In the context of the National Spatial Plan, the Preliminary design Flood safety in the Lower Savinjska Valley is in progress. Flood protection is provided by dry reservoirs on the Savinja and Bolska River. Master thesis deals with the optimization of dry reservoirs on Savinja River. Based on the required volumes of retained water that does not threaten areas along the Savinja River downstream from the inflow Bolska, is proposed new design and placement in space. Instead estimated eight reservoirs, master's thesis deals with one bigger, named Šempeter. The Reservoir Šempeter is divided into four parts, which are functionally connected. One is permanently dammed, which can be exploited for purposes of irrigation, recreation or energy utilization. Water balance reservoir is determined with Saga Gis Program. The different heights of the dam presented the necessary quantities of natural materials for the construction of levees. For each reservoir the details of placements in space are shown, necessary infrastructural developments and actual land use. Based on the intake hydrograph, levels of each reservoir are presented as a function of the duration of the flood wave. The intake and outlet structures are dimensioned according to the principle, one field is blocked (n-1). In conclusion, we introduced the findings and comparison with the Preliminary design ensuring flood safety in the Lower Savinjska valley.