Phoenix AMA

The Phoenix AMA is located in central Arizona and is one of the five Active Management Areas (AMA) mandated by the Groundwater Code (Code). The Phoenix AMA covers 5,646 square miles and consists of seven groundwater basins. The AMA is characterized by a diverse mix of water uses, with a heavy and increasing emphasis on municipal and industrial uses. Multiple sources of water (CAP, Salt and Verde surface water, effluent and groundwater) are available and are being used to varying degrees. Approximately 2.3 million acre feet of water is used annually on average in the Phoenix AMA, with 1.4 million acre feet of renewable water (CAP, Salt and Verde surface water, and effluent) used and 900,000 acre feet of groundwater used. The Phoenix AMA currently is in an overdraft condition in the amount of approximately 251,000 acre feet annually. The Phoenix AMA is drained by the Gila River and four principal tributaries: the Salt, the Verde, the Agua Fria, and the Hassayampa Rivers. Other tributaries include Queen Creek, New River, Skunk Creek, Cave Creek, Waterman Wash, and Centennial Wash. Regulatory water storage reservoirs have been constructed on the Salt, Verde, and Gila Rivers and for the Agua Fria River, allowing for a relatively high proportion of surface water use in some areas of the Phoenix AMA. Located primarily in subtropical desert, the climate of the Phoenix AMA is semi arid receiving an average of seven inches of annual precipitation.

The AMA is in the basin and range physiographic province. Elevations range from less than 800 feet above mean sea level (msl) at Gillespie Dam to over 6,000 feet above msl in the Superstition Mountains in the eastern portion of the AMA.

Phoenix AMA supply and demand conditions, also known as "water budgets", are designed to illustrate a range of supply and demand possibilities. (Link to the Phoenix AMA Water Budget.)
AMA Conservation Requirements

One of the Department’s responsibilities under the 1980 Groundwater Code is to develop a management plan for each active management area for each of the five management periods spanning the years between 1980 and 2025. The Code requires that each management plan "include a continuing mandatory conservation program for all persons withdrawing, distributing, or receiving groundwater designed to achieve reductions in withdrawals of groundwater." Click here to access the Phoenix AMA Third Management Plan.

It should be noted that modifications to the Third Management Plan were adopted in May 2003. These modifications have resulted in a number of changes to the conservation programs for agricultural, municipal, and industrial water users. Click here to access the Phoenix AMA Third Management Plan modifications.

AMA Issues

The Phoenix AMA faces a number of major challenges in meeting the safe-yield goal and addressing key short and long term water supply issues:

Groundwater/surface water management/Volumetric Accounting: In recent years, the issue of conjunctive water management has risen to the forefront due to the desire of water providers to use their distribution systems to transport other water through their system; to "wheel it" to persons that are not generally recognized as their usual customers. The concept of introducing "non-regulated" water (CAP) into a distribution system that contains "regulated water" (i.e. groundwater) has created concerns of the principal parties that have yet to be resolved.

Achieving safe yield: The Phoenix AMA has a statutory goal of achieving safe yield by 2025 (or earlier). All indications are that this goal will not be achieved at our current rate and under our current programs. We registered an overdraft of 251,000 acre feet in 1998. All credible projections for the year 2025 indicate that we will still be in an overdraft situation with some improvement from the 1998 level.

Allowable pumping: Certain categories of pumping are occurring and will continue to occur without any type of replenishment obligation, making the achievement of safe yield all the more difficult. New, unreplenished pumping will increase through groundwater withdrawal permits, the creation of Type I rights, Assured Water Supply rules, and even exempt well drilling. Voluntary movement from the use of inexpensive groundwater to more expensive renewable sources of water will not happen.

Critical Area Management: While the safe yield goal is approached on an AMA-wide basis and management strategies are designed accordingly, it is clear that certain smaller areas within the AMA are experiencing water management problems far in excess of the AMA as a whole. There are areas that are facing existing physical availability problems (Carefree Subbasin), as well as areas that are experiencing severe waterlogging conditions (Buckeye, Arlington, and St. Johns Irrigation Districts). Current authorities and management strategies do not address these issues, yet they are existing and severe.

Monitoring Current Conditions: The ADWR has made significant strides toward developing a network designed to collect and analyze data pertaining to current groundwater levels, trends, subsidence, flow direction, etc. This information forms the basis of everything we do as an agency, including annual assessments of overdraft conditions

Recharge and Recovery Planning

The location and capacity of recharge facilities, coupled with a strategic recovery plan is important when attempting to implement sound aquifer management programs. Local problems, such as land subsidence, declining groundwater levels, groundwater quality, maintaining an assured supply designation, and obtaining a certificate of assured water supply, could be mitigated through a well thought out recharge and recovery strategy.

Phoenix AMA Description