In August the water is very low, but still requires a waist, to chest deep wade where the walls are sheer. The falls keeps everything nice, and cool even in 100˚ weather! There is a nice spot of dry flats just at the swimming pool below the falls.
The gorge is a beautiful, short fissure/pocket gorge with walls hundreds of feet high and a floor of only a few dozen yards at its widest. It if glacier fed, so the water is always nice and cold, about like ice cold lemonade! Go midweek.
This gorge is easy to find since it is just a few miles past Multnomah Falls on the old highway.