If you get some detailed bathymetric maps of Lake Michigan, and concentrate on the eastern shore (prevailing winds are from the WSW, and about 80% of the power in the wind will come from the western quadrant), you will find that the lakes gets quite deep very fast. It is only in the very northern part that the waters get reasonably shallow,  on the eastern shore. There is a lot of shallow lake on the western shore, but that is where the winds are least intense. The lake itself is lined up in a north-south direction, so it is the eastern shore (the Michigan side) where the most energy can be extracted.

But the really windy lake is Lake Superior, which gets very deep very fast, especially along the Michigan shore.

There was a recent study done by the state of Michigan of their offshore potential, which they listed as 322 GW (no depth limitations), 103 GW (60 m limit), or 55 GW (30 m limit). See http://www.landpolicy.msu.edu/modules.php?name=Documents&op=viewlive&sp_id=812.

Anyway, that's a lot of potential, and more than enough to power up a state that on average uses about 12 GW of electricity

Nb41