Well, I finally made it out to the Swift on Feb. 8th for a few hours. I believe that the flow was down to 314cfs that morning which was the lowest flow since the holidays. That was enough to get me out there. All told, I caught one small rainbow in two hours. I didn't see anyone catch any trout and from the high vantage point just below the "pipe" I couldn't see any trout either. Five weeks before I saw plenty with even higher flows. I think that the answer is that the prolonged high water (500cfs in January) just scatters the fish. The same thing happened in '06. Once the water gets down into the low 200's the "pipe" will attract them again.
My favorite Hendrickson nymph - a year ago I posted the recipe for the Hotspot, a fly with a bright contrasting band of color. The same idea is at work here. A standard hendrickson nymph with a thorax made of RED dubbing. It's all that it takes to set this fly apart.
Try it out and think SPRING!!!!!