The Metropolitan Municipality of Lima is now investigating an unusual incident involving Lima’s river on Tuesday, when it turned pink. That night, the agency took samples and sent them to a lab for testing, as extreme-weather account Volcaholic posted on X, formerly known as Twitter.

Sedapal, Lima’s drinking water and sewer service, responded to the discoloration on its Facebook page, saying that the quality of the water was not affected. The company said that its water treatment plants were working normally, and the discoloration was downstream of Sedapal’s catchment gates, which did not pose a risk to the water supply. “We guarantee the quality and safety of drinking water supplied to the population of Lima and Callao,” the message read.

No definite reason has been identified for the river’s discoloration yet. Environmental technologist Maria Angelica Villasante explained that color changes could be attributed to pollutants emanating from nearby industrial plants.

On X, Volcaholic commented that Mario Casaretto, president of Emape, suspected that poison had perhaps been dumped into the river without caution. Experts have suggested water pollution attributable to companies exploiting the natural resources as another reason. Both Casaretto and Sedapal, however, assured the public that the quality of water to the residents was not affected by this change as it occurred below the intake points and did not affect the La Atarjea treatment plant.

Sedapal replied to questions on Facebook, saying that the company was closely monitoring the river’s condition, especially about the color of the water. They said, “The situation is being addressed with the seriousness it deserves, and the competent authorities are taking the necessary measures to mitigate any environmental impact.”

The National Water Authority of Peru has taken samples of the rivers and will present its findings to the concerned authorities and take necessary steps if any variations are found.