From what I am gathering it's a combination of many factors. Increased natural reproduction of chinooks, increased invasive ( which is omitted) and back to back winter kill on the ecosystem.
It may be a tough road ahead . Hope the steelhead do survive and this could possibly be a return to a more natural state of the lake ,, possibly = Atlantic salmon & lake trout.
Atlantic catch rate on the lake is very high right now for 2 year olds this season so far.