The technologies and methods to develop and deploy decision support systems to aid in water resources planning and management have matured considerably over the past four years. However, certain aspects of this field are changing rapidly even now. For example, the possibility of quickly accessing and processing large, spatially distributed databases over high-speed, readily accessible networks offers a tremendous improvement in the way that these systems are developed and the effectiveness with which they are used. While this aspect of DSS has not been reviewed here, it is anticipated that it will have a major impact on the field over the coming four years. The growing acceptance of graphical, user friendly operating systems and software has opened the door for more decision makers to take an active role in the use of these systems in water resources. This trend should continue and will likely bring more focus on the formulation of support systems which are responsive to the needs of the decision makers rather than the modelers and developers.
In spite of rapidly advancing computer technology and the proliferation of software for decision support, relatively few DSSs have been developed, implemented, and evaluated in the field of water resources. We believe this is due to a general lack of communication between analysts and decision makers (or their technical support staff). Possibly, analysts are just too impatient or inflexible to pay attention to the organizational context in which decisions are made. Meanwhile, decision makers and technical staffs may be reluctant to seek support and reveal their reasoning for fear of being replaced by computers. In this respect, ``expert'' systems could be a poorly chosen name, and potentially overzealous DSS developers must be careful not to imply decision automation instead of decision support. Another reason for decision makers' reluctance, though, might be simply that the words of Lord Mansfield are still remembered: ``[In making a decision]...never give your reasons; for your judgment will probably be right, but your reasons will certainly be wrong.''
Acknowledgments. The comments and encouragement of D. P. Loucks and R. F. Reitsma were greatly appreciated in the preparation of this paper. The senior author's research in this field has been supported by a National Science Foundation Graduate Fellowship.