Hasdeo River is the largest tributary of Mahanadi River. The river flows in the state of Chhattisgarh. It joins Mahanadi River near Shiladehi (Birra). Hasdeo Bango Dam is constructed across this river. The river originates about 910.0 m (2,985.6 feet) above sea level, in a place about 10.0 km (6.2 miles) from Sonhat in Koriya district. The total length of the river is 333.0 km (206.9 miles), and drainage area is 9856 km2. The major tributary of Hasdeo River is Gej River.
