Rio Tietê foam blankets Salto, Brazil
On 28 July 2026, the Rio Tietê in Salto, São Paulo, Brazil was covered by a thick white‑gray foam that stretched from Parque das Lavras to the town’s tourist waterfall. The local Defense Civil warned that gases emitted from the foam could be harmful to health. The phenomenon, also observed in May, is linked to high concentrations of pollutants during the drought season. The state's environmental agency, Cetesb, monitors the river continuously with inspections, water sampling and satellite imagery covering about 1,000 km. Foam formation is facilitated by increased flow and turbulence at the waterfalls, which cause residues in the water to create foam. Municipal authorities and environmental groups say the foam results from the discharge of untreated detergent, organic waste and other surfactants from the Greater São Paulo area. Reducing future occurrences depends on expanding universal sewage collection and treatment throughout the basin. Local resident Daniel Santos filmed the event with a drone, saying, “O rio está com muita espuma novamente. Na realidade, isso está ficando muito frequente, quase não para.” The municipality of Salto and SOS Mata Atlântica are participating in basin committees to seek solutions for improving the river’s water quality.
Entities: Companhia Ambiental do Estado de São Paulo (Cetesb) · Daniel Santos · Rio Tietê · SOS Mata Atlântica · Salto
Claims
What the coverage asserts, and how well corroborated each claim is across sources.
- [● 3 SOURCES] Defense Civil warned that gases emitted from the foam may be harmful to health. (multiple sources)
- [● 3 SOURCES] On 28 July 2026, the Rio Tietê in Salto, São Paulo, was covered by an extensive foam layer. (multiple sources)
- [● 3 SOURCES] Reducing the occurrence of foam depends on expanding universal sewage collection and treatment across the river basin. (multiple sources)
- [● 3 SOURCES] Foam formation is promoted by increased flow and turbulence at waterfalls that cause residues to create foam. (multiple sources)
- [● 3 SOURCES] The foam is caused by discharge of untreated detergent, organic waste and surfactants from the Greater São Paulo region into the river. (multiple sources)
- [● 3 SOURCES] Cetesb monitors the Rio Tietê continuously with inspections, water sampling, and satellite imagery over about 1,000 km. (multiple sources)
- [● 3 SOURCES] The foam extended from Parque das Lavras to the tourist waterfall in Salto. (multiple sources)
- [● 3 SOURCES] The phenomenon also occurred in May 2026 and is linked to high pollution concentration during drought. (multiple sources)