I usually don’t get that close a look as they run away, usually straight into the water. (Cottonmouths around here.)

The patterns are so similar that it is kind of pointless to try and identify. All the damn different gopher snakes too.

Every freaking snake that isn’t a black snake, in Texas, seems to look like this.

Just treat them all as venomous, leave them alone, and go about your day.