greatlakes mining co,Great Lakes Mining - Center for Biological DiversityGreat Lakes MININg. The Great Lakes region contains nearly 85 percent of North America's surface freshwater, and more than 20 percent of the world's supply of . Gogebic Taconite LLC (GTAC) is a Florida-based mining company aggressively promoting a four-mile-long open-pit iron-ore mine in the Penokee Range in.greatlakes mining co,Mining and Great Lakes Communities - Great Lakes and St .Jun 20, 2013 . Reserve Mining Company Discharged Directly to Lake. Superior at Silver Bay, MN. • Over 500 million metric tones of pulverized iron tailings dumped into. Lake Superior. • Tailings contained asbestos-like minerals that contaminated Duluth and Superior drinking water. • Landmark EPA case in 1970's.