Reconciling the Interests of Upstream and Downstream Riparian States in Transboundary Basins: The Potential Role of "Benefit-Sharing" in the Ecological Protection of Shared Water Resources Dr Owen McIntyre Faculty of Law University College Cork National University of Ireland E-mail: o.mcintyre@ucc.ie Tel. +353-87-2861055 Introduction Upstream and downstream riparian States have traditionally relied on different substantive rules of international water law to protect their respective interests. Upstream States have tended to favour the principle of equitable and reasonable utilization, which emphasizes a balancing of the interests of riparian States having regard to wide range of relevant factors, while downstream States commonly invoke the duty to prevent significant transboundary harm. However, while downstream States seek to rely on ecosystem services that they require to be safeguarded by upstream States, it is increasingly understood in the discourse of international water law that harm can flow in both directions in a watercourse, with downstream developments potentially giving rise to restrictions on future upstream water utilization options and thus impacting directly on the interests of upstream States. Sophisticated "benefit-sharing" arrangements which take account of the emerging conceptual methodologies for ecosystems protection inherent to the so-called "ecosystems approach" to transboundary water management, such as environmental flows, ecosystem services and eco-compensation, can play a major role in reconciling the divergent interests of upstream and downstream States, while promoting inter-State cooperation for improved protection of international watercourse ecosystems. Methods This presentation will commence with an examination of the nature and background of so-called "benefit-sharing" arrangements, typically involving some form of payments for benefits, or compensation for costs, associated with enhanced stewardship of a shared transboundary watercourse by an upstream State, before proceeding to explore the basis in international law for such arrangements. In so doing, it will note that "foreclosure" of water utilisation opportunities for upstream States can amount to harm for the purposes of the no-harm rule, so that benefit-sharing arrangements involving some form of compensation for upstream States which forgo water utilisation opportunities with a view to environmental or ecosystems protection would be entirely consistent with the principle articulated in Article 7 of the 1997 UN Watercourses Convention. The presentation will also outline the kind of practical arrangements required to facilitate benefit-sharing in an international basin. The presentation will then proceed to outline the emergence and evolution of international watercourse ecosystems protection obligations under international law, focusing particularly on the environmental flows (e-flows) concept, a methodological approach that incorporates environmental concerns into the process of allocating water rights among different users, the concept of ecosystems services, which provides a methodology for the economic and social valuation of natural ecosystems and can thus for the integration of the value of such benefits into benefit-sharing arrangements, and "eco-compensation" mechanisms, which provide systems of payment for ecosystem services. Each of these tools has the potential to play a significant role in identifying benefit-sharing arrangements intended to achieve ecosystems protection in transboundary basins. In exploring each of these approaches, the presentation will consider China, as an exemplar of a critically important upstream State, and the international watercourses it shares with its southern neighbours, as basins in which ecological improvements might be achieved through the adoption of benefit-sharing arrangements. Results and Discussion This presentation will argue that benefit-sharing arrangements offer a unique opportunity to reconcile the divergent interests of upstream and downstream riparian States by facilitating some form of compensation for upstream States that take measures to ensure the continued availability of vital ecosystem services for downstream States. There exists some experience in the practice of international water law of successful benefit-sharing arrangements, though to date such arrangements have tended to facilitate the development of watercourse infrastructure, particularly hydropower facilities. The emergence of ecosystems protection obligations in international water law, however, militates strongly for the employment of such arrangements in pursuit of ecological objectives. Conclusion International water law continues to evolve in terms of the objectives which it is intended to achieve and the interests it is designed to protect. In recent years ecological objectives and interests have emerged as central concerns but it is clear that innovative approaches will be required in order to reconcile the complex interests involved. Benefit-sharing arrangements have a role to play in this regard, especially in light of the development of new methodologies for determining the quantity and timing of flows required for the maintenance of riverine ecosystems, the nature of the services provided by watercourse ecosystems and the value of such services.