From the perspective of the smolts alone, there is currently anywhere from 10-30% smolt mortality PER dam as they head to the ocean. Most apparently are killed form the tubines. You can read this in the Corps helpful "salmon and dams" brochure where they tell of how they steer 80-90% of fall chinook smolts and 70-80% of spring/summer chinook smolts away from the turbines at each dam. I have seen a graph of counts thru the 7 dams (can't find the webpage) and only a small percentage make to the ocean in a given year (1-10%).

-------When a smolt "swims" to the ocean, their heads are pointed upstream.-------

So they don't actually swim, Rather they count on the river's current to take them out to sea. It shouldn't be too hard to figure what one factor limits smolt ability to make it out sea (but it apparently is for most). If all dams were removed, the speed they would make it back to the ocean alone would reduce many other death contributing factors to a minimum (barging has not been sufficient means to remedy this). If you don't have smolts, you don't have adults. Of course if there were all those smolts, could the ocean even support them with current commercial constraint on food sources. Hey, maybe we don't want too many smolts!! That'll be the next thing people will try to argue.

From an economic standpoint, alot of the jobs we justify keeping the dams for are subsidized thru tax dollars. Meaning they aren't turning a profit. We don't hear much about them from that standpoint, But I can't decide whether jobs thru tax dollars are either good or bad. I don't think there are very many companies making an actual profit in todays economy.