This. Sorry if I gave the wrong impression. My pup is the problem. He's the pick of the litter, front of the pack, first to do, courageous, etc. He's extremely high drive, high energy, and dominant, boy doesn't have an off switch, Yet. He will not take a clue when the adult tells him you're out of bounds, which is the showing of teeth, snap/snarl, you know, perfectly reasonable. The adult dog, his name is Butters, finds his only escape is into the water. Butters is a good dog, he's a bit soft, the pup dominates him completely until Butters knocks the pup down and pins his head down under his chin. He doesn't use his teeth, just his body, but still, I think this isn't going well and worry he is going to injure the pup. FYI - These are both my dogs. They are kept separated by a gate in the house. They get separate outings, play, and training. I'm trying to eventually integrate them, for the past month that's been outside daily potty time, pup on leash, and some on leash walking in town and once a week some off leash play time. The off leash time together is the problem. The puppy has good recall so I can call him off...but he goes right back to clobbering Butters. I'm very aware of the potential same sex aggression, we're not there yet as we're still just dealing with a very hyperactive pup. So I don't know if my pup is ever going to settle down, and it may be a case of testing the waters once a month. Sad really, because one of reasons why we added a puppy was to give Butters someone to run and play with and if he could talk, I am sure he'd say we chose poorly

. I think I'll try to take them out with just the puppy on his 20' tracking lead, that way I'll have a little control over the intensity and give Butters his breathing room.
I greatly appreciate all the feedback. Sorry that it wasn't more clear in my initial post that my pup was dominating my 4yo.