I'm pretty positive that was just some kind of non-venoumous water snake judging from the color pattern. Its a little hard for me to see in the picture but if you look at the head, copperheads and most venomous snakes have bumps behind their heads which hold venom sacks giving their heads a triangular look. I don't know, I guess I don't have kids and am not coming into contact with them everyday but I thinks its such a shame when people kill snakes like that.