Kasansay (Kyrgyz: Kasan-say, Uzbek: Kosonsoy)
A river in Kyrgyzstan and Uzbekistan, a right tributary of the Syr Darya. In its upper reaches, it is called Chalkydysay.
Length — 127 km, basin area 1780 km². It originates on the southern slope of the Chatkal Range in the Western Tian Shan.
It flows initially in a narrow mountain valley, and in its lower reaches enters the Fergana Valley. Approaching the Fergana Valley, the river turns south, crosses the border between Kyrgyzstan and Uzbekistan, flows through the city of Kasansay (in the Namangan region of Uzbekistan), continues southward, passes through the city of Turakurgan (also there) and turns west towards the regional center of Namangan to the Syr Darya.
The average annual water discharge at the village of Baymak (52 km from the mouth) is 11.6 m³/sec. Further downstream, it is used for irrigating agricultural lands.
The Kasansay River in the Jalal-Abad region of Kyrgyzstan has the Kasansay Reservoir built on it, and to the west of the village of Orto-Tokoy, the Orto-Tokoy Reservoir was constructed in 1960 on the border of the Naryn and Issyk-Kul regions.
