Ider River outflows by Otgontenger Mountain that joins to Tosontsengel, Ikh-Uul Mountain and Khuvsgul Aimag. It is 455km long with an area of 24555 square meters. The average annual water consumption in the middle part is 36.41 cubic meter / seconds, and at one time can reach 54.4 cubic meter / sec. Chuluut, Khojuul, Zart, Top down Tsetsuut, Khunjil all flow into the Ider River. It freezes from October to April and has many kind of fishes, especially taimen.