• Active Management Area (AMA) Status: Designated as an AMA in January 2026 to protect against overpumping, this designation imposes mandatory groundwater measurement, reporting, and management plans, notes the Environmental Defense Fund.
• Location and Features: The basin is located in west-central Arizona, bordered by the Harquahala, Plomosa, and Harcuvar mountains. It is primarily rural but contains a large, concentrated area of agricultural activity southwest of Vicksburg, notes Arizona Department of Water Resources.
• Water Level Declines: The basin is classified as a “priority” area due to severe declines, with some wells showing drops of over 200 feet since the 1980s.
• Agricultural Impact: The area hosts heavy agricultural use, including large-scale alfalfa and jojoba farming, which creates significant drawdown (a “cone of depression”) in the groundwater table, according to the Arizona Department of Water Resources.
• Water Characteristics: Groundwater is found in both Quaternary alluvium and Tertiary deposits, with annual natural recharge estimated to be roughly 7,000 to 8,000 acre-feet, which is significantly less than recent pumping levels, research from FHSU Scholars Repository explains.
• Recently designated as an Active Management Area (AMA) by the Arizona Department of Water Resources in 2026. https://www.azwater.gov/designation-process-ranegras-plain-groundwater-basin-ama
• The designation was made due to concerns about groundwater levels and long-term sustainability.
• Future groundwater use in the basin will be subject to additional management and planning.

• Location: Spans western Maricopa, eastern La Paz, and southern Yavapai Counties, bounded by the Harcuvar Mountains to the north and Harquahala/Vulture Mountains to the south.
• Water Crisis: The basin is experiencing severe depletion, with water levels dropped up to 300 feet since the 1940s, primarily due to agriculture.
• Subsidence: Intense groundwater pumping has caused the land to sink over 4 feet in some areas since 1991, affecting towns like Salome, Wenden, and Aguila.

• Location: Located near Tonopah, Arizona, it is bounded by the Harquahala, Big Horn, Eagletail, and Little Harquahala mountains.
• Purpose: It manages areas with declining groundwater, limiting new irrigation on land not cultivated in the five years prior to 1981.
• Water Usage: Agriculture is the primary water user, though the region is a source for transporting water to more regulated areas, such as the Phoenix Active Management Area (AMA).

Drinking water
Many rural homes rely on private wells.

Agriculture
Farms depend on groundwater irrigation.

Economic development
Businesses and industry require reliable water supplies.

Community resilience
Groundwater provides a buffer when surface water supplies fluctuate.

Aquifers gain water through a process called recharge, which occurs when water moves downward into underground formations.

Recharge sources can include:

• Rainfall soaking into the soil
• Floodwaters from washes and rivers
• Irrigation return flows
• Managed recharge projects

In arid desert environments like La Paz County, natural recharge happens slowly, which is why long-term water planning is important.

https://www.amwua.org/blog/groundwater-the-growing-challenges