On 19 July 2025, in a clearing outside Nyingchi, in the part of Tibet that China governs as an autonomous region, Premier Li Qiang lined up the heads of some of the country’s biggest state owned enterprises and told them he was about to approve the project of the century. What he was launching was the Medog hydropower station. A chain of five dams spread across roughly 250 kilometres of the Yarlung Tsangpo river, at the spot where the river does something almost no other major river on Earth does, it swings back on itself around Namcha Barwa, a 7,782 metre peak, and drops nearly two kilometres in elevation over just fifty kilometres of the deepest gorge on the planet.
The project was formally approved in December 2024, after more than a decade of appearing in China’s five year plans. It’s designed as one continuous build, with commercial power expected only after 2033. When it’s done, it should generate around 300 billion kilowatt hours a year, close to three times what the Three Gorges Dam produces, on a budget that different sources estimate anywhere between $137 billion and $168 billion, depending on which numbers you believe.
Chinese state media has started calling it, with obvious admiration, the dam of all dams, critics, far less impressed, have begun calling it the dam of death. Officials say the electricity it eventually produces will be enough to power more than 300 million people. Nobody has ever built anything on this scale before, because until very recently, nobody thought it could be done safely.
Downstream, in the Upper Siang district of Arunachal Pradesh, the same river is known as the Siang, and here it does something much more ordinary. It feeds paddy fields, fish traps and the riverside villages of the Adi tribe, just as it has for far longer than either of the governments now arguing over it has existed. Nobody in Along or Boleng was in the room in Nyingchi. Nobody from these towns sits on any commission that oversees the Yarlung Tsangpo, and in most years, nobody here gets reliable advance warning of how much water is going to come down the valley next week. Trust has sunk so low that, in May 2025, villagers in the Siang valley burned a footbridge to stop survey teams from reaching a site for the barrage their own government wants to build to protect them. That’s the mood in this valley now, not just fear of what China might do, but a deep fatigue at always being the last to know, from either side.
Keep that second detail in mind. Because within about thirteen months of that groundbreaking ceremony, a court in The Hague will rule that India tried something very close to what it now fears China is planning, on a different river altogether, and will tell India, unanimously, that it cannot.
First, though, the dam that set all of this in motion. Medog sits at what Chinese planners call the Great Bend, where the Yarlung Tsangpo swings almost 180 degrees before turning south toward India. The location isn’t accidental, it’s the whole point. A river that has already dropped from the roof of the world loses roughly half its remaining vertical fall inside this one gorge. That’s precisely why hydro engineers have had their eyes on it since the 1980s, and also exactly why nobody tried to build here until now. The ground beneath is some of the most seismically restless on the planet, prone to landslides and extreme weather on top of the earthquake risk. It’s why engineers who have studied the middle reaches of the same river for over a decade still see the lower gorge as a categorically harder problem.
A widely cited study of dams siting across western China found that close to half the region’s hydropower sites lie in zones of high to very high seismic hazard, and Tibet offered a stark reminder of what that means in January 2025, when a 6.8 magnitude earthquake killed dozens not far from where construction is now under way. Beijing has not published an environmental impact assessment for the project. And it doesn’t need to reach for a foreign cautionary tale, its own history supplies one.
The Three Gorges Dam displaced 1.3 million people and remains, a quarter century on, a live source of anxiety inside China’s own engineering establishment about dam safety at scale. Whatever else Medog is, it is a bet, an enormous, one-way bet, made by a government that answers to no referendum, in a canyon where nobody downstream gets a vote on either.
The official argument for going ahead anyway is simple enough, and not unreasonable on its own terms, China wants to peak carbon emissions by 2030 and reach net zero by 2060, and the rivers of the Tibetan Plateau hold the biggest untapped hydropower reserve still left within its borders. But there’s an unofficial argument that runs a layer deeper. In Chinese political culture, the ability to master a river has long served as a stand‑in for the legitimacy of the state, long before hydropower even existed as a technology. The Yangtze flood of 1931 alone is estimated to have killed close to two million people, and that history has fed a lasting belief, stretching back centuries, that an untamed river is unfinished business for whoever is in charge.
Building the largest dam on Earth in Tibet is also, not coincidentally, a way of pushing roads, transmission lines and permanent settlements into a historically restive frontier- infrastructure as a statement of who actually rules here, a use of dams that has nothing to do with kilowatt-hours. Tibetan advocacy groups have made exactly this point, framing Medog less as clean energy and more as resource extraction imposed on a marginalised region, with consequences for local identity and the sacred status the river holds in Tibetan Buddhism that Beijing’s engineering briefings don’t mention.
