Rio Tietê dead fish found in Salto after black water phenomenon

Dead fish were found in a stretch of the Tietê River near Salto, São Paulo, following a phenomenon known as ‘black water’. The dark coloration of the water was observed near the Ponte dos Pescadores.

The local government attributed the change in water color to the opening of dam floodgates in the São Paulo metropolitan region, specifically in Pirapora do Bom Jesus and Santana de Parnaíba. This process can displace accumulated mud, sludge, and sewage from the riverbed. However, Emae, the agency responsible for dam management, stated that the increased flow caused by recent rains—rather than specific floodgate operations—revolves organic matter accumulated on the river bottom, temporarily altering the water's color.

Cetesb technicians have collected samples to identify the pollutants present, with results expected within 30 days. This is the second significant incident in three months; in May, the river was covered in foam due to untreated product discharge and increased water flow.