I live not far from where Columbia river comes out to US from Canada, in US portion of Selkirk Mountains. This is north of Coulee Dam.

It's good that salmon can come into this area but smelter from Trail, BC has been polluting upper Columbia river for about hundred years. With chemicals and smelter sludge. Fish is not edible, sand is black from sludge.

Salmon may have reached upper Columbia river, but water in that part of the river is heavily polluted.

And south of Coulee Dam, there is storage of nuclear waste, just north of Richmond, WA - Hanford site. Nuclear waste already leaks into Columbia river, north of Tri-Cities area.

So in my opinion, human created disasters in the Columbia river, rank in this order: nuclear waste at Hanford site > smelter at Trail, BC > Dams without passage for fish.

Sorry for typos, typing from phone.