Qualla: Paraiba do Sul

Paraiba do Sul: Introduction

Thu, 16 Apr 2026 00:00:00 GMT

Photo credit Vladhillrj, CC BY-SA 3.0. The river does not give up its name until it meets another. Above the Paraibuna dam, in the interior of Sao Paulo state, it is called the Paraitinga. Only when the Paraitinga joins the Paraibuna does the combined flow become the Paraiba do Sul - the South Paraiba, to distinguish it from the other Paraiba River that runs through northeastern Brazil. From that moment on it is one river, 1,137 kilometers long, bending west to northeast across three states before emptying into the Atlantic near Campos dos Goytacazes. Along its course stand some of the most heavily industrialized cities in southeast Brazil. Embraer builds aircraft on its banks. Volkswagen and Ford make cars. Brazil's first steel plant was built on its water. The Baron of Maua's engineers laid train tracks beside it. And beneath all that, pushing past smokestacks and concrete, the river holds roughly 100 native fish species, 40 percent of them found nowhere else on Earth. It is at once the heart of industrial Brazil and a biological refuge trying to survive the industry it feeds.

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Image: Vladhillrj | CC BY-SA 3.0

Paraiba do Sul: Course and Valley

Thu, 16 Apr 2026 00:00:00 GMT

Photo credit Gledson Agra de Carvalho, CC BY-SA 4.0. The river rises in the high country of Sao Paulo state and flows through a long broad valley whose fertility was recognized early. The Paraiba Valley - the Vale do Paraiba - has been one of the most densely populated parts of Brazil for centuries. It runs between latitudes 20 deg...

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Image: Gledson Agra de Carvalho | CC BY-SA 4.0

Paraiba do Sul: Navigating What Little Can Be Navigated

Thu, 16 Apr 2026 00:00:00 GMT

Photo credit Alexandre Josh, CC BY-SA 4.0. A river this long should be a highway. The Paraiba do Sul is not. Only two segments can be navigated at present. The lower 90 kilometers between the mouth and Sao Fidelis see incipient navigation by small boats carrying mainly construction material toward Campos dos Goytacazes. T...

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Image: Alexandre Josh | CC BY-SA 4.0

Paraiba do Sul: Fish and What Pressures Them

Thu, 16 Apr 2026 00:00:00 GMT

Photo credit Monarema, CC BY-SA 4.0. Water temperatures in this river follow a southern Brazilian pattern of distinct seasonal variation rather than the relatively stable profile of rivers further north. In Lorena, Sao Paulo, one survey recorded water as warm as 26.6 degrees Celsius in summer and as cool as 15.2 deg...

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Image: Monarema | CC BY-SA 4.0

Paraiba do Sul: The Conservation Plan and What Remains at Risk

Thu, 16 Apr 2026 00:00:00 GMT

Photo credit Jean-Baptiste Debret, Public domain. Other threatened species add weight to the river's precarious status. The bivalves Diplodon dunkerianus, D. expansus, and D. fontaineanus struggle with reduced water quality and sediment changes. Hoge's side-necked turtle, Mesoclemmys hogei, is one of the most endangered turtles ...

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Image: Jean-Baptiste Debret | Public domain