The Subansiri Lower Dam is an under construction gravity dam on the Subansiri River in North Eastern India. It is located 2.3 km (1.4 mi) upstream of Subansiri River on Arunachal Pradesh. 

The dam is officially named Subansiri Lower Hydroelectric Project (SLHEP).

The project is being executed by NHPC Ltd.

90% of the total work of the Subansiri Lower Hydroelectric Project  has already been completed. 

Once completed, it will be the largest hydroelectric project in India. On completion, the Subansiri Lower Hydroelectric Project will generate approximately 7,500 million kilowatt-hours of power annually, in a 90%-dependable year.

NHPC Limited commenced construction work of Subansiri Lower Hydroelectric Project in January 2005 after obtaining forest clearance on October 12, 2004. However, due to agitations and protests by local stakeholders, the project construction work was stalled from December 2011 to October 2019. The project construction resumed from October 15, 2019, after the clearance by National Green Tribunal.

What is a gravity dam ?

• A gravity dam is a dam constructed from concrete or stone masonry and designed to hold back water by using only the weight of the material and its resistance against the foundation to oppose the horizontal pressure of water pushing against it.