India doesn’t need to imagine what all of this looks like in practice. It can watch it unfold, almost in real time, on a different river a thousand kilometres to the southeast. Since 2020, the Stimson Center’s Mekong Dam Monitor has been using satellite imagery to track China’s eleven dam cascade on the upper Mekong, and the pattern is now well established. During its own wet season, China holds back water to refill two massive reservoirs, Xiaowan and Nuozhadu, which together store roughly as much water as Chesapeake Bay. Then, through the dry season, it releases that water to generate power. Both halves of this cycle hit downstream countries as a shock. In 2020 alone, the Monitor recorded about 20 billion cubic metres of cumulative Chinese dam restriction at a time when Thailand, Laos, Cambodia and Vietnam were already grappling with record low flows.
At the Chiang Saen gauge in northern Thailand, dam restrictions in one recent year cut the river’s flow by close to 19 percent. Further downstream, near Stung Treng in Cambodia, researchers have measured the cumulative effect of the cascade as slicing wet season flow by as much as 17 percent in some months, while roughly doubling dry season flow in others. The Mekong is increasingly behaving less like a natural river and more like a tap with someone else’s hand on the valve. Nobody downstream voted for this arrangement, and nobody has real recourse against it.
China participates in the Mekong River Commission only as a dialogue partner, a status that comes with no seat, no vote and no binding obligations. That is precisely the level of accountability Beijing has ever been willing to accept. To be fair to the data, the picture isn’t purely one of malicious control. In years when China’s own stretch of the basin runs dry, the cascade simply has less water to hoard or release. The Monitor’s researchers found that 2023’s restrictions were the lowest they had recorded since tracking began, precisely because a poor wet season left China’s own reservoirs with little spare water to withhold.
The mechanism, in other words, isn’t a conspiracy; it’s simpler and more durable than that. Whoever controls the valve upstream will always optimise for their own reservoirs first, whether it’s a good year or a bad one, and everyone downstream simply lives with whatever is left over. In that sense, the Mekong is the pilot programme. The Brahmaputra is next, at a scale roughly six times larger.
What India really worries about with Medog isn’t the total amount of water in a typical year, that kind of average can be managed. The real danger lies in the swings. A five dam cascade gives whoever controls the gates the power to hold back water and then let it go in a surge, whether by accident, through mismanagement, or, in some future crisis, as strategy.
Arunachal Pradesh’s chief minister, Pema Khandu, has been unusually blunt for a sitting official talking about a country India isn’t at war with. He has called the dam a ticking water bomb and an existential threat, and said plainly, China cannot be trusted. No one knows what they might do. He’s also made a more specific claim that a sudden release could rip through the entire Siang belt, while a diversion could drop the river so low in winter that people might be able to walk across it.
Whether either of these scenarios is technically realistic remains an open question, one that neither government has answered transparently, which, in a way, is the whole point. Further downstream in Assam, where the Siang becomes the mighty Brahmaputra, the same uncertainty hangs over a floodplain that already sees some of the worst seasonal flooding in South Asia, even without a foreign hand on the tap.
India’s answer, so far, has been to try to get its own dam up first. The proposed Upper Siang project, sometimes called the Siang Upper Multipurpose Project, is designed for around 11,000 megawatts of capacity and roughly 9 billion cubic metres of live storage. Officially, it’s sold less as a power project and more as flood buffering and drought insurance. Modelling cited by Indian strategic analysts suggests that without it, a Chinese diversion during the dry season could cut flows at the India-Bangladesh border by 11 to 26 percent, with it, that drop narrows to roughly 6 to 12 percent. In other words, it’s meant as a hedge against unpredictability rather than a rival claim on the water, though not everyone downstream of it sees it that way, which is precisely why local villagers were burning bridges to keep survey teams out in the first place.
Zoom out further and the numbers become almost too large to hold in view. The Tibetan Plateau and the wider Hindu Kush Himalaya are sometimes called the Third Pole, because together they hold the largest reserve of ice outside the Arctic and Antarctic, feeding roughly ten of Asia’s major river systems on which something close to two billion people depend, directly or indirectly, for water. Almost none of those people, and precious few of the states that represent them, have anything like a seat at the table where decisions are made about how that water gets released.
That’s because, on the Brahmaputra, there really isn’t a table to sit at. Look at what exists elsewhere. India and Pakistan have the Indus Waters Treaty, signed in 1960, brokered by the World Bank, legally binding and backed by its own dispute resolution machinery. India and Bangladesh have a negotiated, time-bound treaty governing the Ganga. India and China have neither. What they do have is a hydrological data-sharing memorandum, first signed in 2002 and renewed in 2008, 2013 and 2018, along with an Expert Level Mechanism set up in 2006 for annual talks on cross-border rivers.
