The Eastern Plateau Planning Area is unique in that it is composed of one groundwater basin, the Little Colorado River Plateau Basin. The planning area is relatively high in elevation and is geographically diverse with the highest peaks in the state as well as deep sandstone canyons and large mesas. Almost two-thirds of the land area is under tribal ownership. Elevations range from over 12,600 feet in the San Francisco Peaks north of Flagstaff to 4,200 feet where the Little Colorado River exits the Basin at Cameron. Parts of three counties are contained within the Eastern Plateau Planning Area: Apache (90% of the county), Coconino (41%) and Navajo (89%) counties. All or parts of three Indian reservations are located within the planning area – the Hopi, Navajo, and Zuni reservations. San Juan Southern Paiute tribal members occupy lands located within the Navajo reservation. The Joseph City Irrigation Non-expansion Area (INA) was designated west of Holbrook in Apache County due to insufficient groundwater to provide a reasonably safe supply for irrigation (A.R.S. § 45-431) (Figure 2.0-2).
Much of the planning area is sparsely populated. Flagstaff is the largest metropolitan area with almost 52,900 residents in 2000 and an estimated population of 64,200 in 2007. Other population centers include Show Low/Pinetop/Lakeside, Winslow/Holbrook, Page, and Tuba City, Window Rock, Chinle and Kayenta on the Navajo Reservation. The 2000 Census planning area population was almost 250,000.
An annual average of about 170,500 acre-feet of water per year was used during the period 2001-2005 in the planning area for agricultural, municipal and industrial uses (cultural water demand). The water supplies utilized to meet these demands include primarily groundwater (104,800 acre-feet), surface water from the Colorado River and other streams (50,800 acre-feet) and effluent (14,900 acre-feet). The planning area has a large industrial water use sector due to the presence of several electrical generating stations, large coal mining operations and a paper mill. Industrial water use is currently about 83,100 acre-feet per year (AFA). Municipal sector average annual demand is approximately 45,000 acre-feet. Agricultural demand is relatively small-scale with an estimated annual demand of 42,400 acre-feet.