Nerodia sipedon pleuralis
Auburn, Alabama
This is the most frequently encountered aquatic snake in most parts of Alabama.
Source: R.H. Mount; "The Reptiles and Amphibians of Alabama"
University of Alabama Press, 1975.
For more information on this snake, see: http://www.flmnh.ufl.edu/herpetology/fl-guide/nerodiaspleuralis.htm