The statutory management goal of the Pinal AMA is to allow development of non-irrigation uses and to preserve existing agricultural economies in the AMA for as long as feasible, consistent with the necessity to preserve future water supplies for non-irrigation uses.
The Pinal AMA covers approximately 4,000 square miles in central Arizona. The topography consists of gently sloping alluvial basins separated by north to northwest trending fault-block mountains. Land surface elevations range from 1,000 to 4,000 feet above sea level. The AMA consists of five sub-basins with unique groundwater underflow, storage, and surface water characteristics. These sub-basins are Maricopa-Stanfield, Eloy, Vekol Valley, Santa Rosa Valley, and Aguirre Valley. The boundaries of the sub-basins follow the highest elevation of topographic divides separating areas from where surface water runoff emanates. The boundaries that separate the Eloy and Maricopa-Stanfield sub-basins also signify the presence of groundwater divides that define the extent of groundwater underflow. Migration of groundwater underflow between these sub-basins is limited or non-existent.
There is a critical need to develop water management programs to “preserve future water supplies for non-irrigation uses” in the Pinal AMA. Increased comprehensive planning and program efforts are needed to ensure a reliable and sustainable supply of water for municipal and industrial uses.
GROWING INDUSTRIAL USE
Groundwater mining by industrial users has increased rapidly and may continue to increase in the Pinal AMA. Industrial groundwater mining needs to be limited to an annual amount that is consistent with the need to preserve future water supplies for non-irrigated uses.
AUGMENTATION & RECHARGE
There is a need for regional recharge and recovery planning in the Pinal AMA to minimize the impacts of local problems, including lack of physical availability of groundwater, excessive water-level decline rates, land subsidence, and earth fissuring.
AMENDMENT OF PINAL AMA ASSURED WATER SUPPLY RULES
The Department has amended the Assured Water Supply (AWS) Rules for the Pinal AMA several times related to the requirement to be consistent with the goal of the AMA. In order to obtain an AWS determination, an applicant must prove five criteria: 1) that the water supply is physically, legally and continuously available for 100 years; 2) that the water supply is of adequate quality; 3) that the applicant has the financial capability to construct any necessary water infrastructure; 4) that the proposed uses of water are consistent with the AMA management plan; and 5) that the proposed uses are consistent with the AMA management goal. The AWS Rules allow a certain volume of groundwater to be used that is considered consistent with the AMA goal in each AMA. One component of how groundwater can be used consistent with the AMA goal is the creation of extinguishment credits. An extinguishment credit is an allowance for an AWS determination to pump additional groundwater based on the retirement of an existing grandfathered groundwater right in the AMA. Forming a strategy for the calculation and allocation of extinguishment credits which is consistent with the AMA goal has proven to be a long-lasting challenge.