Data on the current radioecological situation in the Techa-Iset' river syst
em, which was contaminated by radioactive wastes from the Mayak Production
Association in the 1940s and 1950s, are discussed. Mathematical models are
presented that describe the decrease in the contamination of water, bottom
sediments, hydrobionts, and floodplain soils with an increase in the distan
ce from the discharge site. The amounts of Sr-90, Tc-99, (13)7Cs, and trans
uranium elements in the main components of the ecosystem are estimated.