This paper examines specific runoffs in the catchments of the rivers Ina, Rega, Parsęta, Radew and Wieprza in the hydrological years 1981 through 2019. The magnitude of specific runoff is an indirect measure of water resources in a given region. Except for the Radew catchment, mean annual specific runoffs have diminished in all the analyzed catchments through the study period. In some or all of the catchments, runoffs from April through July have also diminished. The largest changes have been observed for June in the Ina and Parsęta catchments. These changes are basically due to the increase in air temperature.