Thanks, folks! I'm getting ready to head up to another lake shore park today ... I tend to worry a bit more than I should, and it sounds like wading around in the water, and then getting back into the shoes with damp feet, isn't something to think twice about.
I "went clipless" about a month ago, so I'm still getting used to it. I don't have a rack or panniers, and those Keens might wind up being useful in the summer. But it's good to hear that other peoples' bike shoes have been fine, long term, even after getting wet.