Canadian firm Northern Dynasty Minerals, owner of the proposed copper, gold and molybdenum Pebble Mine in southwestern Alaska, has 90 days to outline how it would mitigate the “unavoidable adverse impacts” caused by mine discharges to the state's aquatic resources, the U.S. Army Corps of Engineers told the company in a letter made public on Aug. 24.
The area of potential impact includes 2,825 acres of wetlands, 132 acres of open waters and 129 miles of streams.