how close were the other dogs approching bon? if they were acting all wiggily sorta then Bon is in the right and those others are in the wrong, I recently read that it is akin to a stranger running up to you and trying to take something that as far you you are concerned is yours, you would tell them to take a hike too lol but as this water thing is NOT his, let him know that YOU control who is allowed their and who is not. basicly dont say anything if he growls gentaly lead him away, if he tries to go back just let him know that he is welcome back when YOU say he is, lead him back if if he growls again jsut lead him away again, he should catch on pretty quick.