‘It looks like a stream of blood.’ A river near Buenos Aires turns red, sparking fears of toxic leak

The banks of the Río de la Plata are dyed red at the mouth of the Sarandi stream, whose waters are stained by unknown contaminants, on the outskirts of Buenos Aires, Argentina, Thursday, Feb. 6, 2025. (AP Photo/Rodrigo Abd)

BUENOS AIRES — A stream winding through a populous area on the outskirts of Buenos Aires has turned crimson red in recent hours, sparking fears of industrial chemical dumping, images shared by residents on social media showed Friday.

The Sarandí stream, near Villa Inflamable, in the municipality of Avellaneda, is home to tanneries and other industries that transform animal skins into leather using chemicals. Images of the blood-red waterway captured by residents quickly spread on social media, evoking apocalyptic imagery.

María Ducomls, a local resident, described waking early one recent morning to powerful odors.

“At 5:30 a.m., we already had a special and hazardous waste incinerator spewing pollutants into the air,” she told The Associated Press. Shortly after, she noticed the stream, “It looks like a stream of blood; we have never seen it like this,” she said.

Officials from the municipality of Avellaneda, about 15 kilometers (9 miles) south of the Argentine capital, suspect the presence of aniline, a toxic substance used in dyes and medicines.

Following the collection of water samples, they filed a complaint with the Buenos Aires province ministry of infrastructure and public services, which will lead an investigation.

Residents report that the stream has exhibited various unusual colors in the past — gray, green, violet, blue and brown — often with an oily surface. They say they have been filing complaints against local businesses since the 1990s, with several cases of alleged environmental contamination still open.