Are copperheads and water moccasins more elusive than water snakes?

I know often times people mistake water snakes for copperheads or water moccasins Is it true if you go looking around near a creek or stream or place in southeastern United States where semi-aquatic snakes would usually be that you'd be more likely to find a water snake than a copperheads (Agkistrodon contortrix) or a water moccasin (Agkistrodon piscivorus )? Also are copperheads semi-aquatic? If not then what snake would you most likely find if you searched in a copperheads habitat in southeastern United States?