India’s largest hydropower project, the 2,000 MW Subansiri Lower Hydroelectric Project, located on the Arunachal Pradesh–Assam border, has begun its test run, marking a significant step toward commissioning. 

NHPC officials confirmed that the wet commissioning of the first 250 MW unit started on 24 October, 2025. The process involves testing the turbine with water flow to ensure operational readiness before electricity generation. Four of the project’s eight units are ready for similar tests, and power generation will commence once two units are synchronised. 

Initiated in 2005, the project faced a prolonged suspension from 2011 to 2019 due to environmental concerns in Assam. Work resumed after the Prime Minister’s Office intervened and NHPC implemented enhanced safety and mitigation measures. NHPC Chairman and Managing Director Bhupender Gupta hailed the achievement as a milestone in India’s pursuit of clean, self-reliant energy.