A deterministic approach which avoids extreme failures in the management of a multipurpose reservoir is presented and discussed in the paper. The main feature of the method is to suggest a whole range of possible decisions which guarantee the efficient performance of the system. This allows the manager to choose the release which better fits with the additional informations or forecasts he might have, as well as to accommodate for secondary objectives which were not considered in the formulation of the problem. The results of the application of this approach to the management of Lake Como (Northern Italy) favorably compare with those obtained by a more traditional stochastic optimal control formulation and with the historical data.