Banded water snake

Broad-banded Watersnake, Nerodia fasciata confluens

Inconclusive - not enough visible to make an ID.

My guess would be a species of Nerodia, not sure which. It just doesn't have the same proportions as a water moccasin. Hard to tell from the picture though, a head shot would help

from wikipedia: These crossbands, which usually have black edges, are sometimes broken along the dorsal midline to form a series of staggered half bands on either side of the body. These crossbands are visibly lighter in the center, almost matching the ground color, often contain irregular dark markings, and extend well down onto the ventral scales.