Experience of the flood in 2010 showed that the effectiveness of flood protection means and activities undertaken so far in the Dłubnia river basin is not sufficient. Therefore, there some additional measures are required for its improvement. The subject of this study is to analyze the possibility and effectiveness of application of uncontrolled flood storage reservoirs on the Dłubnia river located upstream the Zesławice reservoir. Six possible locations of reservoirs were analyzed. For each of them the capacity curve was defined and the parameters of the outlet structures were calibrated so as to obtain maximum reduction of flood wave culmination of Q1%. The numerical simulations were conducted on a computer model built on the basis of the MIKE 11 by DHI program for hypothetical flood scenarios: Q50% Q10%, Q1% and Q0.2%. The analysis of effectiveness was performed basing on a comparison of results of the Dłubnia river models with the reservoirs included and without them. The influence of the analyzed solutions to the flood wave outflow conditions was performed in terms of flood risks reduction in the river Dłubnia catchment and conditions of the Zesławice reservoir functioning.