There is a Podunk Lake a few miles southwest of Ann Arbor, Michigan.
Welcome to the Straight Dope, Tenorissimo. It’s considered courteous to provide a link to the column at issue, like so: Where is Podunk? - The Straight Dope
Here’s the Wiki article on Podunk. Interesting to see there’s both a Twain and a Disney connection: Podunk - Wikipedia
And all this time I was convinced that Podunk was in Arkansas!