Interesting, but the rendesvous were held in June when the water is high. Also Brown's Hole is on the Green, not the Snake. The only really serious canyon stretches of the Snake are from Idaho Falls to Conant Valley, and from Alpine Wyoming to the mouth of
Hoback River. Both of those canyon stretches were heavily prospected back in the old days. Even the benches were mined. Lots of flour gold, but few nuggets. The canyon of the Green is covered by Flaming Gorge Reservoir, sadly.
Jim