The southern watersnake averages 22 to 36 inches in length. Broad, dark crossbands are present on the back and are separated by areas of yellow. The back is black, brown or red-brown. A dark stripe is present from the eye to the angle of the mouth. The scales are keeled (ridged). The belly is yellow with black or brown squares or blotches.
The southern watersnake may be found in Alexander County in Illinois. This snake lives in cypress swamps, river sloughs, oxbow lakes and drainage ditches. The southern watersnake is aquatic and is active day and night. It may ﬂatten its body when disturbed and/or release large amounts of nasty-smelling musk from glands at the base of the tail. Mating season occurs in April and May. In late summer, the female gives birth to between eight and 50 young, the number depending on her size and age. This snake eats ﬁshes and amphibians.