Check out the following Ryan:
http://www.nwfsc.noaa.gov/pubs/tm/tm35/index.htm

This is a NOAA Tech Memo "Status Review of chinook salmon from WA, ID, Or, and Ca" NOAA Technical Memorandum NMFS-NWFSC-35 (Should be at Fish/Ocean Lib. if you cant print it)

Its a 1998 publication and also has an extensive bibliography, so would provide you with a solid starting point.

I should state that the presence of only hybrids in a system does not warrant a non-listing of the species under ESA. If this is all we have left, the preservation and protection of hatchery descendants in such compromised systems is recognized as a way of gaining stock recovery. Such language is present in the current Puget Sound chinook listing (don't have the original upper Columbia listing).

I would modify your premise to an investigation of the origins and history of the upper Columbia run to flesh out just whats left to save. Good luck.