I did a research like this when in college.
I wish that I could remember the references for you.
The conclusion was that hydroelectric dams were bad for fish. Adults do just fine getting through the ladders where available; however the fry just don't have a chance coming down.
If they don't get chopped up by the turbines, the fall and pressure gradient will nearly kill them which makes them easy prey for scavenger birds and fish. But they don't tell you this, they just blame the squaw fish and put a boundy on them to steer the public away from the affect of the dam.

You might want to look into the latest development of the Bonnevile project and get some numbers for your statistics. I believe that there is a greater survival rate since this new smolt passage was in placed.

Good Luck.