Climate change in recent years has caused considerable intensification of rainfall, and as a consequence an increase in flood waves flow rate. This article presents the verifying method of the dam overtopping risk under conditions of enlarged volumetric flood flow rates inflowing the storage reservoir. Values of the flow rate peaks were determined on the hydrological observations basis. The course of the hypothetical flood wave hydrograph was determined on the normalization and averaging basis of the 6 historical flood wave hydrographs. The flood routing analysis through the reservoir was numerically performed, with the assumptions of Puls’s method, for 6 scenarios with 2 flood flow rates and for 3 initial water levels in the reservoir. On the obtained results basis the dam overtopping hazard level was determined, and the necessity for reservoir water management changes was pointed out.