Siang dam explained: Why Arunachal's 11,200 MW project faces protests

Tension has been rising in Arunachal Pradesh's Siang belt over the proposed Siang Upper Multipurpose Project (SUMP). Sections of the indigenous Adi community, youth leaders and riverbank residents oppose it, and a 12-hour shutdown on Friday, October 23, was followed by reports of vandalism and violence that went on late into the night.

Here is what the project is and why it has become so contested.

What is SUMP?

At 11,200 MW, SUMP is billed as India's largest hydropower project. Plans to harness the Siang and Subansiri rivers go back to 1982, when the Brahmaputra Board proposed three smaller projects.

In 2013, the Centre raised concerns about Chinese projects on the Yarlung Tsangpo, as the Siang is called in Tibet. In 2017, the proposed Siang Upper Stage-I and Stage-II projects were merged into what became SUMP. It gained further prominence after China approved a 60,000 MW hydropower project on the lower Yarlung Tsangpo in December 2024.

Where does it stand?

SUMP is at the pre-feasibility survey stage. In September, Chief Minister Pema Khandu said the project would not be rushed beyond the feasibility stage and that if experts found it unviable, it would not go ahead. He also promised a social impact assessment, an environmental assessment and a detailed project report, with wide consultation, if it moves forward.

The government's case

The state government says SUMP is needed to counter China's planned upstream dam and calls it a national security issue. Pasighat West MLA Ninog Ering told The Indian Express it was a national-interest project needed as a check against any deliberate release of water from upstream. He said affected residents would be looked after with compensation and rehabilitation, and condemned the recent vandalism in Pasighat while saying the government was ready to talk.

Why people oppose it

Residents say the project threatens them economically and socially, and touches deep cultural and emotional ties to ancestral land. Dubit Siram of Geku village, general secretary of the youth wing of the Siang Indigenous Farmers' Forum, said he doubted the survey would ever find the project unfeasible and wanted a written assurance that no dam would be built.

Himanshu Thakkar of the South Asia Network on Dams questioned the security argument, saying the basic dimensions of the Chinese project were not known and that India should seek details from Beijing. He said the project would not be possible without the local community's full cooperation.