That's a copperrattlemoccasin. But while it really does look like a cottonmouth/water moccasin, it's just a northern water snake. They flare their heads and flatten their bodies when the feel threatened, which makes them look like a water moccasin, which probably results in many of them being killed for no reason.
That property is near water. A pond a 100 yds or so away . It wasn't really flattened out. Was as big around as my mid arm. Wasn't aggressive like a cotton mouth would usually be. Idk. It lives on. I don't care alot for snakes but if they aren't right near house I usually leave them alone.
when you mess with them, they can get aggressive. in your picture, you can see his head like flattened and triangulated. that is one of their defense mechanisms. makes them look scary, hahahaha. if he was 3 foot long, I would say he had to be very big around. we used to catch them when I was younger and they stink very bad. have a very musky smell. google banded water snake, I am sure you will see some pics that resemble yours. jesse