Fish are found dead in a stretch of the Tietê River in Salto after 'black water' phenomenon

Several fish were found dead in a stretch of the Tietê River, in Salto (SP), after the "black water" phenomenon. City residents recorded the sad scene in photos and videos.

Some of the fish were found dead near Fisherman's Bridge. According to the city hall, the change in water color occurs mainly due to the opening of dam gates in the Metropolitan Region of São Paulo, such as Pirapora do Bom Jesus and Santana de Parnaíba (SP).

The opening is carried out after periods of rain or to control the water level, which pushes a large amount of mud, silt and sewage accumulated at the bottom of the river.

Technicians from the Environmental Company of the State of São Paulo (Cetesb) were on site to collect material to carry out tests on these samples and identify which pollutants were present in the water during the week.

TV TEM questioned Cetesb to find out what was identified in the incident. The body responded that the responsibility for managing the dams lies with the Metropolitan Water and Energy Company (Emae).

The results of the samples collected should be ready within 30 days, informed Salto's environment secretary, José Antonio Luciano.

In a note, Emae explained that the color of the water is related to the conditions of the river itself and that it occurred after the heavy rains of the last few days.

"The phenomenon, which occurs especially after periods of drought and less precipitation, is intensified due to the fact that the Tietê River receives contributions from the entire São Paulo Metropolitan Region along its course, carrying this water downstream to the Salto region", he explained.

Also according to Emae, with the increase in flow and the strength of the water, part of the organic matter accumulated at the bottom of rivers and streams is disturbed and remains in suspension, "which can temporarily cause the water to become darker in color."

The company said that it works directly to control floods on the Tietê River, following technical protocols that aim to prevent accidents and inconvenience for the population.

The Municipality of Salto, through the Department of the Environment, reported that it was called and was on site after the episode of changing the color of the water.

"Given the presence of water with inadequate characteristics in the Tietê River, it is expected that fish will seek areas with better conditions, moving to the river's tributaries. However, these watercourses have limited capacity and do not simultaneously support a large concentration of fish, which can contribute to the occurrence of mortality", states the agency, in a note.

The Environment Secretariat also stated that it is monitoring the situation and taking the appropriate measures.