Water quality models are used in conducting evaluations of waste loads from point and nonpoint sources and in pollutant exposure assessments. To encourage the wider application of these techniques, the Office of Research and Development of the U.S. Environmental Protection Agency established the Center for Water Quality Modeling to provide a focal point for water quality modeling activities. The Center supports several modeling techniques and computer programs for water quality analysis ranging from techniques appropriate for preliminary analysis to sophisticated models for detailed planning. The paper describes the models supported by the Center and presents an overview of the Center's activities, which include distribution and maintenance of computer programs, training of users, and sponsorship of a users group.