sfaoldguy

Here's another cottonmouth encounter that has stuck in my head all my life:
When I was very young my family spent weekends and vacations at our cabin on the bank of the Susquehanna River, near Harrisburg PA. I was with my grandfather, he was opening up for the weekend. When he opened the door to the bunkhouse part there was a Cottonmouth between the inner and outer doors. That snake was very surprised! I remember vividly that large open mouth and the sound of the hiss. The snake first came TOWARDS US like it was attacking! It turned around quick and went under the inside door. My uncle went in and eventually found it next to the wood-stove we used for heat in the winter. Unfortunately he killed it, but I don't think you could hurt the Cottonmouth population around there.

I have a "cottonmouth in the water" story also, similar to yours.
When I was about 15 a friend and I were wade fishing in the Swatara Creek in PA, a little over waist-deep, somewhat muddy water. John saw a snake nearing him on the surface of the water and called my attention to it. As it got closer he said " Crap, Al! It's a cottonmouth!". I believed him, we were VERY familiar with the species. As the snake got closer to passing by John he reached out his rod tip and tapped it on the back. The snake's reaction was to submerge, leaving us no indication as to where the venomous snake had gone. I had to stop and think about what I should do, and call John a several-word name I can't type here. My hope was that the snake would naturally try to get away from the hit by swimming AWAY from us, and I don't scare easy, but I was a little nervous for a while. I bet if a stick brushed by my leg at that time my heart would have been racing. Fun times...