Downstream is called the Upper Tunguska River. The Siberian River of the Soviet Union. It originated from the Baikal period, first north, then west, and injected into the Yenisa River. It is 1,779 kilometers long. The basin area is 103 . 90,000 square kilometers. The main support shells are the Irkut River, Kitoi River, Oka River and Ilim River. Hydropower resources are abundant, the average annual flow at the estuary is 4,150 seconds. The main and support are built on the Kirkutsk, Bravok and Usti Ilychensk hydropower stations. Upstream from Irkutsk to Baikal and Blatsk, downstream from Boguchan to the estuary can be navigable for 320 kilometers. Ice period 5-6 months. Main production of quail, quail, jiangyan, frog fish, etc.