The recent rains and snow runoff have raised many of these streams. This causes many of the minnows and nymphs in the riffles to become exposed to the strong currents thus washing them out from below the streambottom stones.The trout get a good shot at both the minnows and nymphs and feed heavily upon them.
An exceptionally effective technique is to fish a streamer which matches the minnows the trout feed upon on a 9ft 3X Classic Leader. Then attach an artificial nymph that matches the natural nymphs to a 24 inch 4X mono below it.
The rig I like to fish in the riffles and just below it is a Shenandoah Silver Ghost Streamer size 10 with a Murray's Dark Stonefly Nymph size 12 below it. I cast this across stream and allow it to sink deeply then strip it back 6 inches every 10 seconds in order to swim it right along the streambottom. This particular fly combination effectively matches both the minnows and nymphs from the riffles downstream about 100 feet.
As I wade and fish my way further downstream I find that by changing my two-fly rig combination in order to match the natural minnows and nymphs in that area helps me catch more large trout. The Shenandoah Skunk Streamer size 10 with a Murray's Caddis Larva size 14 on a 24 inch 4X dropper below it is very effective. Casting this rig across stream so it lands in each of the eddies along the far bank often brings a strike as soon as the caddis larva reaches the streambottom because many of these naturals live there. I once estimated one of these eddies the size of a card table held over 300 natural caddis larva.
Passage Creek and the Hidden Valley of the Jackson has this action. These streams are full but fishable.