Even if the spawn make it through the dams, they won't be able to come back when they reach spawning age.
They need to invest tons of money in salmon ladders and naturalization, for example, like we are doing in BC. That would be quite the project for the Grand Coulee dam, as I remember it being quite large.
Hopefully this is the first step in the massive commitment that will be needed to restore the salmon population there. The salmon run is such an important part of the ecosystem.