The U.S. Army Corps of Engineers, Texas Water Development Board, Texas Commission on Environmental Quality, Texas Parks and Wildlife Department, river authorities, regional planning groups, consulting firms, and university researchers model the development, control, allocation, and management of major river systems in Texas in support of a variety of water resources planning and management activities. This paper presents a comparative review of river/reservoir system modeling capabilities that integrates the Texas experience with nationwide endeavors to develop and implement generalized models. The enormous published literature on reservoir/river system models is complex. This state-of-the-art assessment begins with a broad general review of the massive literature and then focuses on generalized modeling systems that have been extensively applied by water management agencies in a broad spectrum of decision-support situations in Texas and elsewhere. Several modeling systems are suggested as being representative of the state-of-the-art from a practical applications perspective. Modeling capabilities are explored from the perspectives of types of applications, computational methods, model development environments, auxiliary analyses, and institutional support. The paper highlights advances in modeling complex river/reservoir system management issues that are significantly contributing to actual practical improvements in water management.