Chirkuo

The Chirkuo (Чиркуо) is a river in Yakutia (Sakha Republic), Russia. It is a right hand tributary of the Vilyuy, and is 118 km long —206 km including the Duikhta at its head, with a drainage basin of 7710 km2.

In the Ust-Chirkuo Site (Чиркуо төрдө) there are remains of ancient settlements by the river. Currently there are no permanent inhabited places in the river area.

Course
The Chirkuo lies in the upper stretch of the Vilyuy basin. It begins at the confluence of the Duikhta and the Kucchuchi-Chuurka (Куччучи-Чуурка) in the Vilyuy Plateau. The river flows roughly northwards across the plateau along the border with Irkutsk Oblast to the west. Finally it meets the right bank of the Vilyuy 1712 km from its mouth in the Lena. The river freezes between mid October and late May.

The main tributaries of the Chirkuo are the 120 km long Golusakh and the 88 km long Dulisma from the left. The last stretch and mouth area of the Chirkuo are part of the backwater of the Vilyuy Reservoir.

Fauna
The waters of the Chirkuo provide a habitat for the critically endangered Siberian sturgeon.