Indeed, the old trails that lead from Celebration Park up river to Swan Falls Dam have been closed to motorized vehicles for years and years. One can hike, ride horse, or even bicycle, but the sandy trails make riding a bike very difficult. I tried! If you don't mind to hike there are a couple cool things in the closed off part. Halverson Lakes (I'd call'em ponds, but whatever) and they are fed by a waterfall which can sometimes be seen in the spring. Another neat spot is the old hermit cabin. Somewhere I've read some historical information on the old hermit, but can't remember the story nowdays. Here's what the old hermits stone cabin looked like a few years ago when I hiked in.
Also, several miles upstream there is a rough rough 2 track road which leads down to the river. Which is where I saw this fellow. Imagine seeing a snake on the Snake River!
Anyway, awesome sights from atop the canyon rim above Swan Falls Dam. Looked like you guys had a fun ride.