The MoU is not a treaty. It doesn’t commit China to anything about what it may build, it only obliges Beijing to share flood season readings from a handful of monitoring stations, for which India pays roughly one crore rupees a year. It has already failed once in practice, during the 2017 military standoff at Doklam, China stopped transmitting data for most of a year, citing damaged equipment, while, awkwardly, continuing to supply the same kind of data to Bangladesh free of charge throughout.
The most recent version of the MoU expired on 5 June 2025, six weeks before Li Qiang’s groundbreaking ceremony, and as of this writing has not been renewed. India’s response has reportedly been to speed up its own construction rather than push harder for a binding replacement, what one recent analysis in The Diplomat bluntly called a ‘dam for dam’ policy standing in for a diplomatic one.
There’s a reason neither government feels much urgency about fixing this, and it has surprisingly little to do with China or India specifically. International law on shared rivers has never fully settled the argument between two competing doctrines. One, sometimes called the Harmon Doctrine after the American attorney general who first articulated it in an 1895 dispute with Mexico, holds that a state may do as it likes with water inside its own territory, full stop. The other, equitable and reasonable utilisation, holds that a river’s benefits must be shared fairly among everyone it touches. Unsurprisingly, upstream states lean toward the first and downstream states toward the second, and the preference has almost nothing to do with which particular country holds it. China argues from the upstream position on the Brahmaputra, and, as the next instalment in this series will show in uncomfortable detail, India has argued from exactly that same position when it is the one upstream.
There is no global backstop to force the issue. The 1997 UN Watercourses Convention, the closest thing the world has to a general rulebook for shared rivers, has been ratified by neither China, nor India, nor Pakistan, the three states presiding over some of the most contested waters on the continent. What jurisprudence does exist tends to point the other way from where Beijing is currently standing.
In 2010 the International Court of Justice ruled, in a dispute between Argentina and Uruguay over pulp mills on a shared river, that a state sharing a watercourse owes its neighbour a procedural duty to notify and consult before authorising a project likely to affect it, a duty the Court found Uruguay had actually breached, even though its mills were separately cleared of causing measurable environmental harm. China is not a party to that case and is not legally bound by it, and it has offered India nothing resembling the consultation the Hague required of Uruguay.
So India does have a genuine grievance here, and a solid legal tradition to lean on while making it. But what India doesn’t have, and this is the harder truth this series is meant to tell, is clean hands from which to make that argument. Just over a year after Li Qiang’s groundbreaking, a Court of Arbitration in The Hague has issued a unanimous ruling on a dispute over the Indus Waters Treaty with Pakistan, and it has said that India was wrong to treat a binding water treaty as something it could suspend on its own. India has rejected the ruling.
This won’t be India’s first brush with a Hague tribunal on this river system. Back in 2013, a similar panel ruled on Pakistan’s objections to India’s Kishanganga hydroelectric project. While it allowed India’s project to go ahead largely as planned, it also ordered India to maintain a minimum flow of nine cubic metres per second for Pakistan’s benefit downstream, arguably the closest thing on record to an equitable and reasonable ruling being imposed on an upper riparian India, rather than on China.
Article 2 of this series takes up that record in full. The abeyance, the ruling, and the considerably less comfortable mirror it holds up.
None of this makes Khandu wrong to be worried, or Delhi wrong to go ahead with its own barrage. It only means the story isn’t as neat as the one everyone is most comfortable telling, China as the lone outlier, India as the reasonable, law abiding victim. The more accurate version, and ultimately the more useful one, is that Asia currently runs its rivers on a hierarchy of size rather than a rule of law, and every state inside that hierarchy, India very much included, reaches for whichever doctrine happens to suit the particular river it’s standing on that year.
As the Himalayan glaciers that feed the Yarlung Tsangpo, the Mekong, the Indus and many other mighty rivers in the continent keep retreating under a warming climate, the volumes at stake in this argument are only going to grow less predictable, not more, for every government pretending it has this under control.
Back in the Siang valley, none of that abstraction changes what a sudden flood wave, or a river shrunk to walking depth in winter, would actually do to a village with no embassy, no seat on any commission, and no vote in either Nyingchi or New Delhi. The village only has a floodplain, a harvest, and an upstream neighbour, in both directions, that owes it nothing on paper. The mountains themselves do not recognise the border running through them, the ice feeding the Yarlung Tsangpo and the ice feeding the Siang is the same ice, obeying the same physics, indifferent to which capital claims jurisdiction over which stretch of the water it eventually becomes. Until that changes, the Third Pole will keep being governed exactly the way it is being governed now, by whoever finishes pouring concrete first.
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Selected issues, clear explanations and thoughtful perspectives—delivered when we publish.
