The closed Lake Balkhash is situated in a land depression of tectonic origin. The orography of its drainage basin is very complex: there are high mountain systems, low mountains, plains, and sands partly bordering the lake. The Balkhash depression is under the influence of arid continental climate with annual precipitation less than 150-200 mm. There is semi-dessert vegetation along the lake shore. The area and water volume of the lake vary considerably in due course depending on the large amplitude of long-term and secular fluctuations of its water level. For example during our century its water surface has changed from 15,730 km² (1946) to 23,464 km² (1910) and its water volume from 82.70 km³ to 163.9 km³.

The difference between the eastern and the western parts of the lake basin is essential. There are 58% of the total water surface and 46% of the lake water volume in the western part. The mean depth of the eastern part is 1.7 times more than those of the western part. The western part of the lake has fresh or slightly salty water (0.5% 1.5%) depending on the secular fluctuation of its water level, while the eastern part is characterized by rather high concentration of dissolved solids (up to 7%). The main reasons for such a difference are the inflow of a huge river to the western part and the retarded exchange of water between the two parts.

Balkhash is very important for its utilization. The water resources of the lake and its tributary rivers are used for irrigation, municipal and industrial water supply (including the supply for the Balkhash Copper Melting Plant). The fish catch in the lake is also very important for the Kazakhstan.

During the latest years, the problem of Balkhash Lake became more explicit because of the start of the filling of Kaptchagayskoye Reservoir (with a volume of 29 km³) on the River Ili. The filling of the first 14 km has resulted in negative consequences on the water level, water-salt balance and ecology of the lake. The main problem is how to harmonize natural-ecological conditions of this lake with the need of a reservoir for irrigation, water supply and hydropower production (Q).