Prescott Active Management Area

Prescott AMA definition.The Prescott Active Management Area (AMA) was created by the 1980 Groundwater Code and operates under the direction of the Arizona Department of Water Resources. The Prescott AMA is one of five Active Management Areas within Arizona that were instituted to reduce localized groundwater overdraft and achieve safe-yield by 2025. Safe-yield means that the amount of groundwater pumped from the aquifer (underground water supply) on an average annual basis must not exceed the amount that is naturally or artificially recharged (returned to the aquifer).

Location.The Prescott AMA encompasses roughly 485 square miles in Yavapai County and includes Prescott, Prescott Valley, Chino Valley, Dewey, and Humboldt. It contains two subbasins (partial watershed areas). The Little Chino subbasin contains all of Granite Creek which begins in Prescott and runs northward to Chino Valley. The Upper Agua Fria subbasin begins near Prescott Valley and contains the headwaters of the Agua Fria River which runs southeastward to Humboldt. Each subbasin contains economically significant amounts of groundwater found at depths ranging from just below the soil surface to a depth of 500+ feet. The Prescott AMA is within the Verde River Watershed.

Climate and Plant Growth of the Verde Valley

Activities.The Prescott AMA monitors agricultural, municipal and industrial water users within its boundries. In 1995, agricultural users grew irrigated crops on 1,656 acres and accounted for 35% of groundwater use within the AMA. Permanent pastures account for 67% of this acreage. Municipal users accounted for 61% of the total reported groundwater use in 1995. This does not include private wells pumping less than 35 gallons per minute for domestic use. Industrial water users consumed 4% of the total reported groundwater use in 1995. These are all located in the Upper Agua Fria subbasin.

Groundwater Recharge.Water must continually be replenished to the aquifers through a process called recharge. During recharge, water infiltrates (enters the soil) and percolates (flows downward) until it meets an impervious layer or the water table. In this manner, water is delivered into aquifers and recharges them. The Little Chino Subbasin receives significant recharge through runoff and underground flow originating in the Bradshaw Mountains located on the south side of the AMA. The City of Prescott also pipes treated sewage effluent to a location near Ernest A. Love Field for artificial recharge to the aquifer. Further recharge occurs along Granite Creek between Prescott and Chino Valley following periodic flood events.

Planning.The Prescott AMA is currently planning for the next management period: the years 2000 to 2010. Some of the issues being considered are:

• augmenting water supplies by importing it from outside the AMA,
• increasing underground water supplies by increasing recharge,
• continuing efforts to maintain or improve water quality,
• considering and quantifying the water demand of riparian areas to include it in the reported water use, and
• increase in water demand due to rapid urban and suburban development occurring within the AMA.

In addition to working toward a sustainable water budget, the Prescott AMA provides:

• educational programs,
• training for teachers in water resource curriculum, and 
• cooperates with local organizations to meet their goal of sustainable water resources within the Prescott AMA. 

Source: USDA. Soil Conservation Service.