The Kazakh lake with fresh water in its west and saline water in its east is Lake Balkhash.
Lake Balkhash lies in southeastern Kazakhstan within the closed Balkhash–Alakol Basin. A narrow strait near the centre divides its western and eastern sections. The western basin is broader and comparatively shallow, receiving most of the inflow from the Ili River; the eastern basin is narrower, deeper and saltier because evaporation concentrates dissolved minerals.
Unlike an ordinary lake connected to an ocean-draining river system, Balkhash is endorheic: its rivers flow into the lake, but no river flows out. The Ili supplies most of the water, while the Karatal, Aksu, Lepsy and other rivers provide additional inflow. Water diversion and industrial use have raised concerns about shrinking levels and ecological damage.
Lake Balkhash is often confused with nearby Lake Alakol, another major Kazakh lake in the same broad region. Balkhash is about 605 kilometres long, but its width varies sharply between the western and eastern basins. The city of Balkhash, on the lake’s northern shore, is an important local mining and fishing centre.