Abstract <p>The water availability in the subjects and federal districts of the Russian Federation during the periods of stationary and non-stationary climatic conditions is evaluated. The hydrological and hydrochemical data from meteorological stations and observation sites in the basin of the Lower Don are summarized, which makes it possible to assess the long-term variability of water quality based on the specific combinatorial index of water pollution, taking into account anthropogenic load and climate change. Some ways to stabilize water scarcity and to increase natural water availability are proposed.</p>