Abstract
This article presents the hydrochemical characteristics of Karatal, Ak-Su and Lepsy rivers, hydrological regime and results of hydrobiological research. It also presents the results of studies on the formation of water quality in these rivers at present. As a result, an assessment of the ecological status and water quality was carried out using information and analytical materials from RSE Kazhydromet and Annual data on surface water quality of Kazakhstan. Monitoring was conducted from 2015 to 2020 and included changes in water temperature, dissolved oxygen content, pH values, mineralization levels, as well as main inorganic constituents such as cations and anions. The influence of natural factors on chemical composition of these rivers was also considered.