in 2008 not too long after they opened the spillways, we caught four walleye, On jerkbaits and Zig JIgs, over the course of a few hours. I released each one thinking there was no way I would catch another. We also caught White Bass, LMB, and saw crappie in a shallow protected area.
Those walleye are still there and are still eating. Not knowing any better, I would believe that a jerkbait fished at night during the summer when the water was off has a good shot at catching a walleye.
In is interesting (and frustrating) how different water levels are better for some areas and less good for others. 5000-10,000 CFS is great immediately below the dam. In reduced the number of small fish that you catch and makes the larger trout eat more often. They are often beasts in that fast water.
The worse the weather the better the fishing if for no other reason, it keeps the number of boats to a reasonable level. It can get to be a zoo there at times and 15-30 boats constantly buzzing over the top of the fish starts to shut them down regardless of flow rate. I'm been there and seen it happen.
You will lose some fish with the barbless jigs, but it is legally required in some areas and a good idea all up and down the river. You can release them so much quicker which can mean dry hands for you on a COLD day and it has to be easier n the fish as well. Less time spent releasing a fish = more time with your jig in the water = more fish caught. YES, it sucks when a big trout gets down current and wallows on the surface until the hook comes out. Suck it up and better luck next time. A barbless hook also comes out of you a lot easier. Ask me how I know.
Sounds like a Great trip. You are crazy to fish in < 10 degree temps. Screw that. I'm not man enough for that crap.