Re: southern utah
I know a place in southern Utah in the middle of the canyons where a cold stream runs out into a huge shallow rocky delta before flowing into a warm river. You can walk through the water (1 ft deep), and fat trout jump out of your way. Casting is easy, and catching is good in July.
I'm not telling where it is, but it proves that there is fly fishing even in some of the canyons which are primarily desert.
Joseph T. Sinclair, Author, San Francisco Bay Area