Shipments of iron ore on the Great Lakes totaled 61.6 million tons in 2012, a slight improvement over 2011. The Lake Carriers' Association (LCA) said the increase, 245,000 tons, is equal to about four cargos in a 1,000-foot-long vessel operating at current drafts which are significantly reduced by the dredging crisis and falling water levels. If a vessel that size was able to load to depths available when the Lakes were at near record highs in 1997, it could carry that much c...