How did the Indus Waters Treaty (1960) affect water distribution and relations between Pakistan and India?

Introduction

The Indus Waters Treaty, signed in Karachi on 19 September 1960 by Prime Minister Jawaharlal Nehru and President Ayub Khan and also signed by the World Bank, divided the six rivers of the Indus system between India and Pakistan. It is often called one of the most successful water-sharing agreements in the world because it survived several wars. At the same time it permanently reshaped Pakistan's irrigation system and has become a growing source of friction as India builds projects on the western rivers.

Background

Partition drew a border across the world's largest contiguous irrigation system. The headworks of key canals, such as Madhopur on the Ravi and Ferozepur on the Sutlej, fell in India, while the land they irrigated lay in Pakistan. On 1 April 1948 India stopped the flow into these canals, exposing Pakistan's vulnerability as a lower riparian. After years of tension, David Lilienthal's proposal and World Bank mediation from 1951 led to the treaty in 1960.

Main provisions

India received exclusive use of the eastern rivers — Ravi, Beas and Sutlej — with an average flow of about 33 million acre-feet (MAF). Pakistan received the western rivers — Indus, Jhelum and Chenab — with about 135 MAF. India may use the western rivers for limited purposes: domestic use, limited irrigation and run-of-river hydropower within strict design limits. A Permanent Indus Commission with a commissioner from each country meets regularly and exchanges data. Disputes move in stages from the Commission to a Neutral Expert (for technical "differences") and a Court of Arbitration (for legal "disputes").

Effects on water distribution

Because Pakistan lost the eastern rivers, it had to transfer water from the west to feed canals that once drew on the Ravi and Sutlej. Under the Indus Basin Project, financed by the Indus Basin Development Fund with contributions from India, the World Bank and friendly countries, Pakistan built Mangla Dam (1967) and Tarbela Dam (1976), five barrages, a siphon and eight inter-river link canals. These works created the backbone of today's irrigation system and added large hydropower capacity.

The loss had costs. The Ravi and Sutlej became seasonal, mostly dry channels in Pakistan, harming groundwater, ecology and riverside communities in Punjab. Pakistan also became dependent on a few large reservoirs that are steadily losing capacity to silt, while new storage has been slow to come.

Effects on relations

The treaty separated water from politics for decades. It survived the wars of 1965 and 1971 and the Kargil conflict, and the Commission continued to meet even when other contacts were frozen. This made it a rare example of functional cooperation between the two rivals.

Tension shifted to India's projects on the western rivers. Pakistan objected to the Salal dam (settled bilaterally in 1978), the Baglihar dam (a Neutral Expert decision in 2007 largely allowed it with changes), and the Kishanganga project, where the Court of Arbitration in 2013 allowed the diversion but required India to maintain a minimum flow downstream. Disputes over Kishanganga and Ratle led to parallel proceedings before a Neutral Expert and a Court of Arbitration from 2022.

In January 2023 India issued a notice seeking to modify the treaty. In April 2025, after the Pahalgam attack, India announced that it was holding the treaty "in abeyance". Pakistan rejected this, stating that the treaty has no provision for unilateral suspension and that any attempt to stop or divert its waters would be treated as an act of war. The Court of Arbitration subsequently held that India's unilateral step did not affect its competence to continue the proceedings. Water, kept outside the conflict for six decades, has thus moved to the centre of it.

Assessment

For Pakistan the treaty was a hard bargain: it gave up three rivers in exchange for legal certainty over the larger western rivers and international help to build replacement works. That certainty has been its main benefit. The weakness is that the treaty was designed for the technology and climate of 1960. It says little about groundwater, environmental flows, climate change or the cumulative effect of many Indian projects that can alter the timing of flows, especially in the sowing seasons.

Way forward

Pakistan should insist on the treaty's binding nature and use its legal mechanisms and the World Bank's role fully; build diplomatic support by framing the issue as one of international law and human security; invest urgently in storage, canal lining and efficient irrigation so that it uses its own share well; strengthen data and monitoring of flows; and, in the long term, be open to a supplementary arrangement on climate change and environmental flows — negotiated, not imposed.

Conclusion

The Indus Waters Treaty divided the rivers, rebuilt Pakistan's irrigation system and kept water out of war for over sixty years. Its survival is now under strain. For Pakistan, which depends on the Indus for most of its agriculture, defending the treaty abroad and managing water wisely at home are two sides of the same national-security priority.