Subansiri Lower Hydropower Project Unit-2 Operational

On 23 December, 2025, through virtual mode, the commercial operation of Unit-2 (250 MW) of the run-of-the-river Subansiri Lower Hydroelectric Project located in Arunachal Pradesh was inaugurated.

• Union Minister for Power, Housing and Urban Affairs Shri Manohar Lal on 23 December, 2025, through virtual mode, inaugurated the commercial operation of Unit-2 (250 MW) of the 2000 MW (8×250 MW) Subansiri Lower Hydroelectric Project.
• As India’s largest hydropower project, the Subansiri Lower Project includes eight units of 250 MW each and is designed as a run-of-the-river scheme with a small pondage, which diverts water through eight head race tunnels (HRTs) to generate 7,422 million units (MU) of renewable power annually, making a significant contribution to India’s green energy future.
• In addition to supplying power to 16 beneficiary states across India, the Subansiri Lower H.E. project will provide free power to Arunachal Pradesh and Assam, while the North-East region will receive 1,000 MW of electricity from the project, significantly strengthening regional energy availability.
• This project includes the largest dam in North-East India, a 116-metre-high concrete gravity dam, which not only strengthens regional infrastructure and grid stability, but also enhances flood control and water management in the Subansiri river basin.

Subansiri Lower Project

• It is located at Gerukamukh on the Arunachal Pradesh–Assam border. On completion, it will be India’s largest hydroelectric plant.
• This project is being developed by the government-owned National Hydro Power Corporation (NHPC). Construction of the project has been underway since 2005.
• The project cost was met through a term loan provision with 70% equity and 30% debt financing. The Central Government is providing budgetary support as part of the equity component.
• With the commissioning of Unit # 2, the project is rapidly moving towards commissioning of three units of 250 MW each, followed by the phased commissioning of the remaining four units during the year 2026-27.
• When fully operational, the 2000 MW Subansiri Lower Hydroelectric Project will make a significant contribution to India’s renewable energy capacity, enhance national grid stability, and usher in a new era of large-scale clean energy contribution.
• The Subansiri Lower H.E. Project is an example of engineering excellence, featuring India’s heaviest hydro generator rotor, the largest stator and the largest main inlet valves, along with innovations such as the country’s largest aggregate processing plant, the highest capacity batching plant, and the first-time use of Rotec’s tower belt for dam concreting in India.
• As the first cascaded dam on the Subansiri river, it provides flood control with a flood cushion of 442 million cubic metres. With a total reservoir storage of 1,365 million cubic metres at FRL, nearly one-third of the capacity remains vacant during floods to absorb excess water and protect downstream communities.

Subansiri River:

• Subansiri, or the “Golden River”, is the largest tributary of the upper Brahmaputra River.
• The Brahmaputra River is a major river of Asia, originating from the Chemayungdung Glacier near Mansarovar Lake in Tibet (China), where it is called ‘Sangpo’.
• Flowing through Arunachal Pradesh (Dihang/Siang) and Assam in India, it is known as ‘Jamuna’ in Bangladesh, joins the Ganga to form the Sundarbans Delta and empties into the Bay of Bengal, making it the lifeline of North-East India, on which the world’s largest river island Majuli is located.
• Brahmaputra River length: approximately 2,900–3,969 kilometres (overall).
• Brahmaputra River tributaries: Lohit, Dibang, Manas, Subansiri, Kameng, Teesta etc.