Good and bad news. Good news: the river is fishable on both sides way above the hatchery. The reservation boundaries are well marked or gated. The boundary is at least 5 miles upstream of the hatchery although most of this area is in a unfishable canyon. Anything from the hatchery (there is a small local closure) down is OK and this gives you about 3- miles of water.
Bad news: steelhead fishing sucks so far this year. I have friends that have fished it for steelhead for 2 months with zero fish. Bait fishers are doing OK on salmon.