The Dongjiang River is one of the main tributaries of the Pearl River system in southern China. It is the primary water source for more than 40 million people, including the city of Hong Kong, which is located outside of the basin but receives about 80% of its municipal water supply from Dongjiang. Since the late 1950s, demands on the have Dongjiang increased as dams were constructed for flood control and hydropower. At present, water allocation among the cities and water quality are some of the region’s top concerns.