Siang Dam Project Explained: Why India Needs This Mega Dam in Arunachal Pradesh?

The Siang Upper Multipurpose Project is a proposed 11,200-MW dam on the Siang River in Arunachal Pradesh. It aims to produce clean power, store water and reduce floods downstream. The project has also become a major strategic and social issue.

Siang Upper Multipurpose Project (SUMP) Overview

What Is the Siang Upper Multipurpose Project?

The Siang Upper Multipurpose Project is a proposed 11,200-MW mega hydropower and water storage project on the Siang River. It is designed to produce clean energy, regulate water flowing in from across the border and moderate floods downstream.

​​​​​​Location

The project spans the Siang and Upper Siang districts of Arunachal Pradesh in the Eastern Himalayas. Parong, Dite Dime and Uggeng are the possible dam sites.

Initial Proposal

The idea dates back to 2008, when the government planned to use the Siang’s hydropower through two separate projects. Stage-I was to generate 6,000 MW and Stage-II was to generate 3,750 MW.

Project Consolidation

Later, the two stages were merged into a single 11,200-MW multipurpose project. The National Hydroelectric Power Corporation (NHPC) has been proposed as the developer.

China’s Dam Concerns

The project gained urgency after China began its Medog hydropower project on the Yarlung Tsangpo in 2025. The Yarlung Tsangpo is the upper stretch of the same river system, so a large upstream dam raises worries in India about how much water is released and when.

What is the strategic importance of India’s Siang Dam Project?

China’s dam-building upstream can change how much water flows into India. A large reservoir on the Siang would give India its own way to manage the flow.

• Water security: Stored water can be used in the dry season, so India is less exposed to sudden changes upstream.
• Flood control: The reservoir can hold back extra water and ease floods in Assam.
• Basin resilience: It strengthens India’s ability to handle the Brahmaputra basin’s water challenges.

Key Features of the Siang Dam Project

Large storage

About 9.2 billion cubic metres of live storage is planned to even out river flows and absorb sudden upstream releases.

Pre-feasibility studies

Geological drilling, rock testing and seismic studies are being done to check whether the site is safe and workable before approvals.

Challenges in Siang Dam Project

1. Local opposition: Groups such as SIFF and Adi organisations oppose the surveys. They want proper talks through their traditional kebang councils and protection of ancestral land.
2. Earthquake risk: The area lies in Seismic Zone V, the highest-risk category. Experts point to dangers such as quakes, reservoir-induced seismicity, landslides and glacial lake outburst floods.