If you've heard of it, it will be crowded in July

For instance, the Green is reported to have 40,000 fly rods and 20,000 fish
per mile G

but,

I used to spend a couple weeks each year, running dogs, in the Unitas
Forest, East and South of SLC ... south of Evanston and above and South
East of Park City, Ut ... basically everywhere the altitude is high enough
to keep the desert at bay

In that zone, if it's year round water, it's probably got nice fish, is very
UNtechnical, and in beautiful country. I always brought my own lodging
with me, cased caddis like, and it's remote enough that you might have a
little trouble finding a non-camping place to stay, but there is laid back
fishing to be had

LOTS of wonderful water is within 5 hours of SLC, but it's nearly as hard to
pick a fishing hole for someone else as a spouse ..... many of the places I
most like are both crowded and very technical, but the area above was
neither the last time I was there ( roughly 4 years ago )