Guwahati: Assam Pradesh Congress Committee president and Deputy Leader of the Opposition in the Lok Sabha, Gaurav Gogoi, has raised serious concerns over the potential downstream impact of the proposed Siang Upper Multipurpose Project (SUMP) in Arunachal Pradesh on the people, ecology and economy of Assam. 

In a letter to Union Jal Shakti Minister C.R. Patil, Gogoi emphasised that the Siang River forms an integral part of the Brahmaputra basin and sustains Assam’s agricultural economy, riverine ecosystems and the livelihoods of large numbers of people. Any major intervention in its flow regime, he argued, requires a thorough, independent assessment of the consequences for flood risks, water security, riverbank erosion and downstream communities, along with full transparency and formal consultation with Assam.

While acknowledging that the 11,200 MW project is being positioned as a strategic response to China’s proposed mega-dam on the Yarlung Tsangpo, Gogoi insisted that the interests of Assam’s downstream communities must receive equal consideration. “The project’s stated objectives of maintaining year-round flows and moderating floods cannot be treated as guaranteed outcomes, particularly in a region vulnerable to extreme rainfall, landslides and glacial lake outburst floods,” he stated.

Drawing on Assam’s experience with the Lower Subansiri Hydroelectric Project, the Congress leader highlighted long-standing concerns over sudden water releases, riverbank erosion, flooding and damage to downstream livelihoods. He also cited a 2025 study that documented concerns among communities regarding flooding, declining fisheries and agricultural losses. Although the study did not examine SUMP in its current form, Gogoi said it reinforced the need for a comprehensive downstream impact assessment.

In the letter, Gogoi sought clarification on whether the Assam government had been formally consulted on the project and called for the public disclosure of relevant project assessments and hydrological studies. His key demands include an independent downstream impact assessment covering Assam, prior consultation with affected communities and experts, and stronger coordination, with real-time data-sharing between Assam and Arunachal Pradesh, to improve flood monitoring and early-warning systems.

He urged the Centre not to take any irreversible decision on SUMP without these steps, stressing that the safety, livelihoods and environmental security of the people of Assam must not be compromised. The letter comes amid ongoing protests against the project in Arunachal Pradesh, where indigenous groups have voiced fears of displacement and ecological damage. Arunachal Pradesh Chief Minister Pema Khandu has stated that no final decision on construction has been taken and that public consultation and consent would be essential.

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