Lake Balkhash
The Central Asian lake that is half fresh and half salt
Lake Balkhash is a curiosity of chemistry and geography: a single body of water in southeastern Kazakhstan whose western half is fresh and eastern half is salty. A narrow strait pinches its long, crescent shape almost in two, and on either side the water has settled into strikingly different worlds. One of the largest lakes in Asia, this shallow desert lake is fed mainly by the Ili River from the snowmelt of the Tian Shan, and it has no outlet at all — making it, like the Caspian and the Aral, an endorheic, partly saline lake at the mercy of its rivers.
Balkhash currently covers around 16,400 square kilometres but is remarkably shallow, with a maximum depth of only about 26 metres, so its area swells and shrinks with the seasons and the years. The western basin, diluted by the Ili, stays fresh, while the eastern basin, fed by smaller rivers and concentrated by evaporation, turns brackish to salty. The lake sits in arid steppe and semi-desert, its shores fringed by reeds and its waters supporting a fishery and a chain of wetlands important to migratory birds.
The lake's fate is bound to the Ili, and that is its peril: upstream water use for irrigation and hydropower in both Kazakhstan and China, which controls the river's headwaters, threatens to lower its level much as Soviet diversions destroyed the Aral Sea to the west. Conservationists and the two governments watch the inflow closely, mindful that an endorheic lake can vanish quickly once its rivers are tapped. For now Balkhash endures — a shallow, two-toned inland sea sustaining fishing towns and one of Central Asia's great wetland ecosystems.