How do you tell if a snake is poisonous when in the water?

Answer 1

well, if u c a bright color of a snake, yes it's poisonous

EDIT: no real good way to tell, there is only one venomous water snake in north America and that is the cottonmouth, or the water moccasin, or its scientific name is agkistrodon piscivorus. They are all the same snake. Now just because i say water snake doesn't mean its the only snake found in the water here, i have seen several eastern diamond backs crossing rivers, and have even seen a few in the ocean going to and from islands, near Apalachicola, Fl. Copperheads can also often be found near the waters edge and sometime in the water!

There is a non venomous snake the brown water snake ornerodia taxispilota that looks very similar to the water moccasin.