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date: 22 March 2018

Cooperation over Transboundary Water Resources in International Law

This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Environmental Science. Please check back later for the full article.

Developments in environmental science play a sentinel role in the continuing evolution of international water law (IWL) as a discrete field of normativity. IWL in this context refers to the rules and principles recognized by the international community as applying to shared transboundary freshwater resources, and the shared understandings upon which such rules and principles are based. For example, in the early days of IWL’s formation (e.g., during the two decades that the International Law Commission spent codifying the field), one of the key contentious issues involved the identification and definition of the appropriate unit of drainage to be subjected to international rules—the transboundary “river,” “watercourse,” or “drainage basin.” As the hydrological unity (not to mention ecological unity) of the entire drainage basin became scientifically apparent and more generally understood, it has become clear that international law should employ and focus upon the broader “drainage basin” concept.

The key substantive principles of IWL, notably the principle of equitable and reasonable utilization and the duty to prevent significant transboundary harm, though universally accepted by states, are generally understood to be somewhat vague and lacking in clear normative content. Therefore, the related procedural rules of IWL become of central significance. For example, if equitable and reasonable utilization generally requires a basin state to consider the interests of other co-basin states, the requirements to notify of planned projects, to address concerns raised and, if necessary, to enter into consultations and negotiations with potentially affected states assume great importance. Of course, in the context of projects the procedure of environmental impact assessment, based on the latest assessment techniques developed by environmental science, plays a vital role. More generally, both key rules of IWL rely upon the effective compilation and sharing of relevant hydrological and environmental / ecological information, which requires the technical means for hydrological and environmental monitoring, for the processing of large amounts of complex data, and for the communication of such data and findings.

In more recent times, the almost universal commitment of basin states to the protection of ecosystems of transboundary watercourses have been made more meaningful by means of the development by the scientific community of related scientific concepts and methodologies concerning, for example, ecosystem services (and payment for such services) and minimum environmental / ecological flows. Each of these methodological approaches can serve to facilitate effective ecological protection, but can also permit broader and more sophisticated benefit-sharing arrangements, which would allow the equitable allocation of costs and benefits, both water-related and non-water-related, and thus true implementation of the cardinal principle of IWL, the principle of equitable and reasonable utilization. Indeed, one can in some measure credit the recent ecological focus of many IWL regimes on the wealth of practice developed by scientific advisory bodies established under related multilateral environmental agreements (MEAs), such as the Scientific and Technical Review Panel (STRP) established under the 1971 Ramsar Convention on Wetlands.