I've been there the last two Sundays for the white fly hatch. There are plenty of trout. It may be that the fish are so gorged from the brown drakes and white flies that they're able to resist day time fare.
There are no trout spawning at this time of the year, nor do trout guard their redds once they're done spawning.
I have noticed a big increase in the number of warm water fish in the slow water above the dam, though. In addition to trout, I'd guess I took at least 50 chubs and sunfish over the two evenings. Oh, and a keeper size small mouth. (Thought I had a really nice trout until I unhooked it.) Saw quite a few suckers and carp as well.
During the afternoons before the hatch, the trout were spooking if I got within 20 feet of them. And one sloppy cast would send them scattering as well.