Três Marias is a Brazilian municipality located in the northwestern part of the state of Minas Gerais.
The city lies on the important federal highway BR-040, which links Belo Horizonte to Brasília.
Neighboring municipalities are: Buritizeiro, Lassance, (N), Felixlândia (S), Corinto (E) Morada Nova and São Gonçalo do Abaeté (W).
There are those who affirm, based on astronomy, that it is because of the three stars belonging to the constellation Orion, and that are permanently visible in this region.
This version talks of a couple who lived on the bank of the river who had triplets, a rare case even today.
The objectives were to control the flow of water of the river in the periodical floods and improve navigability; the use of hydroelectric power and the development of industry and irrigation.
Begun in 1957, this great project was finished in January 1961, almost a world record in this type of construction.
The lake, known as the "Sweet Sea of Minas", has 21 billion cubic ms of water, a surface area of 1,040 square kilometres (402 square miles) (8.7 times greater than Guanabara Bay), and provides water to 8 municipalities; one of the many islands formed in the lake is an ecological station; the Estação Ecologica de Pirapitinga.
The speed of construction was due to the commitment of President Juscelino Kubitschek, who also completed the bridge over the São Francisco river, the BR 040 highway, and the new federal capital.