Can India Cut Off Pakistan’s Indus River Lifeline?

Critical Questions
by

David Michel

Published May 1, 2025

On April 22, 2025, armed militants emerged from the woods into a scenic meadow outside the mountain town of Pahalgam in India and opened fire on unsuspecting tourists, killing at least 28 people and wounding dozens. India blamed Pakistan for the massacre, subsequently linking the attackers to that country. In retaliation, Delhi suspended the Indus Waters Treaty (IWT), informing Islamabad it would hold the 65-year-old agreement “in abeyance . . . until Pakistan credibly and irrevocably abjures its support for cross-border terrorism.” Senior Indian officials vowed to ensure that “not even a drop of water goes to Pakistan.” Pakistan denied any role in the assault, warning it would consider any effort to interrupt the river’s flow as an act of war.

Q1: What is the Indus Waters Treaty, and why does it matter?

A1: The IWT governs water usage in the Indus River Basin. The frontier that partitioned British India in 1947, separating modern India and Pakistan at independence, also divided the two nations over water. The six main branches of the Indus River system run westward through India before crossing into Pakistan. The new international border sliced straight through these six tributaries and cut across the water infrastructure and canal networks constructed by the British to irrigate the region’s agriculture. Upstream, India asserted its sovereign right to develop the rivers running through its own territory however it saw fit. Downstream Pakistan, suddenly severed from vital water sources originating beyond its borders, feared that India’s water demands could deprive it of the Indus’s flows, jeopardizing its economy and food security. Years of simmering tensions drew in the World Bank to mediate the dispute, brokering the 1960 IWT. Then World Bank President Eugene Black believed the Indus accord had headed off water conflicts that otherwise could have driven India and Pakistan into war.

Often characterized as a “divorce settlement” more than a cooperative agreement, the IWT divides the Indus Basin physically, splitting custody of the six major tributaries. To Pakistan, it allots control of the three Western rivers, the Chenab, the Jhelum, and the Indus main stem (together amounting to about 80 percent of the Indus system’s average annual flow). India must let these rivers run freely through its territory except for specific restricted uses. India receives rights to the three Eastern rivers, the Beas, the Ravi, and the Sutlej. When the Eastern branches exit India, they become available to Pakistan.

Q2: How vulnerable is Pakistan?

A2: Pakistan depends critically on the Indus. Over three-quarters of the country’s annually available renewable water resources come from outside its borders, almost entirely from the Indus. Nine in every ten Pakistanis live within the Indus Basin. Major cities such as Karachi and Lahore rely upon the river—or on groundwater aquifers that the Indus helps replenish—for their drinking water. Agriculture claims 94 percent of water withdrawals in Pakistan. The sector constitutes the backbone of the economy, representing 22.9 percent of GDP, accounting for 24.4 percent of exports, providing livelihoods for two-thirds of the rural population, and employing 37.4 percent of the total labor force. The Indus system waters more than 90 percent of the nation’s crops. Similarly, Pakistan generates one-fifth of its electricity from hydropower. Every one of the country’s 21 hydroelectric plants is located in the Indus Basin.

Yet despite the river’s importance, Pakistan has scant capacity to manage against sustained shortfalls in water availability. All Pakistan’s Indus Basin reservoirs combined provide water storage equivalent to less than 10 percent of the river’s annual flows, far below storage capacities in other countries and regions worldwide.

Q3: Can India block the Indus River flows to Pakistan?

A3: No. In the near term, India does not possess the infrastructure necessary to prevent the Indus’s flows from reaching its neighbor. This is by design. The IWT strictly regulates the infrastructure India can install and the water it can withdraw or store on the rivers allocated to Pakistan. On average, some 182 cubic kilometers (km2) of water stream through the six Indus branches from India into Pakistan every year, over 170 km² coming from the Indus main stem, the Jhelum River, and the Chenab. The IWT allows India only 3.6 million acre feet of storage capacity (about 4.4 km²) on these three Western tributaries.

Plans to build the infrastructure system of dams, reservoirs, and canals that would be needed to withhold or divert significant Indus flows, as some Indian authorities have announced, would take years to realize. The IWT limits India to erecting so-called “run of the river” hydropower stations on the Western rivers. Such plants operate without large reservoirs, impounding only small water stores, if any, to compensate for short-term fluctuations in natural river flow. Thus, the hydropower developments currently underway on the Indus would only marginally increase India’s water storage capabilities to regulate downstream flow, with completion timelines stretching to 2032 or beyond. Designing, siting, and constructing new hydro dams free from the IWT’s constraints would take even longer, committing considerable sunk costs—and lots of poured concrete—that could be onerous to undo should improving relations with Pakistan warrant changing course. Even then, hydroelectric dams can only hold back rivers temporarily, since generating power necessarily requires releasing water through the turbines. Operating hydropower infrastructure to deliberately derail river flows to Pakistan—rather than for delivering economical and reliable electricity to Indian consumers—would risk proving a costly, clumsy, and unpopular tool at best.

