[bkar824]

You're way less than 2:1 here on the river, which is the bare minimum I think you can call here with. I think you're up against a set of 2's or 6's or even 7's. Not much else this guy can be holding other than a really intense attempt at salvaging a broken flush draw. I doubt that is the case though, because with such a benign river (from his point of view) there really isn't anything to try to represent by a bluff. I think you're beat, and the odds are terrible on the river to find out. Good place to curse a lot and muck.