With the high potential of hydroelectricity development, the Mekong Basin region faces a rapid, widespread development pressure in the decades to come. Cambodia, Lao PDR, and Vietnam are the main focus areas where more hydropower dam projects are to be built along the Mekong tributaries. Though such projects significantly contribute to regional and national economic growth, local riparian communities are the ones who bear the brunt of the environmental impacts they cause. Livelihoods of local communities heavily depend on water from rivers and other natural resources in the area a complex way but this complexity is often overlooked by the environmental and social impact assessments conducted for hydropower projects. The past projects in the region, and from around the world, give us a glimpse of the magnitude of short-term and long-term impacts on the livelihoods of riparian communities.