The Tietê River (Portuguese: Rio Tietê [tʃi.eˈte]) is a Brazilian river in the state of São Paulo. The first known use of the name Tietê was on a map published in 1748 by d’Anville. The name means "truthful river", or "truthful waters”, in Tupi. The Tietê River is a historically significant and economically important river, which stretches 450 kilometers and allows for navigation of barges carrying various goods. Pollution of the Tietê River began subtly in the 1920s, but it has worsened significantly over time. In September 2010, National Geographic identified the river as the most polluted in Brazil. Despite efforts to clean up the river, it still suffers from pollution and environmental degradation, and some species are threatened, or possibly extinct.
