There have been many management science models proposed for optimizing various operational aspects of municipal water systems. However, our practical experience indicates that water managers view such modeling attempts with skepticism. Too much effort has been spent on developing elegant, complex models, instead of focusing on providing water managers with systems that support their total information needs. This paper presents the design and development of the Water Resource Management System (WREMS). The main distinction of the WREMS system is that the optimization model used to offer operational guidance is imbedded within an inventory data management information system, the "hook" that interests the city water managers in trusting and, ultimately, using the system. The optimization model incorporated within WREMS is a customized network simplex imple-mentation of a minimum cost network flow problem, designed to assist in making daily decisions such as which wells to produce and how to manage water levels in reservoirs. Details of the linkages between the data management and optimization components of the system are highlighted, illustrating how IS and MS/OR can be synergistically coupled.