The article considers the long-term (1941-2018) transformation of the Krasnodar valley reservoir,the largest in the North Caucasus.The main functions of the Krasnodar res-ervoir are irrigation of rice systems and flood protection of land in the Krasnodar reservoir region and the Republic of Adygea.According to topographic maps,Landsat satellite images(1974-2018) and field observations (2016-2018),four stages of transformation of the flood-plain reservoir are identified.The selected stages are characterized by both natural causes(the transformation of the filling deltas into the extended deltas,etc.) and man-made causes(runoff diversions in the delta areas,etc.).The key factor of transformation is the formation of deltas of rivers flowing into the reservoir.Each of the selected stages,against the background of a gradual reduction in the area and volume of the reservoir,is characterized by the pecu-liarities of the formation of river deltas with the formation of genetically homogeneous sections of delta regions.During the period of operation of the reservoir,the delta of the main Kuban River moved up to 32.4 km and took away an area of 35.4 km2 of the reservoir.During the formation of the deltas of the Kuban and Belaya rivers,a bridge was formed on the Krasnodar reservoir.The evolution of the delta regions led to the division of the reservoir into two au-tonomous reservoirs.The total area of the delta regions was 85.9 km2 by 2018,i.e.,21％ of the initial area of the reservoir.The transformation of the Krasnodar reservoir leads to a de-crease in its regulated volume and gradual degradation.