Ilim River is a river

River

A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...

 in Irkutsk Oblast

Irkutsk Oblast

Irkutsk Oblast is a federal subject of Russia , located in southeastern Siberia in the basins of Angara River, Lena, and Nizhnyaya Tunguska Rivers. The administrative center is the city of Irkutsk. Population: -History:...

 in Russia

Russia

Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

, a right tributary of the Angara River

Angara River

The Angara River is a long river in Irkutsk Oblast and Krasnoyarsk Krai, south-east Siberia, Russia. It is the only river flowing out of Lake Baikal, and is the headwater tributary of the Yenisei River....

. It flows north between and parallel to the Angara and Lena River

Lena River

The Lena is the easternmost of the three great Siberian rivers that flow into the Arctic Ocean . It is the 11th longest river in the world and has the 9th largest watershed...

s, and then swings west to join the Angara 40km south of Ust-Ilimsk

Ust-Ilimsk

Ust-Ilimsk is a town in Irkutsk Oblast, Russia, located on the Angara River. Population: 53,000 .-History:An ostrog was built on the present site of the town in the 17th century; however, the modern town was not founded until 1966, during the construction of the Ust-Ilimsk Hydroelectric Power...

.

The Ust-Ilimsk Dam on the Angara (downstream from the older, bigger, and better known Bratsk Dam), completed in the mid-1970s, not only backs up the Angara, but also the Ilim as far as Zheleznogorsk-Ilimsky

Zheleznogorsk-Ilimsky

Zheleznogorsk-Ilimsky is a town and the administrative center of Nizhneilimsky District of Irkutsk Oblast, Russia, located east of Bratsk and west of the northern tip of Lake Baikal, from the Ilim River and north of Irkutsk...

. The site of the old town of Ilimsk

Ilimsk

Ilimsk was a small town in Siberia, within today's Irkutsk Oblast of Russia. The town was flooded by the Ust-Ilimsk Reservoir in the mid-1970s....

 was flooded by the reservoir.

The length of the Ilim is 589 km. The area of its basin

Drainage basin

A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

 is 30,300 km². The river freezes up in late October and stays icebound until early May. Its main tributaries are the Kochenga, Tuba, and Chora Rivers. See also Siberian River Routes

Siberian River Routes

Siberian River Routes were the main ways of communication in the Russian Siberia before the 1730s, when roads began to be built. The rivers also were of primary importance in the process of Russian exploration and colonisation of vast Siberian territories...

.