Assam: Subansiri river dries up, concerns over impact of Subansiri Lower Hydroelectric Power Project, India’s largest hydro power project

A landslide in the upper reaches of the Subansiri river which has blocked one of the 5 diversion tunnels of the Subansiri Lower Hydroelectric Project has once again raised serious doubts about construction of a dam on a river which may have far reaching implications in the days to come.

Out of the five diversion tunnels, only diversion tunnel No 1 which was in use in the power project, was blocked due to landslide that occurred around 11:30 am on Friday.

The other four diversion tunnels had already been blocked earlier after construction works were complete. As a result, the river flow to the downstream has been highly reduced.

An unprecedented situation now prevails in south of Assam where the Subansiri river has dried up which has already raised an alarm in the downstream areas of Dhemaji and Lakhimpur districts. The situation is such that the river bed is now visible at certain locations. The common people as well as groups, organisations and environmentalists are deeply concerned about what is happening.

The aquatic life has also been adversely affected owing to the situation arising out of the tunnel blockade in the Hydroelectric power project. Thousands of fish have died so far due to the river drying up.

A resident along the banks of the Subansiri river in downstream said, “It will be wrong to think that the river will become normal since experts have said that if a river dam project comes then during winter when there will be more necessity of water to generate power, then when the dam gates would be shut, the flow of the Subansiri river will reduce. This has been proved yesterday. The aquatic life, migratory birds have been severely affected. If plans are not revoked than we the people in the downstream will have the same situation every winter.”

Subansiri Lower Hydroelectric Project (SLHEP) is an under-construction gravity dam with a power generation capacity of 2000 MW (8×250 MW). This run of river project is the biggest hydroelectric project undertaken in the entire nation. Nearly 90% of the project has already been completed and it is likely to be commissioned by next year.