Integrated Water Resources Management (IWRM) combines land and water management through broad-based stakeholder participation to realize multiple co-benefits in watersheds. The potential for IWRM in transboundary watersheds throughout the world is highly significant, since approximately 40% of the world's population lives in river and lake basins that comprise two or more countries (UNWater 2008). Almost 50% of the Earth's land surface lies within such transboundary watersheds, which provide over 60% of global freshwater flow. These watersheds also represent large tracts of land with high biodiversity and forest cover. It has been estimated, however, that a third of the world's watersheds have lost more than 75% of their original forest cover and that 17 river basins have lost more than 95% (Revenga, et al. 1998). Competition with activities that lead to deforestation, mostly due to a need for increased food production, makes it imperative to sustainably manage such watersheds and the ecosystem services (ES) from them (including food and water).