India’s monumental Subansiri Lower Hydroelectric Project, the country’s largest hydropower initiative spanning the Arunachal Pradesh-Assam border, has initiated test runs for its first unit, marking a significant step toward full commissioning. The 2,000 MW project, developed by NHPC Limited, commenced wet commissioning of its initial 250 MW unit on October 24, 2025.

According to an NHPC spokesperson, wet commissioning involves testing turbine parameters without electricity generation, with water flow tests expected to last four to five days. Four of the project’s eight 250 MW units are now prepared for testing, with power generation to begin after synchronizing at least two units.

The project’s journey has been marked by challenges, including a suspension from 2011 to 2019 due to environmental concerns and protests. Work resumed after intervention from the Prime Minister’s Office and implementation of enhanced safety measures by NHPC.

NHPC Chairman Bhupender Gupta celebrated the milestone as a demonstration of engineering excellence and India’s progress toward sustainable energy independence. Located at Gerukamukh, the project represents a crucial component of India’s renewable energy infrastructure, originally launched in 2005 and now approaching operational status after two decades of development.