you may have been seeing a banded water snake, we have a variety here in arkansas, that is orangy copper, and looks very close to the copperhead, i see them in the norfork sometimes, not to be confused, the copperhead will swim, but not indidgidous like a cotton mouth or a water mocasin, he just swims if he has to, if he has been driven in the water, or fell overboard or something----see attached vid. of banded water snake, igonre the goofy azz background music