They are called northern waters snakes because they live near water and sometimes these reptiles are underwater.
This serpent was photographed on Des Plaines, Illinois' Big Bend Lake--on the west end, which I like to call Snake Shore.
Northern water snakes are often mistaken for poisonous water moccasins--but they are not native to northern Illinois.
Water snakes eat fish, amphibians and small rodents. While not poisonous, these reptiles are mean and they'll bite people. Give them space.
(Photo) Northern water snake