There is a Arizona gardening forum here you could try posting this to.

Have you considered ditching the grass and going with native drought tolerant/desert plants?

Mushrooms in AZ indicate far too much water. What is your watering schedule? How often do you water and for how long? Also, where are you in AZ? I'm guessing not Flagstaff, but that's just a guess.

Have you fertilized or used any herbicides this year? If so, what have you used?

Could also be grubs. We had the Japanese Beetles lay them in our grass and they ruined it. We use grubgone! every year on it now.

Grubs are a late summer problem, not spring. Using an insecticide, just because you had insects once, is a very poor practice. It's damaging to the health of the soil and wastes money. If you think you have grubs in late June, dig up 1 square foot of turf. If you can find fewer than a dozen grubs, your lawn is good to go. If you find an uncountable mass of grubs, then use an insecticide. But don't do it just because.