Well, unless that snake manages to get to shore anywhere, it should end up in the Chesapeake bay eventually, and the Atlantic Ocean finally. If I remember my geography correctly, that is.
I doubt it would survive the Conowingo Dam....
I am not sure if a snake can manage the fish ladders for the shad to get past the Conowingo Dam that stands athwart the Susquehanna River 8 miles from the head of the Chesapeake.