Assessment of the ecological state of water bodies of the drainless area of the Ob-Irtysh River basin

Aim. Assess the current state of water bodies, compare with retrospective study data, update the bank of hydrological, hydrochemical and hydrobiological information.Material and Methods. Three groups of indicators were used: hydrological, hydrochemical and hydrobiological. Hydrological measurements were carried out to determine the flow of water in the rivers and their sections not covered by the Roshydromet observation system. Hydrochemical analysis of samples was carried out by ion chromatography and spectrophotometry and included the determination of basic cations and anions, organic substances and biogens. The assessment of water quality by hydrobiological indicators was carried out using the structural characteristics of phyto- and zooplankton.Results. According to environmental and sanitary indicators, the water quality of only three rivers - Solonovka, Cheremshanka and Burla (downstream) - belongs to class 4 (polluted waters). Most of the rivers have the 2nd class of water quality (clean).Conclusions. A trend towards an increase in the level of mineralization and metamorphization of the chemical composition of natural waters in the inland region of the Ob-Irtysh interfluve was revealed. The pollution of water bodies with organic substances and biogens was noted.