Abstract
The Issyk-Kul Lake is one of the largest highland and brackish lakes in continental origin. Assessmentand analysis of the long-term dynamics on the chemical composition of the water in the Issyk-Kul Lakebasin was carried out according to the data for 1932, 1977 and 1986. The average long-term dynamicsof lake water salinity was determined from the data for 1928, 1960, 1980, 2000 and 2014. Sulfates, chlorides,sodium and magnesium are the predominant ions of lake water. Na+ and Mg+ predominate fromthe cations, and from the anions Cl- and SO42-. The sulfates predominate in the chemical composition ofwater, and the lake water belongs to the sulfate class and to the chloride-sulphate-sodium-magnesiumtype of mineralization. The water in the lake has an alkaline reaction and the pH of the lake water waswithin 7.95-8.82 in 2015. The salinity of the Issyk-Kul lake was 6.22 g/l. The study of the hydrochemistryof natural waters is of great practical importance in various branches of the economy. Since the chemicalcomposition of water is taken into account when using natural waters for all types of water supply and water use. The importance of hydrochemical research is also increasing due to pollution of water bodies and anthropogenic activities.