By that time, the area may have had some snowy winters and wet springs and the lakes are rising. Then you'd want the structures out. Also, changing lake levels are good for the environment, Donahue said. The biggest obstacle to installing sills or control structures is cost. Another 3-foot drop, for instance, would wreak havoc along the heavily developed shoreline of Lake St. Clair.
Historical records show the lakes fluctuate, rising and falling over a period of years.
Some scientists, however, predict that global warming will mean the steady decline of lake levels. Peter Sousounis, associate professor of meteorology at the University of Michigan, said forecast models predict the lakes will drop 3 feet during the next 100 years. George Ryan of the Lake Carriers Association in Cleveland said freighters are carrying about 5,000 tons less per trip this year compared with 1997, when lake levels were higher. Pete Matta, chairman of MBIA and owner of the Lake Fenton Marina, said he believes lake levels will rise again and dislikes the idea of tinkering with nature. But it would have to become really a necessity, and by that I mean the health and welfare of people are in danger.