True, these flows do get a some late coho, I recently caught a relatively clean one on the vedder as well though...also saw an even cleaner ho caught on the vedder yesterday...big roe gob by an angler fishing in the sticks and trees along the banks of the lower river...with that in mind, I suspect some late run fish could be found in a number of the systems throughout the valley.
As far as I'm concerned though, it's steelhead season, and I release any coho I catch these days to spawn and continue their late run numbers, regardless of how clean. This way there will always be some around, maybe even more as the years progress and more survive to do their duty.
Always nice to have incidental catches while fishing steel though...
Good luck out there,