This research work is devoted to analyzing the processes of accumulation and distribution of long-lived radionuclides of 90Sr and 137Cs in the components of water-sediment-macrophytes of Lake Malye Kirpichiky (Chelyabinsk region). The characteristic features of redistribution of radioactive substances, depending on the texture of the bottom sediments of the lake and the species composition of aquatic vegetation are shown. Also shown is the total stock of radionuclides in water and bottom sediments. The coefficients of 90Sr and 137Cs accumulation in bottom sediments and macrophytes have been calculated.