Balasan River rises in the Himalayas and flows into the Ganges. It is one of the tributaries of the river Mahanadi. It joins with Mahanadi at a point 6.5 km away from Siliguri. The main stream flows down in a zigzag direction southwards through the mountain, offering a scenic view. The two tributaries of Balasan are Rangbang and Rangmuk. The banks of this river form the trekking route from Kurseong to Mirik via Namsu.
Dudhia, a small hamlet on the Mirik-Siliguri highway and Panighata village are on the banks of the Balasan.