Itaipú Dam (ētĪˈpō) [key], hydroelectric dam on the Paraná River, on the Brazil-Paraguay border. Jointly constructed (1975–91) by Brazil and Paraguay, it is the second-largest hydroelectric dam in the world, exceeded only by the Three Gorges Dam. The dam is 4.8 mi (7.76 km) long and rises to a height of 643 ft (196 m). The power plant has a 20 generating units with a total production capacity of 14,000 MW. By the year 2000, the facility was generating some 94% of Paraguay's energy supply and about 20% of Brazil's. The Itaipú Reservoir, created by the dam, stretches nearly 100 mi (161 km) upstream; Guairá Falls is submerged by its waters.