ISLAMABAD:
The Permanent Court of Arbitration (PCA) ruled in favour of Pakistan on issues of general interpretation of the Indus Waters Treaty, saying that India would let flow the waters of the Western rivers for Pakistan’s unrestricted use.
The Hague-based PCA issued a binding Award on the interpretation of the IWT on August 8, 2025, which was published on its website on Monday, in a case brought by Pakistan in 2016. The court says that awards of a court of arbitration and the decisions of a Neutral Expert are final and binding on both parties.
The PCA has also ruled that the specified exceptions for generation of hydro-electric plants must conform strictly to the requirements laid down in the IWT, rather than to what India might consider an “ideal” or “best practices” approach.
The dispute between Pakistan and India centred on India’s design of run-of-river hydroelectric plants on the Western rivers, which included Indus, Jhelum, Chenab. Pakistan argued violation of IWT provisions. India did not participate in the proceedings but was kept informed and invited to join at every stage.
The court reaffirmed its jurisdiction, despite India’s objections and its April 2025 unilateral decision to hold the IWT in abeyance. The court unanimously determined that it was properly constituted and was competent to resolve the disputes set forth in Pakistan’s request for arbitration.
The ruling provides a general interpretation of IWT provisions, particularly Article III and Annexure D, setting design restrictions on low-level outlets, gated spillways, turbine intakes, pondage, and freeboard to protect Pakistan’s downstream water rights.
“The general rule is that India shall ‘let flow’ the waters of the Western Rivers for Pakistan’s unrestricted use. There are certain specified exceptions to this rule, including in relation to the generation of hydro-electric power, but these exceptions must be strictly construed,” it said, according to a press release.
“The design and operation of run-of-river hydroelectric plants must hew strictly to the requirements in the Treaty [IWT], rather than to what India might consider an ‘ideal’ or ‘best practices’ approach,” the PCA Award stated.
The court prohibited low-level outlets of water in the Pakistani rivers. It also prohibited low-level outlets by India unless strictly necessary for sediment control or technical purposes and added that they must be minimal in size and at the highest possible level.
The court explained that low-level outlets applied to openings in the dam that are located partially or entirely below dead storage level, including orifice spillways, but does not apply to crest-gated spillways or intakes for the turbines.
The gated spillways, it continues, applies to spillways at the crest of the dam structure, stating that as a starting point, India must endeavour to design plants without gated spillways, such as by use of an un-gated spillway.
Furthermore, the PCA said, the pondage required for firm power was to be calculated based on the water accumulated over a seven-day period at the minimum mean discharge – a historically low flow rate – taking into account the daily and weekly downstream release requirements.
“Maximum pondage is no more than twice this amount, it said. “When designing a run-of-river plant, India is only entitled to freeboard – the vertical distance in the dam wall from the full supply level to the top of the damof a height necessary to address the safety of the dam as a whole from overtopping, with reference to internationally-recognised standards.”
For each of the components of dam design, The PCA recommended that the parties must cooperate from an early stage of planning by India for a new hydro-electric plant on the Western Rivers, such that India’s designs could be modified as necessary in light of valid concerns raised by Pakistan.
“Awards of a court of arbitration are final and binding on the Parties (India and Pakistan), and have a controlling legal effect on subsequent neutral experts, subsequent courts of arbitration, and the court that issued the Award,” the PCA ruled.
“Decisions of a neutral expert on matters within his or her competence are final and binding on the Parties and any court of arbitration, in respect of the particular matter (and plant) on which the decision is made,” it added.
Experts term the Award “a great success for Pakistan” as the international court of arbitration endorsed the claims of Pakistan that India could not hold the IWT in abeyance and reduce water flows into Pakistani rivers by building dams.
“Pakistan had challenged two issues against India in the International Court of Arbitration related to water flows in Pakistani rivers: One issue was that India could not reduce water flows into these rivers by building dams,” former Indus Water Commissioner Jamaat Ali Shah said.
“The second issue was Pakistan’s objection to the design and construction of the Ratle and Kishanganga dams being built by India,” he added. “Pakistan maintained in its stance that India must allow the flow of water into Pakistani rivers, according to the provisions of the Indus Water Treaty.”
Shah said that the court had given an award in favour of Pakistan on the first issue, requiring of India to continue the flow of water in accordance with the IWT. He said the court would issue its decision on the design and construction of the Rattle and Kishanganga dams after hearing the views of both sides.
According to Shah, India had objected to the jurisdiction of the court, but the court proceeded with the case and awarded a decision in favour of Pakistan. “The court has endorsed Pakistan’s claims,” the former water commissioner stated.
Speaking about holding IWT in abeyance, Shah called it “a dangerous move”. He added that even the World Bank had also rejected India’s stance, and no other country had endorsed the Delhi’s claims or supported the decision.
“India has held the treaty in abeyance; therefore, it is not sharing water data with Pakistan,” he said. He urged the Pakistani government to file a case in the International Court of Arbitration to challenge India’s reluctance to share water data.
“We need to de-link this issue from the treaty,” he suggested. Stressing that India had also cited changes in environmental conditions, he noted that Pakistan was also no exception, as it too faced the same challenges. “Pakistan and India should address environmental issues separately,” he said.
Referring to Pakistan’s recent stance on revising the treaty by engaging commissioners of both countries, Shah said: “Commissioners of both countries regulate the treaty; therefore, the government of Pakistan should work on revising the treaty,” he added.
Ahmer Bilal Soofi, a prominent lawyer and former law minister, told The Express Tribune that the International Court of Arbitration had endorsed Pakistan’s point of view, calling it a great success. He said that the endorsement had also strengthened Pakistan’s position in the international community.
The Award does not yet decide on the specific cases of Kishenganga and Ratle projects; which “will be addressed in later proceedings,” the court said. The Award stresses the IWT’s aim is to balance water use and avoid unilateral advantages, recognising Pakistan’s vulnerability as the downstream riparian.
