You might be right but I don't think so. A year or so ago I had the same concerns and as I recall my research resulted in calling the snakes diamondback water snakes. At any rate I think the chance of getting bitten would be slim to none. Saw this same snake on the other side of this tiny pre-sediment pond 20 minutes later stalking another frog. I tried to get close to get a picture of the capture but the snake would have nothing of it. Dove deep into the water and away it went. I could only get so close before because it had the frog locked in its mouth trying get to swallow it. I've never seen these snakes very big. This one under 3'.
Also the head does not look triangular when they are not swallowing something. I'll look more closely when I run across another one though. Thanks for the concern.