CM -
It was my observation that river systems really began to unravel when the logging moved from the lowlands up int the mountains. Once that got above that 2,000 to 3,000 elevation (depending on where in the Cascades) they were on steeper ground and where rain on snow events were much more frequent.

In much of the region that was after WWII. Of course that move upslope was on steeper ground and railroad logging was not longer possible. In addition to the moving on to steeper ground the cut rates went up (smaller wood and more efficient harvest methods). The result was that larger portions of the basins were cut in short periods of time and at the same time the harvest was occurring in the most vulunerable part of the watersheds. Even though much of the damage was above fish bearing waters that water does flow down hill and the snow ball of damage rolled to the river mouths (and beyond).

Tight lines
Curt