As one of Russia's northernmost rivers turned a bloodlike red last week, plenty of fingers were pointed at the nearby Norilsk Nickel factory. But the world's "largest producer of nickel and palladium" initially had only denials, going so far as to say that "the color of the [Daldykan River] today doesn't differ from its usual condition." Now, a changed tune: In a Monday press release the company stated that an internal investigation found that "abnormal heavy rain" on Sept. 5 caused what the BBC refers to as a "filtration dam" to overflow, sending "residual wash water" into the river.

The AP reports the dike that was crested was located outside a waste storage facility at its Nadezhdinskaya plant. "Short-term river color staining with iron salts presents no hazards for people and river fauna," the press release continues.

A Russian Greenpeace official isn't assuaged by that line, telling the AFP that while "there is a ministry of environment commission there" now, following up on alleged pollution wrought by Norilsk Nickel is challenging because of the remote location and the company's control of the Taymyr peninsula where the incident occurred.

The AP notes the area has struggled with environmental issues dating back to the construction of the first plant there roughly eight decades ago. Indeed, the New York Times last week called the company "by many measures one of the world’s most polluting enterprises," noting the sulfur dioxide generated by the plant has formed a dead zone equal to two Rhode Islands around it.

(This river turned blood-red in an hour.)

This article originally appeared on Newser: Now, an Explanation for Russia's Blood-Red River