Completion of Subansiri Lower Hydroelectric Project Expected by March 2024

The Subansiri Lower Hydroelectric Project is nearing completion, with expectations to finish by March 2024. The project includes a flood cushion to manage normal flood conditions. Currently, four of the eight generating units are operational, with more units expected to come online soon. The reservoir's design allows for effective water management during the monsoon season, although extreme rainfall could still lead to downstream flooding. This article explores the project's progress and its implications for flood management in the region.

By Narendra Chaudhary Jul 12, 2026, 09:17 IST

Overview of the Subansiri Lower Hydroelectric Project

A file image of Subansiri Lower Hydroelectric Project (SLHEP). (AT Photo)

Guwahati, July 12: The Subansiri Lower Hydroelectric Project (SLHEP) is on track for completion by March of the upcoming year. This initiative will incorporate a flood cushion designed to effectively manage typical flood conditions.

In a discussion with a local media outlet, AN Mohammed, the project's technical consultant, revealed that four out of the eight generating units are currently operational. The fifth unit is anticipated to be operational by August, while the sixth unit is expected to be ready in the next few months.

The reservoir boasts a storage capacity of 1,365 million cubic meters. To accommodate normal rainfall during the monsoon season, approximately 15 meters of storage will be kept vacant, allowing it to absorb excess water.

According to Mohammed, the Subansiri River has the capacity to safely transport around 7,000 cubic meters of water per second. The project's water releases from the reservoir will be managed with this capacity in mind during the rainy season.

However, he noted that in cases of exceptionally heavy rainfall, downstream flooding may still occur, and the project should not be held accountable for such events. Historical data indicates that rainfall of this severity typically occurs once every decade.

During winter, the reservoir will remain at full capacity due to minimal rainfall. In the lean season, most generating units will be inactive during the day to allow water to accumulate, with operations ramping up during peak demand hours from 5 PM to 10 PM.

When asked about the water overflow from the Ranganadi and Kurichu dams in Bhutan, which leads to downstream flooding, Mohammed explained that these projects have smaller reservoirs. Consequently, during heavy rainfall, these reservoirs fill quickly, resulting in water spilling over and contributing to flooding downstream.