Sekong, Sesan and Srepok (3S) Basin in the Lower Mekong

Supporting a population of around 3.4 million people, the Sekong, Sesan, and Srepok (3S) River basin is an important sub-catchment of the Lower Mekong and represents a microcosm of its challenges. Covering just 10% of the Mekong Basin, the 3S rivers provide almost a quarter of the Mekong’s total discharge and nearly 15% of the river’s suspended sediment — which, in turn, provides nutrients to the Tonle Sap Lake's inland fishery as well as Vietnam’s rice bowl, the Mekong Delta. The 3S has more than 65 hydropower dams, which impact river flow, sediment transport, and fish migration.