Here is a rather pissy guy I came across the other day. The best I can figure he is a Diamond Back Water Snake. His diamonds are not terribly distinct, but he does not match any of the other water snakes. He flattens his head when threatened to make him seem more menacing. When he is raised up it starts to look Cobraesque. When he's down like this he looks like a viper.
Non-poisonous but a really nasty disposition.
The bucket he is in is about 10" deep and 12"-14" across. He totals about 3 1/2 feet.