NHPC Ltd, a ‘Navratna’ Enterprise under the Government of India, has declared the commercial operation date (COD) of its first unit (Unit Number 2 of 250 MW) of the 2000 MW (8 X 250 MW) Subansiri Lower H.E. project, located on the Arunachal Pradesh/Assam border. The unit commenced commercial operation on 23 December 2025, marking a significant step in commissioning India’s largest hydropower project.
Union Minister of Power, Housing & Urban Affairs Manohar Lal inaugurated the commercial operation of Unit Number 2 (250 MW) of the 2000 MW Subansiri Lower Hydroelectric Project through virtual mode on 23 December 2025, marking a landmark milestone in the project’s progress. The Subansiri Project stands as a symbol of India’s commitment to clean and sustainable energy, supporting North-East India’s growth, strengthening the national grid and advancing India’s ambitious net-zero goals. The momentous event was graced by Shri Pankaj Agarwal, Secretary (Power), Government of India; Shri Mohd. Afzal, Joint Secretary (Hydro), Ministry of Power, Government of India alongwith Shri Bhupender Gupta, CMD, NHPC; Shri Uttam Lal, Director (Personnel); Shri Sanjay Kumar Singh Director (Projects); Shri Suprakash Adhikari Director (Technical); Shri Mahesh Kumar Sharma, Director (Finance), and Shri Santosh Kumar, Chief Vigilance Officer.
Shri Pankaj Agarwal, Secretary (Power) lauded NHPC’s achievement, highlighting that the Subansiri Lower Project will greatly improve energy supply in the North-East and serve as a testament to India’s commitment to state-of-the-art, sustainable power systems. Shri Agarwal emphasised timely commissioning of the remaining units, noting that the Subansiri Project will continue to play a pivotal role in India’s transition to a net-zero energy future while generating substantial socio-economic benefits for local communities.
Shri Bhupender Gupta, CMD, NHPC, expressed his heartfelt gratitude to the Ministry of Power, Government of India, the Governments of Arunachal Pradesh and Assam, former NHPC leadership, the entire Subansiri Project team, all key stakeholders and partners for their dedicated support in making this milestone achievement possible. He further stated that the project will strengthen the national grid, support sustainable development in the North-East and provide reliable renewable energy to meet growing demand. Shri Rajendra Prasad, Executive Director, and Head of the Subansiri Lower Project, affirmed that the project team is fully committed to achieving commissioning of the remaining units of the project as per the stipulated schedule.
With the commissioning of Unit #2, the project is moving swiftly towards commissioning of 3 more units of 250 MW each shortly, followed by phased commissioning of the remaining four units during 2026-27. Upon full commissioning, the 2000 MW Subansiri Lower Hydroelectric Project will make a significant contribution to India’s renewable energy capacity, enhance national grid resilience and usher in a new era in massive clean energy contribution.
As India’s largest hydropower project, the Subansiri Lower Project comprises eight units of 250 MW each and is designed as a Run-of-the-River scheme with small pondage, diverting water through eight Head Race Tunnels (HRTs) to generate 7422 million units of renewable electricity annually contributing significantly to India’s green energy future. The project features the largest dam in North-East India, a 116-m high concrete gravity dam, which not only strengthens regional infrastructure and grid resilience but also enhances flood moderation and water management in the Subansiri River basin.
The Subansiri Lower H.E. Project is a showcase of engineering excellence and determination, housing India’s heaviest hydro generator rotors, largest stators and biggest main inlet valves. The project also features pioneering construction innovations, including the nation’s largest aggregate processing plants, the highest-capacity batching plant and the first-ever use of Rotec’s Tower Belt for dam concreting in India, underscoring NHPC’s commitment to technological advancement in large-scale hydropower development.
The Subansiri Lower H.E. Project is the first of the cascaded dams on the Subansiri River and plays a critical role in flood moderation. The project provides a dedicated 442 million m3 flood cushion for safer management during the monsoon season. With a gross reservoir storage of 1365 million m3 at Full Reservoir Level (FRL), the project ensures that approximately one-third of the reservoir remains empty during flood periods, enabling it to absorb excess floodwaters and protect downstream communities.
NHPC has implemented extensive riverbank protection and erosion control measures along the Subansiri River, completing works up to 30 km downstream and extending them up to 60 km. with an investment of about ?522 crore. This has effectively stabilised the riverbanks for over five years. In addition, NHPC is supporting downstream community development through livelihood programmes in piggery, sericulture and handloom, developed with IRMA. These initiatives, now in production, benefit around 5000 women farmers and promote sustainable socio-economic development in the region.
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