Canyon Creek of the East Fork Lewis Drainage is a well known Washington classic. At the medium to low end of flows it is IV+ and a superb new creeker run. At the medium high to high end of flows it becomes significantly more pushy and intimidating. However at these flows some of the drops clean up and the rapids become more "quality".
Flow is usually based off of the East Fork Lewis. Correlation between flows is pretty good. There is a USGS staff gauge located just above the put in that will give you realtime flows, however this is above the Fly Creek confluence (which provides or doesn't provide a significant amount of flow).
EF Lewis Reading CC Flow
<600 Go home
600-800 Low but okay
800-1100 Med Low, great first time level
1100-1500 Med, starts to get pushy but drops still "unclean", watch yourself
1500-2200 High, the sweet spot
2200-? High high, character will begin to change to big water. She still goes.
The character of the run at flows below 2200 is pool drop with one significant boulder garden.
From the put in you will encounter a mile or so of class II-III. As the rapids become shorter, steeper, and more pool drop keep your eyes open. Below one of the class III drops the river will bend to the left and enter the gorge. There is an eddy on the left above the entrance to catch your breath and eyeball everything. From the eddy you will distinctly see where the canyon pinches down into the gorge.
The first horizon line out of the eddy is Entrance Drop. It is a short, mankish drop; run center right. This puts you in the eddy above Swizzle Sticks. Run the obvious line down the right side into the gorge. You will now be in a surgey, boiling gorge that will rollercoaster you around several bends. There are no major hazards in here (as of writing this), enjoy the ride. You will exit this mini gorge just upstream of the bungee bridge.
In this river wide eddy you are immediately above S Turn. Boof the slot immediately in front of you and make the turn to the left. Follow the S, just make sure that you are straight at the bottom. At higher flows you can get hammered here if you aren't on your toes.
After S turn is Terminator, almost nonexistent after the 2006 floods. If it's higher water hang left through the turns to avoid the large breaking wave hole in the center of the rapid. Continue on through 2 class III rapids to the Thrasher twins.
Prelude to Thrasher is a nasty broken ledge with an undercut in the left corner and a potentially problematic current dynamic on the entrance. At low water the danger is less, at high water you can run the far right sneak. <