That was a great read, too. Especially when you consider how recent it was. Took a class and filed trip once that went through a lot of scablands around Othello.

There really has been a whole lot of change here in the PNW since the last glaciers retreated about 15,000 ybp.

Here's just a few that geologists have shared. In no particular order.

When Glacier Peak erupted it sent the Sauk, Suiattle into the Skagit from the Stilly. Before that, the Upper Skagit, Cascade, etc were Stilly tribs.

The S Fork Nooksack was a tributary, or actually the whole thing, of Friday Creek into the Samish. May explain Friday Creek Springs into the 1900s.

The White, of course, was a trip of the Duwamish.

At one time, the White went down South Prairie Creek.

Most of Puget Sound streams, at the peak of the last glaciation through the retreat, went out the Black/Chehalis.

Our streams have naturally moved a lot, mostly in response to our volcanoes. But when folks talk about a particular stock of fish being the end product of millions of years of evolution it just ain't so. They formed separate stocks very very recently.