Two vast American rivers in Colorado and New Mexico have been turned yellow because of potentially toxic wastewater from a gold mine.
More than 11 million litres of acid mine drainage was accidentally triggered by a team of Environmental Protection Agency workers last week and could lead to greater pollution in storm or flood seasons.
The contaminated drainage contains heavy metals like arsenic, mercury and lead that have settled into river sediments but threaten to be churned up and spread across the land when the waters rise.
There has been no immediate evidence of harm to humans, livestock or wildlife from the ongoing discharge from the King Gold Mine, according to officials.
But residents along the Animas River and San Jan River have been advised to avoid drinking or bathing in water drawn from wells in the area.