Dammed water reservoirs for drinking water production with their catchment areas and rivers downstream represent dynamic systems that change constantly and are subject to many influences. An optimized management considering and weighing up the various demands on raw water reservoirs (long-term storage for drinking water supply, flood control, ecological state of the rivers downstream, energy production, nature conservation and recreational uses) against each other is therefore very difficult. Thus, an optimal reservoir management has to take into account scenarios of possibly occurring external influences and to permit predictions of prospective raw water qualities, respectively. Furthermore, the impact of short and long term changes in raw water quality on subordinate processes should be considered. This approach was followed in the work presented here, as there currently is no tool available to predict and evaluate the impacts of raw water reservoir management strategies integratively. The strategy supported by the newly developed decision support procedure takes into account all aspects from water quality, flood control and drinking water treatment to environmental quality downstream the reservoir. Furthermore, possible extreme events or changes of boundary conditions (e.g. climate change) can be considered.