After a 20-year wait, the Subansiri Lower Hydroelectric Project has commenced power generation, with one unit synchronized to the national grid at 6:12 pm yesterday. Managed by NHPC, the 2,000-MW project consists of eight 250 MW units, two of which are operational. Three additional units are anticipated to launch this month, aiming for full project completion by March 2027. Project consultant A.N. Mohammad emphasized that this milestone marks significant progress in India’s hydropower sector, with an expected 1,000 MW more coming by December 2025.
Initially conceived in 2005 along the Arunachal–Assam border, the project endured an eight-year delay due to protests concerning dam safety and ecological impacts downstream. In response, the Centre formed expert panels that recommended enhancements to the dam’s structure, including seismic design improvements, seepage-control barriers, and stricter ecological regulations, including a mandated environmental flow of 240 cubic metres per second to protect the river’s ecosystem.
The reservoir can hold 1,365 million cubic metres with a designated flood cushion and is designed to aid in flood moderation. Upon full operation, the project will produce 7.421 billion units of renewable energy yearly, providing Assam with an additional 300 MW of electricity and 25 MW free, while Arunachal Pradesh will receive 12% of the generated power. Due to delays, the project’s cost has risen to approximately ₹26,000 crore.
