It originates in the Dzungarian Alatau Mountains north of the border with China, and flows into the endorheic Lake Balkhash.

[1] The Lepsy is the easternmost of the two small rivers that flow into the eastern Balkhash on the south bank, the other being the Aksu.

[2] The Lepsy is one of the main rivers of the historic region of Zhetysu.

Lepsy freezes over in December and stays icebound until March.

Because of the amount of water taken for irrigation, the river's flow into Lake Balkash is limited.