On August 4, 2014, an earthen dam failed at the Mount Polley Mine in central British Columbia, Canada. The dam had been built to hold a tailings pond that contained water and waste materials from local gold and copper mining operations.



The tailings pond covered over 4 square kilometers and within a few days, millions of cubic meters of wastewater and slurry had flowed from the pond into neighboring Polley Lake, Hazeltine Creek, and Quesnel Lake.



These two Landsat images show the area of active mining and associated tailings pond. In both images, the dark areas indicate clear water. The suspended materials within the tailings pond (first image) are more reflective, so this water appears brighter. In the August 6 image, the waste materials from the tailings pond can be seen (blue, green, and silver) flowing down Hazeltine Creek and into the two nearby lakes.