They're typically a good mix of wild and hatchery. Like most areas throughout the US, this topic is highly controversial though. The hatcheries in Washington are primarily used for supplementing fisheries with hatchery fish; which, according to some works against the survival of the native gene pool. You then get 2 groups; those opposed to hatchery propagation and those in favor of. In Eastern Washington, native steelhead are federally protected. However, the number of returning hatchery fish are so great that it is typically deemed ok to fish for steelhead because the risk of incidental take to the native fish is reduced. The fisheries also wants to remove excess hatchery fish from the system so they don't water down the native gene pool.
I'm really tired of this discussion and prefer to be more simplistic in my approach. If I can fish, it's a good thing.