In 2019, only 18 salmon returned to the lake.
Further 4 dams in the Snake River are not used for hydro power, nor are they for flood control. They were used to try to make Idaho a major sea port -- despite the fact that Idaho is several hundred files from the ocean.
https://discoversawtooth.org/what-happened-to-the-red-fish-o...
In this case it is true that hydropower is cheap and clean. However, the negative externality of destroying the salmon run is much more than "some fishis" that some Indian tribes cared about.
Aboriginal annual salmon catches have been estimated at over 10 million pounds for year. On top of that, the migration of pacific salmon upriver represents an enormous transfer of nutrients upstream. Salmon are a keystone species and are vitally important for the health of forests.
Unfortunately, the salmon run cannot easily coexist with the dams. Yes, there is value in the hydropower. Yes, it is cheap, clean energy. But it is certainly not without cost. We could be reaping the benefits of one of the largest animal migrations on our planet in a sustainable way. Even disregarding the cultural importance to native peoples there is still enormous economic and ecological value in having a healthy salmon run.
For comparison, the US alone currently harvests 100's of mil pounds of salmon a year. Alaska alone produces 500mil pounds last year (and this was the lowest in decades). Norway harvests around 3 BILLION pounds of salmon a year.
Overall, generally speaking, the ecological condition of the continental US is probably better today than at any time in the past century.