Yeah I'm trying to turn those markings into copperhead but it's saying water snake to me. I'm no expert though by a long shot. You have a pond, lake or creek nearby?

edit to add: just saw OP's post #12 above. Since you do live on a lake, I think that may just be what it was. Either way, I can't stand any of 'em really. If I have any question I shoot first and ID later! Had to evict a black snake from the chicken coop this summer. I told him he had one pass and if he came back I'd kill 'im next time. So far he's believed me.