Guwahati: The National Hydroelectric Power Corporation (NHPC) achieved a major milestone in India’s hydropower sector with the successful synchronization of the third unit (Unit-1 of 250 MW) of the 2,000 MW Subansiri Lower Hydroelectric Project (SLHEP).
With this addition, the project’s operational capacity has reached 750 MW out of the planned 2,000 MW, strengthening hydropower’s role in stabilizing the grid, supporting peak power demand, and integrating renewable energy into the national network.
The unit successfully completed its trial run on February 27, 2026, following the earlier commissioning of Unit-2 on December 23, 2025, and Unit-3 on February 1, 2026. Unit-4 is expected to be operational soon, with Units 5 to 8 scheduled for 2026–27.
Once fully operational, SLHEP is expected to generate approximately 7,421 million units of electricity annually, reducing carbon emissions by nearly 7 million tonnes each year and significantly contributing to India’s green energy transition.
SLHEP, under development since 2005, has been implemented with careful attention to environmental, social, and safety concerns. Situated at Gerukamukh, the 116-metre high dam forms a 33.5 sq km reservoir holding 1,365 million cubic metres of water.
No homesteads are submerged, and agricultural land affected is limited to 77 families across two villages, with all rehabilitation and resettlement measures being addressed under the Arunachal Pradesh policy.
The project has diverted 3,999.3 hectares of forest land, with compensatory afforestation covering over 8,000 hectares. Environmental safeguards include maintaining a minimum river flow of 240 cubic metres per second to protect downstream ecology, flood moderation during the monsoon, sediment management, and riverbank protection along 60 km downstream.
Advanced SCADA automation ensures continuous monitoring and operational efficiency from NHPC’s central control centre in Faridabad.
SLHEP has also contributed to local development, benefiting thousands of households in Assam’s Dhemaji and Lakhimpur districts through initiatives in agriculture, livestock, sericulture, handloom, education, healthcare, and skill development, with CSR spending exceeding Rs 155 crore.
The project’s power is shared equitably, providing free power to Arunachal Pradesh and Assam while supplying reliable clean energy to the North Eastern Region and 16 other states.
During construction, around 7,000 local workers were employed daily, with lasting economic and infrastructural benefits expected for the region.