Creating robust capacities enabling India to purposely disrupt flows to Pakistan over time would demand substantial infrastructure for large-scale water diversions out of the Indus River. India has, in fact, long harbored aspirations to establish a massive water transfer program connecting its northern and southern river basins. However, the colossal National River Linking Project faces daunting economic, environmental, and political obstacles, and none of the 30 planned engineering efforts involves the Indus system. Alternatively, India might dramatically expand programs for “managed aquifer recharge,” intentionally siphoning waters from the Indus to replenish its rapidly diminishing groundwater resources. But the particular characteristics of groundwater systems render the practical mechanics, environmental ramifications, and policy impacts of such efforts unclear, in part because significant flows from underground aquifers seep back into surface rivers.

Barring an immediate ability to leverage control of Indus flows against Pakistan, some authorities propose India could take steps such as flushing sediments from major dams, silting the river during the upcoming cropping season. Though prospectively damaging to Pakistani agriculture, this tactic would also impact Indian water users downstream. Unable for now to block water flows to Pakistan, India can, however, halt the flow of information. In some ways, this could be India’s most powerful current card. The IWT requires the parties to share a good deal of data on project development, river flows, and hydrological conditions. By suspending the treaty, India can also cease data sharing, depriving Pakistan of flood warnings, for example, prospectively hampering the nation’s water management and potentially imperiling Pakistani lives and livelihoods.

Q4: What ramifications could the Indus conflict have for wider regional security?

A4: Born in the bitter legacy of Partition, conflicts over the Indus’s waters intertwine with national security and territorial sovereignty. The three western rivers that the IWT allots to Pakistan flow through the contested Jammu and Kashmir. Pakistan and India have fought three wars and countless lesser skirmishes over control of this majority-Muslim former princely state, which is claimed by both countries and divided by a de facto “line-of-control”. The Pahalgam attack, perpetrated by the Resistance Front, a militant group opposing Indian rule in Kashmir, figures in a long line of cross-border violence. Several of these earlier clashes ensnared the Indus in the ensuing escalations. Terrorist groups such as Lashkar-e-Taiba, responsible for the 2008 Mumbai attacks, regularly threaten to bomb India’s dams. In 2009, former Pakistani President Asif Ali Zardari published an op-ed in the Washington Post warning that failure to resolve the Indus issue “could fuel the fires of discontent that lead to extremism.” India, in turn, weighed suspending the IWT following the 2001 assault on India’s Parliament, and again in 2016 after a previous attack in Kashmir, Prime Minister Narendra Modi declaring that “water and blood cannot flow together”.

Yet the current conflict augurs a combustible new dynamic. This is the first time that India has followed through on its threat. In the past, Pakistan frequently accused India of manipulating the Indus to Pakistan’s detriment, fearing, for example, that India would release water from its dams to aggravate downstream flooding, a charge that India denies. Now that India openly declares its intent to degrade Pakistan’s water security, future Pakistani perceptions of Indian malfeasance will be that much more incendiary. Pakistani social media is already ablaze with claims that India has triggered a flood on the Jhelum River. If India actively pursues a plan to disrupt Pakistan’s water supplies, Pakistan might feel compelled to strike at Indian infrastructure to demonstrate its reach and its resolve.

Delhi’s decision to suspend the IWT could become dangerously counterproductive. Indian security analysts recognize that worsening water stresses undermine Pakistani society and economy. This vulnerability renders the country susceptible to India’s water leverage. But ratcheting up the water pressure could equally risk further destabilizing an already volatile neighbor. By the same token, India historically has also had fraught water relations with Bangladesh and Nepal, countries that have often felt strong-armed by the larger power next door. Delhi’s demonstrated willingness to abandon an established water treaty may set alarm bells ringing in Dhaka and Kathmandu.

Finally, India’s upstream position on the Indus gives it the hydrological upper hand against Pakistan. But India lies downstream from an increasingly assertive China on both the Sutlej River and the Indus main stem, as well as on the Brahmaputra River, known in China as the Yarlung Tsangpo. The eight major transboundary rivers rising from the Tibetan Plateau make China the “hydro-hegemon” of Asia. Chinese initiatives to expand China’s upstream infrastructure on the Indus River and Brahmaputra River have sparked grave concerns in India. Yet China is not party to the IWT, and no international agreement governs water uses on the Brahmaputra River. As geopolitical competition across the region deepens, more than a few Indian observers fear that Delhi’s use of water against Islamabad risks licensing Beijing to adopt the same strategy against India. Ultimately, India’s use of the water weapon to cut Pakistan’s Indus lifeline could prove to be a double-edged sword.

David Michel is the senior fellow for water security with the Global Food and Water Security Program at the Center for Strategic and International Studies in Washington, D.C.

Critical Questions is produced by the Center for Strategic and International Studies (CSIS), a private, tax-exempt institution focusing on international public policy issues. Its research is nonpartisan and nonproprietary. CSIS does not take specific policy positions. Accordingly, all views, positions, and conclusions expressed in this publication should be understood to be solely those of the author(s).