Sarayu, the lifeline of lakhs of people in Bihar and Uttar Pradesh, is choking to death.

The once 1.5km-wide river has narrowed down to 30-40m owing to a combined assault of global warming, pollution, construction of the Pancheshwar dam in Nepal and shifting of its course.

The receding water-level is also threatening its tributaries and adversely affecting agriculture in the area around the river. Thousands of acres of fertile land in the diara (riverine) areas have been rendered barren because of accumulation of sand after the river changed its course.

Water table in the adjacent areas has dropped and thousands of hand pumps have dried up. Residents are facing acute drinking water problem.

Sarayu originates from Mansarovar in the Himalayas and is also known as Ghaghra and Manas Nandini. It merges with river Ganga in Saran district near Doriganj, 15km from the district headquarters. During the Mughal and British era, cargo ships were anchored here. Consignments from Calcutta were dumped at Manjhi, Rebelganj, Sahebganj, Daulatganj and Doriganj. However, the receding water-level has been a cause of great concern and hand pumps with less than 200-ft submerged pipes have dried up. Tel and Sondhi rivers have also dried up.

The mahant (chief priest) of Ram Mandir at Rebelganj, Ramji Das, 80, told The Telegraph: “The river used to be very wide when I came here in the 1960s. But today, all I see is sand. The river has shifted northwards by around 2km. Even the current in the narrowed river has slowed drastically.” “The danger to its existence is a threat to our culture, as religious sentiments are attached with this river,” he added.

S.N. Singh, teacher in the zoology department, Jai Prakash University, said: “The construction of Pancheshwar dam in Nepal has reduced the flow of water in the river. Pollution has also increased which is proving dangerous for aquatic life.” He added that the dipping water-level has also endangered the existence of dolphins in Sarayu.

Former head of the department of geography Rajendra College R.N. Thakur said: “Sarayu river is in its third stage in this district. That is why the flow is weak. Deposition of silt is another reason that causes the river course to change. The river is drying up as the water-level is receding.”