Syr Darya

River in Central Asia, which is formed by headstreams that rise in the Alay and Tien Shan mountain ranges. The Syr Darya flows northwest for 2,212 km/1,375 mi through Kyrgyzstan, Uzbekistan, and Kazakhstan before emptying into the Aral Sea. Its tributaries are used for irrigation; on its course the river passes through the very fertile Fergana Valley, and skirts the north of the Kyzyl-Kum desert. Principal towns on its route are Khodzhent and Kyzl-Orda.

Together with the Amu Darya, the Syr Darya supplies water to over half of the cultivated land of the Central Asian republics, and accounts for 90% of the water resources in the Aral Sea basin. As with the Amu Darya, a large proportion of the river's waters has been diverted for irrigation purposes, severely reducing the volume of water supplied to the Aral Sea.