This chapter outlines the significance and urgency of the current global water crisis and demonstrates that the existing international legal architecture for transboundary freshwater ecosystems requires significant improvement to meet current and predicted transboundary water challenges, resolve conflict and strengthen cooperation. The chapter sets out the three overarching objectives of the book. First, to understand the rising impact of regional approaches to international law on transboundary freshwater ecosystems. This includes identifying the contribution of the UNECE Water Convention and other relevant UNECE environmental instruments as a coherent legal regime. Second, to provide a more coherent understanding of the relationship between the UNECE environmental regime, international water law, international environmental law and general international law. This includes examining the contribution of the UNECE regime to cornerstone rules and principles of international water law and emerging or missing concepts such an ecosystem approach or public participation. Third, to understand how the UNECE regime adds to or interacts (on a normative and an institutional level) with river basin agreements, river basin commissions, European Union water law and national law. The introduction highlights the timely nature of the enquiry against the contemporary context and frames the book’s place against existing writing on this subject.

The latest Sustainable Development Goal (SDG) reporting exercise demonstrated the wide spectrum of arrangements and shortcomings for transboundary cooperation at the river basin level in the UNECE regime, from basins with comprehensive legal frameworks to basins with no agreement at all. Transboundary water cooperation works best when there is a basin-level agreement and these agreements should be more detailed than regional or global treaties but must incorporate these rules and principles. This chapter identifies how the UNECE water regime contributes to transboundary water cooperation at the basin level through the development of basin agreements, river basin organisations and less formal cooperative arrangements. It identifies how the UNECE has supported implementation and compliance with the UNECE regime and international law at basin and national level and the involvement of non-state actors. It examines a range of basin arrangements including those with no agreement, like the Western Bug, or basins with advanced frameworks like the Danube and Sava. It also analyses the value of the UNECE regime in basins already subject to EU environmental law – seeking to understand the specific contribution of the UNECE vis-à-vis the EU law and discusses why EU states have demonstrated interest in the UNECE regime.