Suman River, the only river which took its rise from the lake Terkhiin Tsagaan, flows south of Khorgyn Togoo along the extreme north of Tariat soum, Arkhangai Aimag and passes swiftly through large volcanic rocks. It drains into Chuluut River after flowing for about 60km. This lake flows through 30-40m wide, 10m high canyon. The average flow rate is 11,3m/sec. This river is rich in waterfalls. Northern Terkh River is regarded to be a source of the Suman River. There are many volcanic rocks as well as a rich source of gemstones in the river basin. Since the river never freeze, hundreds of ducks, few swans and geese inhabit around it regardless of season.