Abstract
The work studied the general ecological state of Lake Bolshoy Sarykol in the east of the Abay district of Karaganda region. Morphometric measurements of the reservoir, studies of samples for hydrochemical composition, composition of bottom sediments, diversity and quantitative indicators of coastal aquatic vegetation, diversity and quantitative indicators of phyto- and zooplankton, benthic organisms and fish populations were carried out. The results of studying the content of sulfates in bottom sediments and mobile sulfur indicate active sulfate reduction. According to hydrological data, the lake of the steppe zone Bolshoy Sarykol is experiencing its high-water period. The water in the lake is slightly brackish, sodium-hydrocorbanate-chloride type, the acidity is neutral, slightly alkaline without harmful impurities, favorable for fishery reservoirs. The species diversity of Lake Bolshoy Sarykol is mainly represented by widespread species of planktonic and benthic organisms, nekton and determines the mesotrophic type of trophism, as well as the β-mesosaprobic type of eutrophication. The results of the work can be useful for the development of measures and recommendations aimed at the rational use and protection of water resources in the Karaganda region, since the studied water body is a typical lake for this region.