you forgetting the skok river (Cresent Lake) Tacoma Hydropower project...?
the lack of freshwater flushing into the canal during periods of heavy rainfall in my opinion has to be the biggest contributor to the low oxygen problem...Think about how much water is no longer allowed to filter out onto the delta as it did for thousands of years. The damn dam has got to go.
this reminds me - where the heck is the progress on the Elwha River removal....Again the damn dams, have got to go.