Got my canoe on Scanewa about 3PM. Surface temp in the "Cowlitz" portion of lake was pretty consistent at about 57F. Once you got into the "Cispus flow" portion of the lake temps dropped to about 53F. Not surprising, considering the kind of winter, spring, and summer we've had.
An interesting lake. It is best described as "3 Channels". Boat ramp is in the Cowlitz Channel. Once you launch you can work right (downstream) and down into the main lake, or left and just go upstream as far as your boat will take you up the Cowlitz. Going down stream you work around a long "U" after which there is a channel off to the right (rather narrow) and that probably goes to the dam (it's a long channel and I went down a ways, but stopped before seeing the dam.. the water gets deeper as you go down this channel though so the dam is probably not too far down). Going straight (or left) gets you into the main lake and then quickly into the "Cispus" influence.
I trolled small crankbaits down the Cowlitz "influence" and channel going toward the dam and then partially up the "Cispus" influence with no luck.
The Cowlitz "influence" portion of the lake, the main lake, and the channel to the dam were very murky. It was the white-green murky typical of glacier runoff (e.g., the Cowlitz). I did see a few smolt jump in the murky water, but (other than that) no sign of fish on the depth finder or any hits from my end. However, the folks anchored in a boat directly across from ramp were landing what appeared to be a nice fish as I put my canoe in. A party returning from fishing up the Cowlitz portion (to the left from the ramp) came back in as I was launching and reported limiting out. They seemed happy and successful.
There is a very distinct "line of demarcation" in the "Cispus influence" portion of the lake where the water very quickly turns from "milky-green" to "extremely clear". Two small boats were anchored just inside the "clear" water and were apparently doing very well. The conversations I overheard on these boats suggested that they were using worms and/or powerbait. I switched to a small tandom spinner with a "wedding ring" trailer and put some power bait on the hooks and trolled it on a short line with no weight into the "clear" water. I immediately started getting hits and had one nice rainbow up to the boat.
Despite the powerbait (which I don't like to use) the hook was stuck in the outer part of the lower lip, so I was able to release it without taking it out of the water or even touching it (just grab the hook with the needlenose and twist gently). The fish I got to the side of the boat wasn't "thick" and "well fed" like eastern washington trout. This would suggest a limited food supply. Several more hits, but no solid connections, in the "clear" water and a few more as I got back into the "green-white" murk.
Bottom line here is that there seems to be some fish in the lake. Best strategy for the murky water is probably to use Powerbait and/or worms near the bottom (still fish).
However, I think there is an underutilized opportunity for fly fishers to do well on "under 14 inch" Rainbows which sport full river coloration (rich color, real dots, and a definite non-right out of the hatchery- look) in the "Cispus influence" portion of this lake, which appears to go for at least a half a mile, if not a mile or more beyond the "line of demarcation"... I didn't go too far up because time was running out.
May head up to do just that in a couple of months