just wanted to add something, If the Upper Columbia contains a majority of hatchery/ wild fish hybrids It would make sense to me that the 100% native population would be threatened. (more hybrid fish competing for native habitat and food). There are probably some natives hanging on there, Therefore giving all the more a need of an ESA listing for the remaining wild fish.
If an ESA listing occurs, especially an "endangered" rather than "threatened", The hatchery steelhead fishery would surely come to a halt, to allow for wild steelhead populations to increase.
good luck with your study.