i thought hydropower screws up the ecosystem of rivers pretty badly. LIke fish unable to spawn and all that.
Not to mention that the dams in Washington state do account for spawning/migration and slow down flows at certain points of the year.
Earlier attempts at fish ladders saw rates as low as like 3% for certain species of fish, per ladder/dam. Even if 50% of salmon got up them, if they have to pass 5 of them on the way to the spawning ground that meant 97% of salmon wouldn't make to the spawning grounds.
Also, obviously, the ecological effects aren't just "tasty fish can't make babies". The impact on seasonal floodplains and sedimentation is huge by itself.