Tom,
You'll find through the research the main problem is smolt, both hatchery and wild fish, making it down to the ocean. The various agencies have tried all sorts of stuff, from collecting smolt behind the dams and barging them (conclusive evidence points to that actually REDUCING the adult return rates) to installing turbine screens, to killing pikeminnows, etc. etc. etc. A vast majority of the money spent to recover anadromous fish has gone into these "techno" fixes...and yet, we still get 0.5% return rates.
Further evidence that dams are the problem is simply looking at coastal U.S. rivers with NO dams and river systems in Canada and Alaska that have NO dams. Those rivers typically have smolt-to-adult ratios of 30% or more. A good comparison would be the Fraser River and the Columbia...both about the same size...not that far apart, maybe 400 miles. The Fraser River has (1) dam on a small tributary, the Columbia has over 200 dams including a bunch on the main stem. The Fraser river fish returns are still measured in the 10's of millions...while the Columbia is rarely even at 800,000...Wonder why??????
Even further evidence that dams are the problem are the "good" times the fish in the Columbia have experienced the last 3 years. All because of extremely high-water conditions on the rivers. The corp of engineers had no choice but to release water and as a result the smolt were flushed to the ocean. I'd guess the smolt-to-adult returns were in the neighborhood of 3% for the "good" years. Think what they would be like with smolt-to-adult return rates of 30%+, which is common on rivers without dams...
Another key piece of evidence is to look at the Hanford Reach, you'll find that referenced many times. Its one of the last good rearing grounds on the Columbia system that still functions as an undammed river. The return rates for salmon there are again in the 30% range...
The evidence is so crystal clear its scary, the research is the BEST ever conducted, and the solution is so easy to comprehend, most 3rd graders would understand it. Yet, the Shrub administration denies logic, science, and common sense in their tireless efforts to end hunting and fishing in North America...and the idiots continue to vote them into office...pretty sad.