Lake Baikal is one of the oldest fresh water bodies on the planet, where the largest available water reserves are concentrated. River runoff plays an important role in the overall balance of substances entering the Lake. The Selenga River is the main tributary of Lake Baikal, in the basin of which, unlike other tributaries, a large number of industrial, agricultural, processing enterprises, settlements and cities are concentrated. The Barguzin River is the third largest river flowing into Lake

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... aikal, is the basin where intensive development in agriculture and forestry has undertaken. This paper presents the results of the analysis of surface water samples of the Selenga and Barguzin rivers collected during 2015-2016. In 2015, the water level for the Selenga and Barguzin rivers was characterized by extremely low water content, which caused an increase in the concentrations of major ions and trace elements in surface waters. The more favorable water regime in 2016 caused a significant decrease in ion concentrations. Maximum concentrations of iron and manganese are observed in winter and during flooding in the spring. In conditions of low water content, increased copper and zinc contents were also observed in the surface water of the Lake tributaries.