Uh not at all. Not even close, in fact. :) The Columbia River is probably
the single largest source of hydroelectric power on this continent. Virtual
all power in the northwest is generated by hydro, mostly from this system
(and a few nuke plants). Even the Grand Coulee dam is in the way, and it may
still be the largest dam in the world. You'd have to cross Bonneville Dam,
The Dalles, John Day, McNary, Chief Joseph, and Grand Coulee (which doesn't
even have a fish ladder, let alone a lock). And those are just the federal
dams, there might be a few others. Some of the lower dams have locks, but
the uppers sure don't... I know there's dams on the spokane river as well.
So to answer your question, no, they're not navigable that far up.
You could (relatively) easily navigate into Seattle or vancouver or victoria
or something like that however.