The recent dam failure details are described here: Tailings Ponds are the Biggest Environmental Disaster You’ve Never Heard Of. The lead in to the story:
The scale is hard to imagine: gray sludge, several feet deep, gushing with the force of a fire hose through streams and forest—coating everything in its path with ashy gunk. What happened on Monday might have been one of North America’s worst environmental disasters in decades, yet the news barely made it past the Canadian border.
Last Monday, a dam holding waste from the Mount Polley gold and copper mine in the remote Cariboo region of British Columbia broke, spilling 2.6 billion gallons of potentially toxic liquid and 1.3 billion gallons of definitely toxic sludge out into pristine lakes and streams. That’s about 6,000 Olympic-sized swimming pools of water and waste containing things like arsenic, mercury, and sulphur. Those substances are now mixed into the water that 300 people rely on for tap, hundreds from First Nations tribes rely on for hunting and fishing, and many others rely on for the tourism business.
This article describes some of the consequences: Millions of Fraser River salmon head for waters of B.C. mine disaster