Itaipú Dam is a huge dam on the Upper Paraná River , on the border of Brazil and Paraguay . Completed in 1991, it is one of the largest power plants on Earth. With a generation capacity of 14 gigawatts, the Itaipú Dam provides Brazil with about 15 percent of its electric power and Paraguay with about 75 percent of its electric power. The American Society of Civil Engineers included the dam on its list of the Seven Wonders of the Modern World.
The Itaipú Dam is a gravity dam, meaning it relies on its own massive weight to block the flow of water. It is actually a group of four smaller dams that together create a vast reservoir (artificial lake) of blocked water. The main dam and a wing dam are made of concrete . A wing dam only partially blocks the flow of water. A third dam is an earthfill dam, and the fourth is a rockfill dam. Earthfill and rockfill dams are made of loose materials and rocks dug nearby and compacted. Altogether, the Itaipú Dam stretches 4.8 miles (7.7 kilometers) long and rises 643 feet (196 meters) high. Its reservoir holds 23.5 million acre-feet (29 billion cubic meters) of water.
Construction on the Itaipú Dam began in 1975 as a collaboration between Brazil and Paraguay. The project involved 40,000 workers.
