Siang Upper Multipurpose Project: Why the Proposed Mega Dam Has Led to Protests in Arunachal Pradesh
The proposed Siang Upper Multipurpose Project (SUMP), a very large dam on the Siang river (the name of the Brahmaputra in Arunachal Pradesh), has led to protests by members of the Adi tribal community since October 2026.
The project is to be built by NHPC Ltd (earlier called the National Hydroelectric Power Corporation). Its proposed capacity is about 11,000 to 11,200 MW of electricity, with a reservoir that can store about 9 billion cubic metres of water.
On October 23, 2026, a bandh (a shutdown called by protesters) against the project turned violent in parts of East Siang district. Police later reported 69 arrests and four detentions across Upper Siang, Siang and East Siang districts, some under the Arunachal Pradesh Unlawful Activities (Prevention) Act, 2014.
Mobile internet was suspended in Upper Siang district from November 1, and central armed police forces were deployed in the valley.
Protesting groups such as the Siang Indigenous Farmers Forum rejected the State government's offer of talks around November 5. They want detained protesters released and security forces withdrawn before any dialogue.
The State government says the project is only at the Pre-Feasibility Report (PFR) stage, which is a first study, not an approval. It argues that the dam is needed to manage floods and dry-season shortages, and to protect India from the risks of China's giant dam being built upstream at Medog in Tibet.
Siang Upper Multipurpose Project (SUMP): India's Storage Dam on the Siang
The Siang Upper Multipurpose Project is a very large dam that India plans to build on the Siang river in Arunachal Pradesh. The Siang is what the Brahmaputra is called when it first enters India from Tibet. The project is meant to store huge amounts of water, produce electricity and act as a safety buffer against floods and sudden water releases from upstream. It is still at the study stage, and no final decision to build it has been taken.
The current protests are against even the pre-feasibility survey work for SUMP. Protesters fear that once studies begin, the dam will follow. The government's stand is that a study is not an approval, and that the project is a strategic answer to China's upstream dam.
Adi Tribe of Arunachal Pradesh
The Adi are one of the largest tribal communities of Arunachal Pradesh. They live mainly in the valleys of the Siang river and its tributaries, in districts such as East Siang, Upper Siang and Siang. They are a Scheduled Tribe and speak languages of the Tani group, which belong to the Tibeto-Burman family. For the Adi, the Siang (which they call Aane Siang, or "Mother Siang") is not just a river but a part of their identity, faith and farming life.
The protests are led by Adi villagers who fear losing their land, homes and the river that is central to their culture. Their demand is that no project should move ahead without the free consent of the affected villages. This links the dam debate to wider questions about tribal land rights and consultation.
India-China Transboundary River Cooperation: The Brahmaputra Data-Sharing Mechanism
The Brahmaputra starts in Tibet, where it is called the Yarlung Tsangpo, and then flows into India and Bangladesh. India and China have no water-sharing treaty for this river. Instead, they cooperate through MoUs (memoranda of understanding, which are not legally binding) under which China shares flood-season data, such as water levels and rainfall, from its stations in Tibet. This data helps India warn people in Arunachal Pradesh and Assam before floods.
The government's main argument for SUMP is China's Medog dam. A big storage reservoir on the Indian side could absorb sudden water releases from upstream and keep water available in the lean season. Protesters, however, argue that the risks of a mega dam in an earthquake-prone zone would fall on Adi villages.
- Siang = name of the Brahmaputra in Arunachal Pradesh; called Yarlung Tsangpo in Tibet and Jamuna in Bangladesh
- SUMP: about 11,000 to 11,200 MW; about 9 BCM storage; developer NHPC Ltd
- SUMP is at the Pre-Feasibility Report (PFR) stage; no construction decision yet
- Districts at the centre of protests: Upper Siang, Siang and East Siang
- October 23, 2026: protest bandh turned violent; 69 arrests and 4 detentions reported by police
- Law used against some protesters: Arunachal Pradesh Unlawful Activities (Prevention) Act, 2014
- China's Medog (Yarlung Tsangpo lower reaches) project: construction began 19 July 2025; about 60 GW; about 1.2 trillion yuan
- Main affected community: the Adi tribe; traditional village council called the Kebang