Acid drainage from the Tulsequah Chief Mine discolors a leaking containment pond next to the Tulsequah River in British Columbia in 2013. Developer Chieftain Metals is in receivership. (Photo courtesy Chris Miller/Trout Unlimited)

Acid drainage from the Tulsequah Chief Mine discolors a leaking containment pond next to the Tulsequah River in British Columbia in 2013. Developer Chieftain Metals is in receivership. (Photo courtesy Chris Miller/Trout Unlimited)