The objective of this project was to demonstrate the use of a customized geographic information system (GIS), which incorporates results of a groundwater flow model, as a decision support tool for the protection of valuable groundwater resources in the Rabat-Kenitra area of Morocco. The study area encompasses approximately 800 km(2) containing four major population centres, a major oil pipeline, numerous industries, and several major highways that are well used by large fuel and raw product transport trucks. The customized GIS is a menu-driven system designed to allow non-GIS specialists full use of the system. Two major components of this system are a real time worst-case contaminant transport model and an emergency response decision support system. The GIS-based data layers and routines developed for this project also can be used to aid in the development of resource protection, spill prevention, and emergency response plans.