Skip Three Rivers.
Plenty of access up and down from the Three Rivers mouth, if you've got waders. Hatchery fish tend to stack there a bit.
I'm not sure if it's still around, but you used to be able to drop a dollar in the box at the property immediately downstream from there. Gives you a little extra area to fish, but it's a little hike.
Above there, I think the hatchery fish aren't as plentiful, but there's all kinds of access, especially if you turn east OFF 101 at Beaver. There's a deadline up there somewhere, but it's quite a ways up.
Good luck.