|Difficulty in September:||3-4|
|From:||Kok-Moinok - Alt. 1520 m (4850 ft)|
|To:||Djil-Aryk - Alt. 1280 m (4200 ft)|
|Distance:||28 km (17 miles)|
|Average Gradient:||8 m/km (40 ft/mile)|
|Est. Max Gradient:||10-15 m/km (50-75 ft/mile)|
|Typical Flow in September:||40-50 cms (1400-1800 cfs)|
|Kara-Kudjur and Djoon-Aryk|
|Difficulty in September:||3-4|
|From:||Ak-Kya - Alt. 2470 m (8100 ft)|
|To:||Kochkorka Dam - Alt. 1840 m (6040 ft)|
|Distance:||45 km (28 miles)|
|Average Gradient:||14 m/km (70 ft/mile)|
|Est. Max Gradient:||15-20 m/km (75-100 ft/mile)|
|Typical Flow in September:||10-20 cms (350-700 cfs)|
The Chu is an easy river (by Tien-Shan's standards), flowing through most populated areas of Kyrgyzstan, so sense of wilderness is limited, but access to the river is easy.
The source of the river, named Kara-Kudjur, is located south of Issyk-Kul Lake, the biggest lake of the Tien-Shan. The upper river flows west in a small valley, until it meets one of the major roads, the Bishkek-Naryn route, at the village of Sarybulak. It changes its name to Djoon-Aryk here, and starts to make big arch to the north, to exit into huge flat basin near large town of Kochkorka. Kara-Kudjur and especially Djoon-Aryk flow in quite narrow valleys and have nice whitewater sections.
At Kochkorka the river changes its name once again and finally becomes Chu. It is completely flat here with occasional class 2 gurgles; to be more kayak-friendly it has a 15 km reservoir before a powerhouse at Orto-Tokoi. Below that it makes another big arch to the west, passing by Issyk-Kul Lake (it's just 7 km away from the shore but there's no connection between the river and the lake).
Having passed Issyk-Kul, the Chu gradually enters a narrow gorge, known as the Boom Gorge that cuts through Kyrgyz Range all the way down to the plains and the Bishkek city. Due to its proximity to the capital and big raft-friendly whitewater, the Boom Gorge is very popular for short (1-2 days) commercial rafting trips.
Access & Logistics
The Boom Gorge is the major route connecting Bishkek and numerous towns and resorts on the shores of sacred Issyk-Kul. There's a good road and even a railway to the main town, Balykchi (Rybachye) on the west end of the lake. The road continues further up the river, through Kochkorka to Sarybulak, where it leaves (now) Kara-Kudjur valley and goes south to the town of Naryn, administrative center of the so-called Inner Tien-Shan.
Above Sarybulak a local road goes all the way up the Kara-Kudjur and finally crosses to upper Smaller Naryn valley.
There's little reason to run the whole river, as its middle stretches are completely flat for nearly 100 km and there're no great landscapes here either.
The put-in for the Boom Gorge is around a rail station of Kok-Moinok, some 6-7 km above the place where both road and the railway cross the river (there's only one rail bridge in the gorge); higher up the valley opens and the river becomes pretty much flat. Take-out is possible only after the river exits a canyon near Chong-Kemin confluence; look for appropriate place on the way up (if you drive from Bishkek). First village and a rail station with easy river access is Djil-Aryk, 7-8 km below the Chong-Kemin confluence.
The put-in for the upper river (Djoon-Aryk and Kara-Kudjur) is a small village of Ak-Kya, some 20 km upstream of Sarybulak (where main road leaves the river and goes south to the Naryn town); higher up the river flows in a flat open basin. Alternatively, you can start just near Sarybulak, as the section above is reported as quite small and easy (mostly class 2-3). Take-out is possible anywhere in the Kochkorka basin; most obvious place is near an irrigation dam, located just as the river exits the mountains.