During floods part of Chu water would reach the lake, but such outflow has not been seen since the construction of the Orto-Tokoy Reservoir.

After passing through the narrow Boom Gorge (Russian: Боомское ущелье, Boomskoye ushchelye), the river enters the comparatively flat Chüy Valley, within which lie the Kyrgyz capital Bishkek and the Kazakh city of Shu.

In wet years it may reach the endorheic salt lake Akzhaykyn, located among the vast solonchaks of the Ashchykol Depression.

In the winter of 1878, an ice gorge formed on the Chu River upstream from Tokmok, the administrative centre of Semirechye Province.

Such water quality parameters as biochemical oxygen demand, nitrites, copper, and phenols exceeded the maximum allowable concentrations.