Look, I know when I park out on Sauvie Island at one of the "clothing optional" entry points, I'll see some stuff that I won't really want to see (like the porky pig like older gentlemen that wear shirts, hiking boots, but no pants). It's the sacrifice I make a few times a year so my anti social dog can get some swimming in away from crowded areas and some of my favorite spots are inaccessible from other areas due to high water.
Usually, I can avoid eye to schlong contact as we pass each other on the beach. So, no harm, no foul in the big picture, I guess.
Well, to the guy I came upon this weekend (heh, I'll even leave this here without editing for the rookie commenters) anally masturbating (standing up no less) behind what you thought was vegetative cover, I say big harm, big foul. Even if you were inside the clothing optional area (you weren't, there's a big fucking sign on the beach about 100 yards upstream from where I caught you), what makes you think this kind of behavior is okay out in public?