While it's true that much of CC's so called trivia has been shown to be a product of his own speculation/imagination (i.e., I think it's mostly BS) I'm going to have to disagree with you on this one. Technically, while Lake Erie does border Ohio, I do not think that it is considered to be "in" Ohio.
On the other hand, a quick google search led to this link:
http://ohiodnr.com/Portals/7/pubs/Open_File_Rpts/05_Natural_Lakes_in_Ohio_1991.pdf
According to this 1991 report, there are over 100 natural lakes in the state of Ohio. I suppose that it's possible that all of these natural lakes have "vanished" in the last 21 years, otherwise, once again, CC's trivia is just what I said it was; BS!