The purpose of the paper is the analysis of flow conditions and dams operation for selected weirs located on the reach of the Noteć Bystra river, from the Romanowo dam to the Rosko dam. The study area is chosen due to two reasons: (1) the flood hazard maps were elaborated for this reach, when the EU Flood Directive were applied in Poland in the frame of the ISOK project, (2) along the reach there is several hydro-structures enabling water retention and controlling of the flood wave. The GIS tools and mathematical modeling software is adopted for the purposes of the research. The analysis is done on the basis of flood wave simulation with maximum flows equaling 10% and 1% extreme events. Three variants of dams operation are tested. The results are presented as longitudinal profiles of water surface and inundation maps. The analysis proved that robust control of dams enables reduction of flood hazard in the investigated area.