The Nam Ngum Dam is a hydroelectric dam on the Nam Ngum river, a major tributary of the Mekong in Laos. It is the oldest dam in Laos, and its reservoir is the largest water body in the country. The dam is approx. 90 km north of Vientiane, the capital of Laos, within the Vientiane Capital Province.
Its reservoir covers 370 km2 (140 sq mi), and is the largest water body in Laos. The Nam Ngum catchment covers 8,460 km2 (3,266 sq mi), and is on track to becoming one of the most heavily dammed catchments in Laos, with six additional dams at various stages of planning and construction, and two water diversions.
The dam was a product of the Committee for Coordination on the Lower Mekong Basin, otherwise known as the Mekong Committee, the predecessor to today's Mekong River Commission. Its development trajectory was similar to many of the dams developed in northeastern Thailand during this time, part and parcel of US Government efforts to inject development into the Mekong Region, and dissuade impoverished countries from embracing communism. Nevertheless, the dam was constructed during a time of very significant political turmoil in Laos, which eventually resulted in the overthrow of the US-backed royalist government, and the coming to power of a communist government.