looks more like an eastern water snake to me. they are not venomous, but can be pretty aggressive and will bite. primarily they eat small reptiles and amphibians.

They'll eat fish too.

Thanks elke and patrick.

It's a Northern Water Snake (Nerodia sipedon). They are harmless and nonvenomous. They will eat frogs but don't pose a threat to a healthy self-sustaining free-ranging wild frog population as a whole.

Thanks Wayne.
Would it eat all the frogs in my small backyard ponds? I might have to relocate it if it does. I really enjoy those frogs singing me to sleep at night. I hate to do that......but I don't think I could convince it to change to peanut butter and jelly.