The remote Siberian river which ran blood-red after an industrial spill has suffered severe discoloration in the past, NASA satellite images have revealed.
“Landsat satellites have collected images of red discoloration in the waters around Norilsk on multiple dates, including July 2015, July 2014, August 2013, July 1998, and September 1997,” the organization wrote on their Earth Observer website.
The area “has also been cited as one of the world’s worst pollution hotspots,” NASA noted.
The Association for the Minority Peoples of the Taimyr activist group first reported that the water in the Krasnoyarsk region's Daldykan River had turned red on Sept. 7.
They blamed the change on the nearby Norilsk Nickel mining plant, who initially denied involvement.
The company later admitted that heavy rains had caused water to flood over a "filtration dam" at the plant and into the river.
"Despite the short-term discoloration of the water, this incident does not present a danger for people or fauna in the river," the company said in an official statement.
The river has since returned to its normal color, but environmental activists say that they are still assessing the situation.
The Norilsk Nickel mining company made a net profit of $1.3 billion in the first half of 2016, according to the company's website.