In a significant development from Guwahati, one of the eight units of India’s largest hydropower project, strategically located along the Arunachal Pradesh-Assam border, has successfully commenced its test run, indicating that full commissioning is just around the corner.
NHPC Limited officials confirmed that the ‘wet commissioning’ – a vital test run for the first 250-megawatt unit of the massive 2,000 MW Subansiri Lower Hydroelectric Project – began on Friday, October 24, 2025.
An NHPC spokesperson clarified on Saturday, October 25, that ‘wet commissioning’ involves meticulously testing the turbine with water flow to assess various operational parameters, all without actually generating electricity. This crucial phase is expected to last approximately four to five days.
The spokesperson further explained that the Subansiri Lower project comprises eight units, each capable of generating 250 MW. Currently, four of these units are primed for their individual test runs. The subsequent step, which will allow the project to begin producing power, involves the precise synchronization of at least two of these units.
Originally initiated in January 2005, the Subansiri Lower project, based at Gerukamukh on the border between Arunachal Pradesh and Assam, faced a significant setback. Construction was halted in 2011 due to widespread protests from anti-dam activists in Assam, who raised serious concerns about potential environmental repercussions downstream.
Construction finally recommenced in October 2019, thanks to a concerted push from the Prime Minister’s Office to ensure its completion. This restart was accompanied by the implementation of enhanced mitigation and safety measures by NHPC to address previous environmental and safety concerns.
Attending the momentous wet commissioning event, NHPC Chairman and Managing Director Bhupender Gupta hailed the achievement as a “shining testament” to the corporation’s exceptional engineering prowess. He emphasized that this is “more than just a project milestone; it clearly reflects India’s unwavering commitment to building a cleaner, greener, and energy-independent future.”