I'd vote for the fairly regular floods. Heck, I remember after Jeanne there wasn't much at all that was underwater. Shortly after the waters receded I caught what to this day I swear was a young wels in my friend's pond. I spent years trying to catch another one but I've only ever seen the one. It had the right fins, jaw, colors. Everything.
Anyway, I vote floods. lol
Could it have been a Madtom? I think Wels are more coldwater fish.