The damage to the most important river in the state of São Paulo, 1,150 kilometers long, began in the 1920s. turning into a garbage dump”, says Malu Ribeiro, coordinator of the Water Network at Fundação SOS Mata Atlântica. Since then, sewage, industrial waste and all kinds of rubbish have contributed to making Tietê one of the most disgusting in the world. Thankfully, the river is a living dead: after rotting, it is reborn as it moves away from the capital. :-F
CLEANING OPERATION
Treated sewage can help clean up the river
All domestic sewage, treated or not, at some point ends up in rivers. Since this cannot be changed, the Tietê depollution project led by Sabesp (a sanitation company in the state of São Paulo) wants to expand the sewage treatment network for the population living around the river. In 1990, only 24% of sewage in São Paulo was treated. In 2009, it was already 68%. During this period, the extension of the completely polluted river strip decreased by more than 200 kilometers
WASHING DIRTY CLOTHES
How the river that is born clean becomes filthy, dies and is reborn
RISING IN SALESOPOLIS
In this city in the interior of São Paulo, the water flows clean and transparent through stones, inside the Parque Nascentes do Rio Tietê environmental reserve. In the middle of Serra do Mar, the source is at an altitude of 1,027 meters. You can find fish, plants and various animals living in or around the river. Whoever is braver can even drink the water…
BIRITIBA MIRIM
In this stretch there are already traces of pollution, but most of it is still organic. The biggest damage here is done by pesticides and fertilizers thrown into the water by farmers in the region. They literally fertilize the water (especially when it contains phosphate) and make aquatic plants proliferate and compete with fish and other living things for oxygen.
MOGI DAS CRUZES
Here the house begins to fall: the river begins to receive domestic sewage from the cities in the region. Waste reaches the water without any treatment, a factor that most contributes to pollution. Imagine the discharge of the 362,000 residents of Mogi going straight into the river. Result: in this part, about 60 tons of sewage are dumped per day
GUARULHOS
In Greater São Paulo, there are 680 tons of sewage (measured in oxygen needed to consume pollution) daily. From here, it’s 100 kilometers of dead river: with the dirt, no fish or plants survive – only anaerobic bacteria remain. In this stretch, the river is also still. As its width and depth were reduced, the flow is 114,000 liters per second, little for a river of this size.
PIRAPORA DO BOM JESUS
In this stretch, there are white foams that are formed when detergent residues are shaken by the waterfalls. These falls help the river to regain life: they help to naturally stop pollution and to move and oxygenate the water, in a natural process called self-purification. In addition, new tributaries throw a bucket of cold, but clean, water on the Tietê
SHELLS
With more oxygen, fish, plants, algae and micro-organisms reappear. Before arriving here, the river still receives good quality water from tributaries such as the Sorocaba and Capivari rivers, making it look like a “normal” river again. Despite the remaining pollution, boats are already sailing here and even those who dare to swim in it
BEAUTIFUL BAR
By the time you get here, the Tietê has recovered from its dark past and turned into a beautiful river. The quality of the water is still not ideal, but with good treatment, it can even supply some cities. But nothing is perfect. From here to its mouth, on the Paraná River, in the Baixo Tietê basin, over another 600 kilometers of course, there is no systematic measurement of pollution, only sporadic controls
TIETHERMOMETER
Find out how the Water Quality Index (WQI) measures river pollution
DISSOLVED OXYGEN (DO)
The less oxygen, the more polluted
BIOCHEMICAL OXYGEN DEMAND (oxygen consumption by water)
The higher, the more polluted
HEATTOLERANT COLIFORMS (group of bacteria found in poop)
The higher, the more polluted
AMMONIAL NITROGEN (NH4)
Found in urine, domestic sewage and pesticides. The more there are, the more pollution
PHOSPHOR
Also found in sewage, in soaps (detergent, soap) and in pesticides. The more, the more polluted
TURBIDITY
Everything that is solid dirt, earth and sediments from siltation. The more, the more polluted
RESIDUE
Just like turbidity, they are from dirt dissolved in water. The more, the more polluted
TEMPERATURE AND PH
Isolated, they have no direct influence on pollution
READ MORE
– What are the most endangered rivers in the world?
– What is acid rain?