A variety of cased caddisfly larvae, probably mostly Neophylax, have clustered along the backside of a rock in fast water. There seem to be some Helicopsychidae larvae clustered along the bottom, and a few other taxa are mixed in. It's interesting that several larvae have especially large stones placed over the front openings of their cases, perhaps to block the case off for pupation.
It does seem to be the wrong time of year for Neophylax to be pupating, but that was the ID given for one of these which I collected and photographed up close.
A crayfish chews on a Hexagenia limbata nymph shortly after a small Hex emergence. I didn't catch any fish, but playing around with my flashlight and camera in the rocks proved productive.