There is an enormous amount of evidence that there were glaciers in this area at one time. There was a meltdown and much of the water passed through the canyons of southern Utah and northern Arizona. I thought I would point out that Kemmerer has a museum that identifies some 6000+ fossils of fish, which when I ran into it, thought it was an interesting fact this far inland. Just south of Kemmerer is one of the most beautiful gorges on earth, Flaming Gorge on the Green River.
Color me stupid, but I didn't think there were any fish in glaciers, so I don't see where fish would come from in runoff from a glacier.
ML/NJ