On 19 February 2013, a Permanent Court of Arbitration (PCA)-administered Court of Arbitration issued a Partial Award on the dispute between Pakistan and India regarding the use of the waters of the Kishenganga/Neelum, a tributary of the Indus system of rivers. This article examines the tribunal's decision, which was mainly limited to interpreting the 1960 Indus Water Treaty (IWT), and its contribution to international environmental law and the law of non-navigational uses of international watercourses. After briefly discussing the dispute's factual context and procedural history, the article critiques the tribunal's methodology, which was based on an inconsistent application of the principles of treaty interpretation. The Award's contribution is therefore mixed: despite its almost complete disregard for the principle of ‘equality of right’, it has contributed to clarifying the criteria for determining ‘existing uses’ of a watercourse and reaffirmed both the substantive obligation to refrain from causing transboundary harm and the procedural duty to carry out an Environmental Impact Assessment under international environmental law.