The Beas forms the valleys of Kullu and Kangra, famed for their beauty. But ironically, its source is an insignificant looking igloo like structure near Rohtang Pass in Pir Panjal range to the north of Kullu. The main thrust of this river is southward to Larji and then to the west. Where it enters Mandi district and further still into Kangra. On account of its snow-fed, perennial tributaries, its inflow increases greatly during the monsoons, sometimes resulting in floods. At the Pandoh, in Mandi district, the waters of the Beas have been diverted to the Sutlej through 53-km of tunnel, with the Pong Dam constructed on the Beas, for the purpose of increasing the hydroelectric power supply.