Introduction

Protests are erupting in Arunachal Pradesh against India’s proposed 11,000 MW Siang Upper Multipurpose Project SUMP[1], a project pushed as if fait accompli to withstand the possible impacts of China’s 60,000 MW Medog Hydropower Dam System, World’s largest hydropower project.

China, aside from the curated media briefs and speeches from the July 2025 groundbreaking ceremony on the Tibetan Plateau, has shared no details of the project: no official information on location of the dams, their storage or discharge capacities, operational aims, etc.[2] Chinese media and even its scientists go on to laud the project in bombastic terms[3] while hinting perhaps they do not have the details either[4]. China hails this as advancing its “national security, ecological, energy, livelihood and international cooperation”[5] ambitions. In its media, the storage capacity of the largest dam is sometimes quoted 16 BCM, while India seems to have estimated it at 5.5 Billion Cubic Meters (BCM).