In reply to:

I'm amazed you had this information at your fingertips to respond to this thread!
How so? I did notice, however, that both Devil's Lake and the midwestern lake mentioned once had outlets since filled-in from disuse.

as I mentioned, I once lived there, and my mother still gets the local paper, so my <ahem> natural interest is spring fed. [and specifically, a google of >"Devil's Lake" flooding< sufficed nicely]. and, as to the outlet, of course the lake will continue to rise until it finds its current natural outlet -- I think they've said it will take another meter, but that will flood more thousands of acres of farmland (and woe betide the town, as well).