SG & CM I am trying think of an example to let folks the force of velocity plus volume. In 2010 in the Satsop flood I stood on the banks of the outlet at the hatchery. The river sounded like jet engine with the volume that was going by trees and all, it was ugly. I could hear boulders bouncing off the sandstone bottom and banks. It was like I threw a handful of large rocks in the cloths dryer. If you remember CM I had over 200 cubic yards of gravel blocking the hatchery outlet including a 24 diameter full length tree with root wad and all.

The gravel movement off the cliffs upstream was huge as these are glaciar till lands and the cliffs are gravel over a hundred feet high. So erosion can be very bad but also it can be good for the fish. It is the erosion that continuously resupplies the rivers and streams with gravel and with it comes the topsoil. I am sorta jumpy about setting CM off with how salmon clean up a stream but it is a fact. So flood driven erosion is normal and the nature of the flooding is the same. The difference is really people as when it affected 100 rural folks no big deal now it is 1000 bigger deal. As size the biggest flood in the Satsop I know of was in the 1930's and water got into Elton's barn. The fish survived as somehow the river and fish work things out. Add humans.......not so much.