Back in June, there was a massive accident at the Eagle gold mine in central Yukon, on traditional Na-Cho Nyak Dun territory — 4 million tonnes of cyanide-laced rock collapsed. Surrounding surface and groundwater soon had elevated cyanide levels, and dozens of fish died. Cleanup efforts are underway, but now, the storage ponds are nearly full of cyanide solution and are at risk of another cyanide spill. Niall McGee is the Globe’s mining reporter. He’s on the show to explain what we know about this accident, what happened with the mine’s owner, and why it’s so crucial that they figure out how to treat the cyanide soon.