The Ganga rises in the Garhwal Himalaya from the Gangotri Glacier, some 4100 meters above the sea level under the name of Bhagirathi. The river flows through the Himalayas till another two streams, the Mandakani and the Alakhnanda join it at Devprayag. It is below this confluence that the river is known as the Ganga proper. The Ganga Basin which is the largest river basin of the country houses about 40% population of India. The river after traversing a distance of 2525 kms. from its source, meets the bay of Bengal at Ganga Sagar in West Bengal. During the course of its journey from the hills to the sea, municipal sewage from large urban centres, trade effluents from industries and polluting waste from several other non-point sources are discharged into the river resulting in its pollution.