India’s largest hydropower project undergoes test run

GUWAHATI

One of the eight units of India’s largest hydropower project, which straddles the Arunachal Pradesh-Assam border, has begun undergoing a test run, signalling its commissioning soon.

Officials of the NHPC Limited said the wet commissioning of the first 250 megawatt unit of the 2,000 MW Subansiri Lower Hydroelectric Project was commenced on Friday (October 24, 2025).

“Wet commissioning is basically a test run of the turbine to check several parameters without generating electricity. The test run with water flow may take four to five days,” an NHPC spokesperson told The Hindu on Saturday (October 25).

The Subansiri Lower project has eight units of 250 MW each. “Four of these units are ready for test runs. The next step involves synchronisation of at least two units for the project to start generating power,” he said.

The Subansiri Lower project, located at Gerukamukh on the inter-State boundary, was launched in January 2005. Work on the project was suspended in 2011 following protests by anti-dam activists in Assam and concerns over downstream environmental impacts.

The work resumed in October 2019 after the Prime Minister’s Office pushed for its completion, and the NHPC adopted enhanced mitigation and safety measures.

NHPC Chairman and Managing Director Bhupender Gupta, who attended the wet commissioning event, stated that the achievement was a “shining testament” to the corporation’s engineering excellence. “It is more than just a project milestone; it reflects India’s steady march toward a cleaner, greener, and self-reliant energy future,” he said.