The construction of the Kapchagay Reservoir led to the withdrawal of a portion of the water from the river, which reduced the water flow, the situation has gradually been resolved, but the water level in the lake and the flow still need to be monitored. The purpose of the study was to investigate trends in the characteristics showing the state of the ecosystem. A more detailed analysis of changes in meteorological conditions observed in the region according to weather stations revealed significant changes in the water regime and average annual flow of the river. These indicators were obtained at special weather and hydrological stations located along the riverbed and the surrounding area. Climatic changes and anthropogenic factors have had some impact on the flow rate. Rising temperatures and rainfall have affected the glaciers of the Tien Shan Mountain system, increasing the amount of water in the Ili River. At the same time, water intake for agricultural needs had no noticeable effect. Changes in the flow rate are directly related to the biocenosis of the region. The area outlying the river and lake and the delta may become arid due to declining water levels. In this case, the space next to the water will be used more actively. For this reason, it is very important to monitor changes in the flow, as the entire ecosystem depends on the water level. The construction of the Kapchagay Reservoir has certainly had some impact on the water level of the lake and the volume of water flowing into the river, but at this point, the effect of the reservoir has been overridden by the sensitivity of the glaciers. At this point, it is impossible to predict exactly how the situation will unfold, but it is recommended to pay close attention to it.
Keywords: Balkhash Lake; Kapchagay Reservoir; river water flow; delta ecosystem