Well, I don't *think* the Greenville area has water mocassins, not sure - they say we don't have them in Charlotte, but we do.
Copperheads mainly seem to be a problem in early spring but they are not particularly deadly, the main problem with a copperhead bite is infection. I am in the woods a lot and when a dog gets bit, even one as small as a beagle, most people just give them benedryl and watch them. I think the rattlesnakes in the upstate prefer dry hot rocky areas, but I could be wrong there. I am in the woods all the time - I mainly would not want to swim in a homemade pond due to mud & muck, not snakes.
But a pond will attract toads and frogs and turtles and these will attract snakes. I love our black snakes, they are fast and handsome. Actually the nonpoisonous snakes are your friends and many will eat the poisonous ones.