The Governador Ney Braga Hydroelectric Power Plant, better known as Segredo, is located in Rio Iguaçu, in the city of Mangueirinha, in the Southeast region of the state Paraná. It was the first one in Brazil in which the construction of the main civil works was totally handed over to medium-sized companies.
Opened in 1992, it is the second biggest Copel (Power Company of Paraná) power plant in nameplate capacity. The work was carried outby a consortium, with the first phase being the construction of three tunnels to reroute the river and the second phase the execution of the drying process and the main civil works. It was the first hydroelectric power plant in Brazil to have an environmental impact project.