Volta, river, c.290 mi (470 km) long, formed in central Ghana, W Africa, by the confluence of the Black Volta (or Mouhon, c.840 mi/1,350 km long) and the White Volta (or Nakambe, c.450 mi/720 km long), both of which rise in Burkina Faso. The river flows generally south, through a large delta, to the Gulf of Guinea at Ada. The Volta River system drains c.150,000 sq mi (388,500 sq km). Lake Volta (c.3,275 sq mi/8,480 sq km), one of the world's largest artificial lakes, extends c.280 mi (450 km) upstream behind Akosombo Dam, SE Ghana, in the Ajena Gorge. The dam (370 ft/113 m high; completed 1965), the principal unit of the Volta Development Project, regulates the flow of the Volta River, stores water for irrigation, and generates hydroelectricity (750,000-kW capacity) that supports a large aluminum industry. Since the 1980s, droughts have at times reduced the water impounded by the dam and diminished the electricity that can be generated.