Paraná

River in South America; length 4,500 km/2,800 mi. It is formed by the confluence of the Río Grande and Paranaiba, both of which rise in southeast Brazil; the Paraguay River joins it at Corrientes in Argentina. It then flows generally southwards into the Río de la Plata estuary; length 4,500 km/2,800 mi. The river's lower course is navigable for large vessels for 1,600 km/994 mi; its upper course is interrupted by numerous cataracts and rapids. It is used for hydroelectric power by Argentina, Brazil, and Paraguay. The Itaipu Dam, near the Brazilian border with Paraguay, is the largest hydroelectric plant in the world.

The dam has 18 700,000 kW generators and was constructed at a cost of US $25 billion. 40,000 families were relocated with the creation of a 1,350 sq km/520 sq mi reservoir. The construction of the dam also drowned the Guairá falls 190 km/118 mi upstream.