Residents of Mumbai began noticing a peculiar sight on August 11: roving stray dogs tinted a light shade of blue. No one knew what to make of these canines, which were spotted in the streets seemingly unharmed but otherwise bucking nature.

Concerned observers now have an answer, but it’s not a very reassuring one. According to The Guardian, the 11 Smurf-colored animals were the result of pollution run-off in the nearby Kasadi River. Industrial waste, including dyes, has been identified as coming from a nearby manufacturing plant. Although dogs are known to swim in the river, the blue dye was also found in the air. After complaints, the Maharashtra Pollution Control Board investigated and found the factory, Ducol Organics Pvt Ltd., was not adhering to regulatory guidelines for waste disposal. They shut off water to the facility and issued a notice of closure last Friday.

“There are a set of norms that every industry needs to follow,” MPCB regional officer Anil Mohekar told The Hindustan Times. “After our sub-regional officers confirmed media reports that dogs were indeed turning blue due to air and water pollution, we conducted a detailed survey at the plant … We will ensure that the plant does not function from Monday and the decision sets an example for other polluting industries, which may not be following pollution abatement measures.”

Animal services workers who retrieved five of the dogs were able to wash off the dye. They reported that no other health issues were detected.

[h/t The Guardian]