The Southeastern Arizona Planning Area is composed of 14 groundwater basins that vary significantly in size. Elevation ranges from 10,713 feet to 1,830 feet. Cochise County is entirely contained in the planning area as well as portions of seven other counties: Apache (0.1%), Gila (22%), Graham (95%), Greenlee (92%), Pima (6%), Pinal (27%) and Santa Cruz (44%) counties. Most of the San Carlos Apache Reservation, the fourth largest reservation in Arizona, is located within the planning area in parts of six basins: Aravaipa Canyon, Bonita Creek, Dripping Springs Wash, Lower San Pedro, Morenci and Safford basins.
The 2000 Census planning area population was approximately 188,300. Basin population ranged from 21 in the Bonita Creek Basin to over 78,000 in the Upper San Pedro Basin. Sierra Vista is the largest metropolitan area with about 44,900 residents in the incorporated area and an additional 16,500 residents in the unincorporated area southeast of the city in 2006.
An average of 515,100 acre-feet of water (including effluent) is used annually in the planning area for agricultural, municipal and industrial uses (cultural water demand). Of this total, approximately 84% is groundwater. The agricultural water use sector is the largest user by far with an average annual demand of approximately 440,000 acre-feet. There is significant agricultural use in the Douglas, Safford and Willcox basins, with over 88% of the total agricultural demand. Most of the Douglas Basin contains an area designated as the Douglas Irrigation Non-expansion Area (INA). INAs were established in areas determined to have insufficient groundwater to provide a reasonably safe supply for irrigation. Average annual municipal demand in the planning area is approximately 40,500 acre-feet per year (AFA) and industrial demand is approximately 34,550 AFA.