Author: PPD Team Date: 02/07/2025
NHPC Limited is awaiting final clearance from the National Dam Safety Authority (NDSA) to begin commercial operations of the first three units—each of 250 MW—of the Subansiri Lower Hydroelectric Project. The update was confirmed by NHPC on June 30, 2025, as reported by Assam Tribune.
The long-delayed, high-stakes project on the Subansiri River near North Lakhimpur—at the border of Assam and Arunachal Pradesh—has already consumed over Rs 90 billion and more than two decades of planning and political turbulence.
The project consists of eight generating units of 250 MW each. NHPC had earlier targeted commissioning of the first three units by June 2025, with the remaining five units scheduled in phases by May 2026. However, as per latest report by Central Electricity Authority (CEA), five units (1,250 MW) are expected during 2025–26, and three units (750 MW) in 2026–27.
Subansiri Lower faced long delays due to local opposition. Construction was suspended from December 2011 until October 2019 following protests over seismic and environmental concerns. The impact of years of delay is evident in cost overruns. When proposed in 2005, the project was expected to cost Rs 6,285 crore. It is now estimated at nearly Rs 26,000 crore.
The dam design underwent several revisions addressing foundation safety, seismic risks, and ground conditions. After these were approved in 2014, NHPC resumed bidding and civil works. Major contractors involved include Patel Engineering and Texmaco Rail & Engineering.
NHPC has completed dam construction to the top level of EL 210 metres and commissioned key equipment like the 250-MT Spillway Bulkhead Gantry Crane.
The project’s estimated annual generation is 7,421.59 million units (MU) in a 90 per cent dependable year. Power allocation has been finalised: Assam will receive 533 MW, Arunachal Pradesh 274 MW, and the remaining northeastern states 198 MW collectively. Northern states such as Haryana, Punjab, Uttar Pradesh, Rajasthan, and Chandigarh will receive 387 MW, while 613 MW will be supplied to western states including Gujarat, Maharashtra, Madhya Pradesh, Chhattisgarh, and Goa.
The central government also sanctioned a Rs 4.7 billion downstream development package in 2022 to mitigate project impact, including bank protection, development activities, and awareness programs.