A collective of 114 scientists, researchers and practitioners on Monday called for suspending all construction, surveys and pre-clearance activities related to the proposed Siang Upper Multipurpose Project in Arunachal Pradesh, citing its ecological, cultural, and socio-political risks.

The Siang river flows into Arunachal Pradesh from Tibet, and is the main tributary of the Brahmaputra. The river is the site of the proposed 11,000 MW Siang Upper Multipurpose Project, touted to be India’s largest dam.

Residents of the region have been opposing the project for several years. Members of the Adi tribe, who live in the Siang basin, claim that the project poses a threat to their lands and their way of life.

In a statement on Monday, the collective said that the resistance to the project by the communities in the region reflected “a grounded understanding of the ecological, cultural, and socio-political risks” that it entailed.

The statement noted that the Siang river, also known as ‘Ane’ or Mother Siang, was sacred and central to the cultural identity and livelihoods of the Adi tribe.

“Hydropower construction involving tunnelling, road blasting, and reservoir formation would disrupt the relationship the Adi people have with Ane Siang,” it said.

The collective said that in the past, displacement often led to long-term socio-economic disruption, and compensation mechanisms rarely accounted for non-monetary values such as land-based identity, ecological knowledge and customary rights.

The collective also said that the communities in the Siang Valley depended on over 250 species of wild plants and animals for subsistence, medicine and cultural practices.

“The region is also home to a unique, highly sophisticated system of terraced wet rice cultivation practiced by indigenous Adi communities,” the statement said. “The Upper Siang Dam would submerge many of these terraces and disrupt irrigation systems, causing permanent loss of both farmland and traditional knowledge.”

The collective noted that the site of the Siang Upper Multipurpose Project fell in Seismic Zone V, which the highest risk category for earthquakes as per the Bureau of Indian Standards.

“Building large dams in such zones increases risks of earthquake-triggered landslides, dam failure, and reservoir-triggered seismicity,” it said. “Climate change has also intensified the frequency of glacial lake outburst floods, cloudbursts, and slope failures in the region.”

The collective noted that the Siang river originated in the Tibet Autonomous Region of China, making it strategically significant.

“Upstream hydropower and water diversion projects by China on the Yarlung Tsangpo have raised concerns over sediment flow, seasonal discharge, and water availability,” it said, adding that large infrastructure projects like the Siang Upper Multipurpose Project were often framed as strategic counter-measures.

“However, these projects disproportionately burden the local communities in Arunachal Pradesh,” the collective said. “The imposition of such projects without broad-based consent undermines trust in governance and democratic institutions.”

The statement also said that the project contravened the 2006 Forest Rights Act, the 2002 Biological Diversity Act and several other international environmental and Indigenous rights agreements.

The statement urged the Centre and the Arunachal Pradesh government to ensure the full recognition of community forest and resource rights under the Forest Rights Act.

The project

The Siang Upper Multipurpose project was first proposed in 2017 by Niti Aayog, a public policy think-tank of the Union government.

The dam was meant to counter the threat posed by Chinese hydropower projects being developed on the Yarlung Tsangpo river upstream, according to an Indian inter-ministerial technical committee report of 2022, seen by Scroll.

The Brahmaputra or Siang is known as Yarlung Tsangpo in Tibet, where it originates.

Chief Minister Pema Khandu has defended the dam as a way to protect the Adi tribes from a massive 60,000 MW Chinese dam that is, however, yet to be built.

Khandu claimed that the Chinese government, which is not a signatory to the international water conventions, “intends to divert water from the multiple water reservoirs to be created under the project to dry regions of Tibet and elsewhere”, leading to a fall in the volume of water in the Siang.

The Siang Upper Multipurpose Project, he said, has been proposed by the Union government to maintain the natural flow of water in the river all year round and “flood modulation” in case of a drastic water release by China.

However, residents of the area are sceptical about the government’s claim and fearful of losing their ancestral land and way of life. In a statement, representatives of the villages had pointed out: “The Siang region’s land comprises loose sedimentary rocks and is situated in a [fragile] seismic zone, rendering the feasibility of dams invalid in any sense.”

The Siang Indigenous Farmers’ Forum, a collective of agriculturists from the Adi community that has been heading protests, estimates that 40 villages along the Siang river – in Siang and Upper Siang districts – would be affected because of the proposed dam.

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