Abstract
The article considers the use of the Tobol River water resources in Kazakh part of the river basin for the needs of economic complex for the period from 2000 to 2021. The impact of economic activity on the annual runoff and intra-annual flow distribution of the Tobol River near the city of Kostanay for the period from 1965 to 2021 was assessed according to the data of the observation station near the village Grishchenko after the construction of Karatomarsky and Verkhne-Tobolsk water reservoirs. It has been found that during the period of consideration, the average annual water resources of the Tobol River, as well as its spring runoff decreased, and the river runoff in summer and autumn increased compared to the natural period.