Isn't that entire Kalama spring chinook run artificial?

Seems I read awhile back that historically, there were no spring chinook in the system. Always perplexed me why most years that run struggles since the little guys just have to make a right turn at the mouth and it's a short shot to the estuary. I know it's not that simple but they don' t have any dams to contend with either.

Inferior stock used? Reduced plants?