and environmental degradation. They concluded that the integration of GIS in a DSS could be a powerful tool when reinforced by remotely sensed data, a relational data base, and field surveys.