Data of long term (1954-1993) hydrochemical studies of rivers of the upper reaches of the Ob' river basin (the Western Siberia, Russia) were generalized. It has been found that the ion-salt composition of water, including HCO3-, SO42-, Cl-, Ca2+, Mg2+, and Na+ + K+ ions and their sum, changed depending on the composition of industrial sewage, volume of annual runoff, water consumption, and also on the hydrological regime of the studied rivers.