The mine fatalities of Ontonagon County, Michigan, Part of the Lake Superior Mine District. The Lake Mines 3 districts are: -Portage Lake District -Keweenaw Point District -Ontonagon District From 1855 to 1975 it is estimated there have been 2,000 mine related deaths for Keweenaw county, at least 1,700 for Houghton, and 100 for Ontonagon. Ontonagon County is located along the south shore ...