That river was given the name of Pelotas and after joining with Rio do Peixe was later called river Uruguay 100 Km from River Canoas, the most important one flowing in Santa Catarina, at the boundary with Rio Grande do Sul, which transforms in a true sea of fresh water with the construction of the hydroelectric: Itá, Machadinho Barra Grande, Pai-Querê, Iraí and Itapiranga. Its affluent, Rio Quaraí, serves as a boundary between Brazil and Uruguay and its largest tributary is River Negro, that starts in the city of Bage, in Rio Grande do Sul - Brazil, and it flows 100Km into the estuary of the Prata.

Due to the great extension of the rivers of the Prata Basin that presents a great variety of climatic conditions: tropical in the springs of River Paraguay; subtropical in Chaco Argentina/Paraguay, in the Argentinean northeast and in the southeast of the Brazilian states; temperate in the south of Argentina between the Rivers Paraná and Uruguay in the south of Brazil and in Uruguay; dry in the springs of the tributaries in Bolivia and in the northwest of Argentina. That climatic variety, the fertility of their soils, their mineral reserve, the hydroelectric potential of their great rivers and the structures of navigable rivers becoming a great area with immense economical potential.

River Paraguay

The program of the hidrovia Paraguay Paraná appeared with the need of improving the transportation system in the trade area with the creation of Mercosul. The objectives of this program: to improve the navigability conditions in this system: to reach a maximun use during the 24 hours of the 365 days of the year.