The law applicable to transboundary waters is a corpus juris that dates back to the 19th century. It originally focused on regulating the uses of transboundary watercourses for navigation and commercial transport. It was crafted primarily on the European and North American continents, and it has gradually become universally applicable, thereby taking a new shape. The regulation of transboundary waters was rooted in a strict dynamic of coexistence between sovereign entities: each acted as it saw fit with respect to “its” portion of the watercourse, which was treated at the same time as the image of the territory to which it is attached. The need for regulation only arose when uses affected the riparian states’ exercise of their “sovereign rights.” Since the 1990s, the law has tried to break away from this “classical” logic to make room for more community-based and even “ecosystem” notions based on aspects of joint management, and sometimes even pool of shared resources. A number of treaties have been negotiated and adopted by states bordering transboundary watercourses in Europe, Asia, Africa, and the Americas. They reflect, and sometimes even develop, some of the principles and rules enacted in broader forums, such as the United Nations (UN) or its Economic Commission for Europe, or the European Union. These efforts show the steps taken in the field of transboundary waters management, but they also reveal some of its limits, as they do not always comprehend all facets of water management and protection.
Rhett B. Larson
Increased water variability is one of the most pressing challenges presented by global climate change. A warmer atmosphere will hold more water and will result in more frequent and more intense El Niño events. Domestic and international water rights regimes must adapt to the more extreme drought and flood cycles resulting from these phenomena. Laws that allocate rights to water, both at the domestic level between water users and at the international level between nations sharing transboundary water sources, are frequently rigid governance systems ill-suited to adapt to a changing climate. Often, water laws allocate a fixed quantity of water for a certain type of use. At the domestic level, such rights may be considered legally protected private property rights or guaranteed human rights. At the international level, such water allocation regimes may also be dictated by human rights, as well as concerns for national sovereignty. These legal considerations may ossify water governance and inhibit water managers’ abilities to alter water allocations in response to changing water supplies. To respond to water variability arising from climate change, such laws must be reformed or reinterpreted to enhance their adaptive capacity. Such adaptation should consider both intra-generational equity and inter-generational equity. One potential approach to reinterpreting such water rights regimes is a stronger emphasis on the public trust doctrine. In many nations, water is a public trust resource, owned by the state and held in trust for the benefit of all citizens. Rights to water under this doctrine are merely usufructuary—a right to make a limited use of a specified quantity of water subject to governmental approval. The recognition and enforcement of the fiduciary obligation of water governance institutions to equitably manage the resource, and characterization of water rights as usufructuary, could introduce needed adaptive capacity into domestic water allocation laws. The public trust doctrine has been influential even at the international level, and that influence could be enhanced by recognizing a comparable fiduciary obligation for inter-jurisdictional institutions governing international transboundary waters. Legal reforms to facilitate water markets may also introduce greater adaptive capacity into otherwise rigid water allocation regimes. Water markets are frequently inefficient for several reasons, including lack of clarity in water rights, externalities inherent in a resource that ignores political boundaries, high transaction costs arising from differing economic and cultural valuations of water, and limited competition when water utilities are frequently natural monopolies. Legal reforms that clarify property rights in water, specify the minimum quantity, quality, and affordability of water to meet basic human needs and environmental flows, and mandate participatory and transparent water pricing and contracting could allow greater flexibility in water allocations through more efficient and equitable water markets.