The Selenga River (often called Selenge River) is a major river in Asia that forms at the confluence of the Ider and Delger Rivers in northern Mongolia. It flows northeastwards through Mongolia and Russia and forms a large delta on the southeast shoreline of Lake Baikal, the world'slargest and deepest freshwater lake. Tributaries include: Eg River, Dzhida River, Orkhon River, Khanui River, Chikoy River, Khilok River, and Uda River. The Selenga is the primary contributor of water to Lake Baikal, and its tributaries drain approximately 80 percent of the lake's watershed.
The average discharge of the Selenga River into Lake Baikal varies from 100 m3/s in winter to 1,700 m3/s during spring snow melt.