We suggest an integral scheme for assessing the water and sediment discharge in the rivers of the Selenga river basin, based on using expeditionary, network and model data. Assessments are made of the changes in streamflow and in suspended and tractional sediments of the river, and relevant regularities are revealed. A forecast is made of regional changes in water discharge due to anthropogenic development of the territory. It is shown that the expected flow regulation of the Selenga and its tributaries in Mongolia would lead to a reduction in the maximum mean monthly streamflow by up to 14–15 %, and to an increase in the minimum winter flow by up to 73–75 %. Evaporation losses of the discharge from the projected reservoirs, and the water intake for the flow transfer will correspond to a decrease in the water level in Baikal by as much as 1 cm/year. The possible transformation of the territory’s water balance as a result of anthropogenic changes in landscapes during mining operations is investigated in terms of the regional mesoclimate model COSMO_CLM.Keywords: Baikal, reservoir, integral assessment, anthropogenic development of territory, flow regulation, transboundary waters.