Biryusa is a river 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:...

, 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...

. The Biryusa is 1,012 km long, with a drainage 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...

 of 55,800 km².

The river has its sources in the far southwestern areas of Irkutsk Oblast, at 2,500 meter altitude, on the northern slopes of the Sayan Mountains

Sayan Mountains

The Sayan Mountains are a mountain range between northwestern Mongolia and southern Siberia, Russia.The Eastern Sayan extends from the Yenisei River at 92° E to the southwest end of Lake Baikal at 106° E...

. From the source area the river flows north over the Central Siberian Plateau

Central Siberian Plateau

The Central Siberian Plateau is made up of sharply demarcated surfaces of varying altitudes occupying most of Siberia between the Yenisei and Lena rivers. It extends over an area of 3.5 million km². The highest point is the Putoran Mountains rising to 1701 m. To the north of the plateau are...

. It is crossed by the Trans-Siberian railway

Trans-Siberian Railway

The Trans-Siberian Railway is a network of railways connecting Moscow with the Russian Far East and the Sea of Japan. It is the longest railway in the world...

 at Biryusinsk

Biryusinsk

Biryusinsk is a town in Irkutsk Oblast, Russia, located on the right bank of the Biryusa River , northwest of Irkutsk. Administratively, Biryusinsk is under the jurisdiction of the nearby town of Tayshet. Population:...

, which is a few kilometers west of Tayshet

Tayshet

Tayshet is a town and a railroad junction in Irkutsk Oblast, Russia. Population: Here the Baikal Amur Mainline begins, branching northeast from the Trans-Siberian Railway...

 where the Baikal Amur Mainline starts. The Biryusa then turns northwest, and finally flows together with the Chuna River

Chuna River

Chuna above the settlement Chunsky) is a river in Irkutsk Oblast and Krasnoyarsk Krai of Russia. It is long, with a drainage basin of 56,800 km²....

 and forms the Taseyeva River

Taseyeva River

right|thumb|250px|Angara and Upper YeniseiTaseyeva is a river in Krasnoyarsk Krai, Russia. It is a left tributary of the Angara River, and is 72 miles long...

 (a tributary to the Angara

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....

).

In Russian folklore it has several songs, for example, "Biryusinka" (in Russian).