39. Hydropower development. The current conflict and negotiations over the proposed development of 12 hydropower projects on the mainstream Mekong River is the most important transboundary case to date and one that is testing as never before the arrangements for dialogue and resolution of shared resource use and management. Already, the PRC—one of six Mekong riparian countries—has dammed the upstream portion of the river with the first four projects in a planned cascade of up to eight storage hydropower schemes. This unilateral action and its potential environmental consequences have caused great concern among lower Mekong countries. With the Lao PDR pressing to proceed with mainstream development, the MRC member countries are faced with the most significant strategic decision ever made affecting the Mekong River.5 The proposed damming of the Mekong River would have negative effects on downstream water availability, and sediment and nutrient supply, potentially reducing the size and shape of the Mekong Delta. Impacts on agriculture and freshwater and marine fisheries would reduce the capacity of farmers and fishers in the Tonle Sap and delta region to adapt to the impacts of climate change.