I am going to start as usual on the Metolius River and this week we are going to work our way down from the headwaters, through the Upper River, into the Middle River and explore the top end of the Lower River too. 
Hopefully this will also let you understand the distinct sections, and where the boundaries are so you can also understand the river a little more. 
We always refer to the Upper River as the area from the headwaters to Gorge Campground. 
The headwaters stretch from Riverside Campground to the confluence with Lake Creek is the smallest and most intimate water you will find on the river. It is a sweet spot for a light Euro Nymph rig using the ultralight leader set up I wrote about in last weeks report, and a single 2.8 mm to 3.3 mm perdigon. It is also the spot where you are most likely to hit some fish this coming week on Golden Stone dries (and nymphs). You will also encounter summer hatches of Caddis & PMD’s all over the river, including the upper river. Fish the complete cycle of the mayflies, and the pupa and adults of the caddis. You might encounter days of the caddis larva being important with a tan free living caddis (net builder caddis/Hydropshche) is a common caddis here and the larva do not build cases and can be “in the drift” at times. It is far from my 1st choice of flies to tie on now, but consider adding some to your fly box to compliment the tan pupa that I have been telling you about in report after report. 
On the PMD’s fish the entire cycle through the day. Nymphs will be in the drift almost anytime, emerging duns will occur usually twice a day and those times will be around 11 to 3 and again after dinner. Spinners (females are rusty and males are yellowish orange) at dusk. During emergence a lot of the emerging duns become cripples. If you are carrying all of the above, you are not fully ready for the day of technical spring creek fishing. Add your Suppleflex or Finesse 12 foot leader and extra 6x tippet to the equation and you have gone from JV to Varsity my friend.
The Middle River starts at Gorge and goes to Bridge 99, so this includes the Canyon Pools, the Hatchery area and so much good water it is arguably my favorite on any given day. Some of the most famous pools and eddies on the Met are in this stretch. 
Through this area, PMD’s are also the main hatch, but so far the Green Drakes are holding on with a daily hatch between 2 and 6. That won’t be a 4 hour emergence BTW, but during that window of time during the day this week make sure you have nymphs, emergers, cripples and duns. And if you are an early AM angler, put a spinner in the box. Did you know Green Drake Spinners are rarely encountered by anglers? But when you do run into the opportunity you want to be prepared! Right?
Blue Wing Olives often emerge in the shadows of the evening light on the middle river. A Film Critic, Sparkle Dun and a KD Dun #20 will be smart choices to out over a tough trout. 
Summer Caddis hatches and small Stoneflies like Yellow Sally’s and Little Olive Stones will provide good dry fly opportunities in the evening mostly, but also in the afternoon during the heat of the day. Nymphs of the little stones are not overly important on a day to day basis, but going to the Metolius without Tan Caddis Pupa this time of year is not something you want to do. Also, you have to check out the NEW Missing Link Yellow Sally we got in this week. OH MY it is a Metolius fly for sure. The profile is all about staying low in the film and we know the trout love that on this river. 
The Lower River starts at Bridge 99/Lower Bridge Campground and heads to Lake Billy Chinook from there. I only focus on the area from Bridge 99 to Candle Creek CG myself, but I know friends who ride Mtn. Bikes lower and find good fishing. It’s a much more wild river in so many ways if you do that. 
All the same hatches as listed above for the middle river will occur here too. 
Any day now the Lake Run Bull Trout ought to show up to the Middle River. They won’t spawn in the tributary creeks for a while yet but they will come out of the lake soon. This is the time for your 8 weight rod and big streamers.