Don't match the hatch
The Clinch Mountain streams are at perfect flows right now after coming down from last week's rain and snow. Water is clear with a little green tint as is often the case in the springtime when things start blooming.
There was a moderate hatch yesterday of size 16-18 Quill Gordons, but no trout were rising. The reason is simple - there was far more food available and active beneath the surface. With water temps still in the lower forties, and so many food sources available subsurface, there was no real motivation for a trout to spend the extra energy and commit the extra risk of feeding up top. Occasionally they still will, under these circumstances, but the safe bet for a fish is to feed deep.
It's important to watch the water before making your first cast, even when you see a hatch. One wrong cast, bad drift or awkward fly can spook a good run and put the fish in a position of looking for shelter rather than food.
We approached a deep run along a cliff wall below a small cascade and saw Quill Gordons emerging about 5-7 per minute. No signs of trout feeding on or even just below the surface. When these deep pools have low velocity, dead-drifting nymphs is less productive because trout have a ton of time to inspect their food. Best bet is to have something with a little bit of motion, that you can control with short strip retrieves and finish by swinging through the tail end of the pool.
So we tied on a size 10 Simi Seal Leech, and on the third cast received a hard hit from a beautiful mountain rainbow.
These Quill Gordons should continue being visible for another couple weeks, and can make good imitations both during the emergence and oviposit stage, but keep an eye on what the fish are doing before selecting your fly. There's still some black stones coming out in sizes 12-16, so keep a variety of these on-hand for when the fish start feeding up top, but your best bet for success is to also have some smaller leech patterns and larger nymphs with rubber legs available.