With so many skilled anglers fishing the Chilliwack/Vedder system and harvesting virtually every hatchery coho they catch, it is no surprise that some people find there are more wild fish at the end of their lines, especially when fishing further up the river.
In fact, I'd be willing to put money on the assertion that the higher up you fish, the fewer hatchery fish you are going to catch.
The same holds true for steelhead.
There is some insanely good pocket water in the upper river a fair bits away from the meat holes and crowds. Fishing there is good and peaceful. But the chances of getting a hatchery coho there are almost the same as scoring one on the Squamish river.
They pass by in the night Milo, keep your hopes high.