That's key to overall water levels because Lake Superior feeds the rest of the Great Lakes. Beaches would be broader. But boaters would find access to marinas and docks severely limited. Industry's fears Commercial navigation on the Great Lakes would be crippled. With shallower waterways to contend with, freighters would have to carry lighter loads.
Commercial shippers complain about the same thing today.
If the Canadian model is correct, global warming could wreck the industry. A drop of 5 feet might make the industry uneconomic. Warm water and lack of spawning grounds might alter the nature of animal species in the lakes in ways that aren't fully understood, the assessment says. Invasive species, acclimated to warmer waters, might get a stronger hold. Such a drop in water levels could put political pressure on northern Illinois to alter its use of Lake Michigan water.