Took a look at it at high water
I ran the gunny gorge in late may, and we stopped for lunch there. It was running 400 cfs or so and it looked huge for the riverbed. The sieve is easily visible when hiking up the short section from the river. The entire river bed is clogged with huge boulders. From there down looked like some pretty hardcore boating way above my level, but with lines through to the confluence with the gunny. I have no idea what the rest of the run is like.