The Metolius is seeing a big increase in Green Drake hatch activity. There are 2 distinctly different “drakes”, and size is a big factor in matching the hatch. It get’s complicated when they are both hatching in the same hole and at the same time. But that is the game we play. The bigger drakes are #10 and the smaller Flav’s are #14’s. Emergers, Cripples and Duns are all important and from day to day, hatch to hatch, weather conditions and light intensity, you may find one fly worked well yesterday but not as good as another pattern tomorrow. Do you love that? I do.
PMD’s #16 (nymph/emerger/cripple/duns/ and Rusty Spinners)
BWO’s #18 (nymph/emerger/cripple/duns/ and Olive or Rusty Spinners)
Mahogany Duns #16
SO MANY Caddis #18 (Yellow) #18 (Charcoal) #16 (Olive) #14-18 (Tan) #8-12 (Orange). Deep Pupa, Emerging Pupa, Adults, Egg Layers and Spent Caddis are all important flies to have in the box. It’s not just a simple matter of tying on an Elk Hair Caddis on technical Spring Creeks. 
Also the Little Olive Stoneflies are everywhere now. If you see fish rising a lot and you can’t decipher what in the heck they are eating, lean close to the water and look to see if little stones are floating by, bedraggled in the film. If so, a small Olive CDC Caddis, Hemingway, or Double Wing CDC Stone is good. We often trim the hackles flat on the bottom to get the effect of the low floater. 
Golden Stones, Salmonflies and the really big Willow Flies are on the menu and can be locally important deepening on what spot you are fishing. It seems the lower water in the Upper River above Lake Creek has moved fish down river, there just isn’t the holding water to keep them protected in that upper mile and half maybe. I do know for sure that this summer the Golden Stones (a typical staple) have not been as productive way up river. 
Nymph action is very productive at Non-Hatch times with Euro Nymphs. 
Bull Trout fishing is good to very good with Streamers. 
We are in the best 6 to 8 week period of fishing of the year on the Metolius in my experience.