The decline presents a long-term threat to carriers that rely on the Great Lakes system for transport. The American Waterways Operators, an advocacy group for the tugboat, towboat, and barge industry in Arlington, Va., said that every inch of water loss in the Great Lakes decreases the carrying capacity of a single barge by 17 tons of cargo. That means that the loss of a foot would cause a capacity loss of 204 tons per barge.
In a statement, the organization called the water loss “a severe, ongoing situation.”
Similarly, the Lake Carriers’ Association, an advocacy group representing 17 companies that use the Great Lakes for cargo transport, estimated that some 10,000 tons of cargo could not be transported in 2012. Charter boat and commercial fishing operators around the Great Lakes region also said they fear tourism dollars will decline during their busy summer and fall season.
Researchers blame excessive dredging, both by the Chicago River system, which diverts water to the South, and the St. Clair River, which diverts water to deepen navigational channels to Lake Erie, Lake Ontario, and eventually the Atlantic Ocean. The International Joint Commission, a Canadian-US organization that looks for solutions to waterway issues, said it will release a report next month that examines the effect of dredging, among other factors, on water levels in the Great Lakes.
David Allan, a professor in the School of Natural Resources and the Environment at the University of Michigan in Ann Arbor, says that, while the water drop is indeed historic, data shows that it follows a somewhat cyclical pattern. The current level, for instance, is just short of previous low points in the 1930s and '60s.