Focus area
Tietê River
A long river that crosses São Paulo, where volunteers have tracked water quality for more than 30 years.
South America
Brazil
Focus area
The Tietê in São Paulo: a long river with a stubborn pollution problem and a strong volunteer tradition.
Geography and context
Brazil's Tietê River rises near Salesópolis, east of São Paulo, flows through the city and then runs inland across São Paulo state for roughly 1,100 kilometers before joining the Paraná River. Its basin covers 265 municipalities, and 79 percent of it lies within the Atlantic Forest biome.
The river has been watched closely by citizens for decades. Since 1993, volunteer groups have monitored the Tietê and its tributaries through a program that later grew into Observando os Rios, a network now active across the Atlantic Forest states. Recent measurements show a river that is slowly changing, but still under heavy pressure.
Focus area
Opportunities we may explore
- Learn from Brazilian water, sanitation and river specialists, and from the volunteer groups already monitoring the Tietê.
- Explore simple, repeatable river monitoring and riverbank surveys that local teams can maintain.
- Look at ways to reduce litter and waste reaching tributaries, working with neighborhood groups and local organizations.
- Treat safe drinking-water access as its own program, led by qualified local specialists.
Organizations to explore
Organization to exploreWorks on this waterway
SOS Mata Atlântica Foundation
A Brazilian civil society foundation working on the Atlantic Forest and clean water. Its Observando os Rios program, which began in 1993 as Observando o Tietê, has volunteers monitor river quality each month, and its annual Tietê study tracks the river's pollution stretch. Its 2025 Tietê expedition was carried out with Unifesp, UFABC, CENA/USP and USCS, with support from Instituto Itaúsa.
Official website of SOS Mata Atlântica Foundation (external site)
Organization to exploreCountry-level expertise
Instituto Trata Brasil
A Brazilian civil society institute (OSCIP) founded in 2007 that works for universal sanitation, including sewage collection and treatment. Its website describes research, public awareness and an annual Ranking do Saneamento of Brazilian municipalities. Its relevance is at country level, and the pages we read do not mention the Tietê.
Organization to exploreCountry-level expertise
Instituto Limpa Brasil
A non-profit organization, founded in 2010, that mobilizes people for cleanups and proper waste disposal and is Brazil's representative of the Let's Do It movement behind World Cleanup Day. Its own site reports actions in more than 1,200 cities. Its relevance is at country level, and the pages we read do not mention the Tietê.
Know these waters?
If you live or work in Brazil, your knowledge matters more than ours. We would like to listen.
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