16-50 inches. Dark gray-green, olive or dark gray above, with a row of small, dark squared markings along the upper sides, alternating with a row on the lower sides and middle of the back; underside pale yellow with diffuse gray spotting that increases posteriorly. The keeled scales are in 23-27 rows.
Green water snakes prefer large, permanent bodies of water, especially in open country and around open cypress lakes and marshes. They give birth to 8-34 young.
The southern part of the state and the Red, Ouachita and Mississippi River valleys.