In 1970, the consortium formed by the companies IECO (from the United States of America) and ELC (from Italy) won the international competition for the realization of the viability studies and for the elaboration of the construction project. Work began in February 1971. On April 26, 1973, Brazil and Paraguay signed the Itaipu Treaty, the legal instrument for the hydroelectric exploitation of the Paraná River by the two countries. On May 17, 1974, the Itaipu Binacional entity was created to admnistrate the plant's construction. The works began in January of the following year.