This study seeks to derive an original multicriterial decision making model for operative control of water quality in the water reservoir. The model design is based on the theory of dynamic systems control. It incorporates simulation modelling methods with the hydrodynamic reservoir and multicriterial optimization methods. The research aims to derive an algorithm for operating rules of the reservoir under any operating conditions and for the given criteria of control. The study presents the outcomes of the application of model quality control of water withdrawal from the Rimov reservoir on the Malše River.