The paper considers the application of estimation, forecasting, and control techniques to the problem of combined real-time control of stream discharge and water quality in a river basin. A simple recursive  estimation procedure is presented for the on-line estimation of pollutant movement and dispersion in a reach of a river. Some important features  of the linear multivariable control system design problem are then considered in the context of controlling downstream discharge and quality given an upstream effluent discharge and surface storage facility as input control variables. Because of the very basic difficulties of visualizing water quality regulation according to most conventional control engineering approaches, a final section of the paper offers a speculative examination of the possibilities for fuzzy control applications in operational river basin management.