(CNN) The mystery behind the bright red color of a river in Siberia may have been solved.
Turns out the puzzling hue of the water of the Daldykan River, by the Arctic town of Norilsk, was caused by a discharge from a metallurgical plant in the area.
After denying blame for the contamination of the water, Norilsk Nickel, the world's largest nickel producer, said Monday that a dike at its Nadezhda plant overflowed, coloring the river blood red.
"On the 5th of September after abnormal heavy rain," Norilsk Nickel said, "the overflow of one of the dikes occurred, and water entered Daldykan River."
The company said the "short-term river color staining with iron salts" presents no hazards for the people and river fauna, and said it will work to avoid such incidents in the future.
Last week, alarmed residents shared online bizarre images of the river and contacted authorities.
Russia's Ministry of Natural Resources and Environment said it is investigating the incident but suspected the red color came from a discharge of "an unidentified chemical" from the plant.
Residents have seen similar surrealistic scenes before. There is a lot of mining near Norilsk, because the area has massive deposits of nickel, copper and palladium.
The region is also known for its heavy pollution.