Ask Mr. Smarty Plants

There are a few native shrubs for your area that would get to about the size you are looking for: Mountain Mahogany Cercocarpus montanus (alderleaf mountain mahogany), Red Oregon Grape Mahonia haematocarpa (red barberry), and One-seed Juniper Juniperus monosperma (oneseed juniper).  The first is mostly evergreen, the second two are fully evergreen.  Since they are all native to upland sites in your area, they should require less water, although all plants need water for the first year or so at least when you first plant them to establish their root systems.  To create a hedge, you may want to try to plant these relatively close together, and how closely you space them of course affects how many you will need.  Follow the directions given from the nursery for whichever plant you buy.  If you plant them five feet apart, you will need about 18 shrubs.   Just take your 90' length, and divide it by the spacing you decide to use to get the number of shrubs required.

There are some alternatives to a hedge you may want to consider, since it will take a little while for the shrubs to grow to 8 feet.  You could build a fence and grow vines on it.  You could also plant a few trees in combination with either the vines or some slightly shorter shrubs, say 5 feet high or so.  You could also build a berm, or a mounded area, ranging from 1-3 feet at the highest point, and then plant shrubs, trees or vines on top of that.  The more layers of different size plants you use, the more completely your view will be screened.  If you would like to explore some planting alternatives for your area, you can go to this link: Arizona Recommended Species, and narrow your search by the type of plant you are looking for.

Cercocarpus montanus

Mahonia haematocarpa

Juniperus monosperma