Where to begin....

The hatchery environment is significantly different from the natural. Water temperatures are different, water velocities are different, food arrives in different locations (surface vs. benthic), and so on. Disregarding the domestication issues, like not having to deal with predators and so on, the fish that survive in the hatchery are different from wild fish because the environments are different. In order to survive in the hatchery the fish must evolve, and this involves different genetics. When those genes are injected into the wild, the result is poorer performing fish; exactly what we see time and again.

Some hatchery reared fish do survive in the wild. They evolve each generation, so long as "bad" genes are not re-introduced.

The best information we have on "natives" is analysis of the genetics of the various stocks. In many places, there is no evidence that hatchery genes have been incoprorated into the wild. In others, they have been successful. In at least a few places, the hatchery fish have established a separate sub-population within the watershed. They are staying separate, probably due to spawn timing and maybe spawn location.

If you want wild fish, naturally reproducing and evolving within the watershed, then the best thing (genetically) is to keep mal-adapted fish out. If it really is not imporatant to have naturally spawned fish the plant the heck out of the system and fish the heck out of it. For whatever reason it appears that hatchery and wild steelhead can not coexist in the same watershed; IF ones wants to have a large wild fish population.