The Chu is a river in northern Kyrgyzstan and southern Kazakhstan. Of its total length of , the first 115 kilometres are in Kyrgyzstan, then for 221 kilometres the river serves as the border between Kyrgyzstan and Kazakhstan and the last 731 kilometres are in Kazakhstan. It is one of the longest rivers in Kyrgyzstan and in Kazakhstan. It has a drainage basin of .
History
thumb|right|Chu River in the Syr Darya basin
The area of this river was originally home to the Iranian Sughds who spoke Soghdian, an Eastern Iranian language.
During the Middle Ages, the area was strategically important. It was the setting of Suyab, the capital of the Western Turkic Khaganate and Balasagun, the capital of the Qara Khitai (Western Liao dynasty).
The Chu River posed a risk of flooding for settlements located in the Chu Valley. In the winter of 1878, an ice gorge formed on the Chu River upstream from Tokmok, the administrative centre of Semirechye Province. This was followed by severe flooding that damaged the town and the province's capital was moved to Pishpek (Bishkek).
Dams
The river flow is regulated by the dam at Orto-Tokoy Reservoir in Kyrgyzstan built in 1957 and the dam at Tasotkel Reservoir in Kazakhstan built in 1974.
Ecology and environment
Environmental monitoring
The Kyrgyz State Agency for Hydrometeorology and the Kazakhstan Hydrometeorological Service (Kazhydromet) operate a number of water quality monitoring stations on the Chu River and its tributaries.
Water quality
According to the Kyrgyz State Agency for Hydrometeorology, in 2004–08 the water pollution index of the Chu River in the Chu Valley ranged from 0.25 to 0.7 units, which is interpreted as Class II ("Clean water"). The only exception was a monitoring point downstream of Vasilyevka village where the water pollution index ranged from 0.4 to 1.2 units and water quality was assessed as Class II(Clean)/Class III ("Moderately polluted").
Major tributaries
In Kyrgyzstan, 4892 rivers and canals flow into Chu River. The main tributaries are, from source to mouth:
- Kochkor (left)
- Joon Aryk (right)
- Chong-Kemin (right)
- Kichi-Kemin (right)
- Kara-Konguz (right)
- Shamshy (left)
- Ysyk-Ata (left)
- Alamüdün (left)
- Ala-Archa (left)
- Jylamysh (left)
- Kakpatas (right)
- Ak-Suu (left)
- Kuragaty (left)
Gallery
<gallery>
Image:E8145-Chu-River.jpg|In the Boom Gorge
Image:balbal.jpg|A medieval balbal near Burana Tower in the Chüy Valley
Image:E8046-Chuy-Valley-Milyanfan-east.jpg|In the Chüy Valley near Milyanfan
Image:E7858-Korday-Chu.jpg|Near Korday border crossing
Image:E7840-Shu-city-river-crossing.jpg|Near Shu, Kazakhstan
</gallery>
See also
- Chu-Ili Range