In many aspects water is among the most ‘shared’ resources on Earth. Close to 50 per cent of the Earth’s land surface area is comprised of shared river and lake basins. Some 276 river basins cross the political boundaries of two or more countries, and about 40 per cent of the world’s population lives in river and lake basins that cross international borders.1 Globally, about 2 billion people depend on groundwater, which includes well over 300 transboundary aquifer systems. These facts represent the basic premise of the transboundary water management challenge facing the international community. Therefore, developing approaches that balance interdependencies of transboundary waters is a matter of high importance. The 2006 United Nations Development Programme (UNDP) Human Development Report2 acknowledges that “managing that interdependence is one of the great human development challenges facing the international community.” Even so, about two thirds of the transboundary rivers do not have any cooperative management framework. It is clear that much remains to be done.