There will be a lot of boaters at the Hot Springs campground. it's located right on the highway about 4 miles east of Garden Valley, along the SF Payette. There will be a large group of catarafters - mostly running the NF, but there's usually a bunch of kayakers in the same area.
Right now, the South Fork has more water than normal. Deadwood reservoir is releasing 1200cfs, plus about 500 or 600 from lowman. So the canyon and staircase are at great flows right now. I'm not sure how long that release will hold.