Well Water in Willcox Basin, Arizona

Cochise County · Population ~8,100 · Aquifer: Willcox Basin Alluvial Aquifer

Hardness: Hard to Very Hard

The Scale of the Crisis

The Willcox Basin is being drained at a staggering rate. The numbers tell the story:

ADWR Chief Hydrologist Ryan Mitchell presented data showing 5.7 million acre-feet of groundwater mined from storage between 1940 and 2015. Over 1,200 wells have been drilled or deepened in the last 14 years alone.

Since the 1950s, the ground surface has sunk as much as 12 feet. Using satellite data from 2017-2021, researcher Dr. Danielle Smilovsky found some areas sinking at rates of up to six inches per year. The Willcox Basin is currently experiencing the fastest land subsidence in Arizona.

Earth Fissures

Land subsidence from groundwater pumping doesn't just lower the surface — it cracks it open. Nearly 50 miles of earth fissures have been mapped in the Willcox Basin, creating chasms that can be dozens of feet deep and run for miles.

Earth fissures damage roads, pipelines, foundations, and — critically — well casings. A fissure that crosses your property can crack your well casing, allowing surface contaminants to enter the aquifer directly. It can also shift the ground enough to damage your home's foundation.

The Arizona Geological Survey maps known fissures, but new ones appear as subsidence continues. If you're in the basin, check the fissure maps and be aware that the ground beneath you is still moving.

The AMA Designation — December 2024

On December 19, 2024, ADWR Director designated the Willcox Groundwater Basin as Arizona's seventh Active Management Area — the first new AMA established since the original five were created by the 1980 Groundwater Management Act.

This was a historic action. In 2022, Cochise County voters had defeated a ballot measure to create an AMA. ADWR proceeded under statutory authority, citing the severity of the crisis.

What the AMA does:

• Existing water users can continue, but conservation requirements are imposed
• Irrigation is limited to acres legally irrigated in the five years before October 23, 2024
• New large-scale agricultural operations from out-of-state corporations are restricted
• Protects the 8,100+ people who depend on the basin

The AMA is a necessary step, but it cannot undo the damage already done. Subsidence is permanent — the compacted clay layers that held water will never re-expand.

What Willcox Basin Well Owners Face

Residents in the Willcox Basin are in a dire situation. There is no public water service in much of the basin — residents depend entirely on private wells. Many cannot afford the tens of thousands of dollars needed to deepen wells as water levels drop.

Governor Hobbs noted that residents' "wells are running dry, their homes are damaged by fissures in the earth, and their farms are barely able to get by."

Water quality concerns compound the supply crisis. The basin's groundwater has elevated fluoride and TDS, particularly in deeper zones. As wells are deepened to chase the falling water table, they encounter increasingly mineralized water.

If you're in the Willcox Basin: know your well depth, monitor your water level, and test your water quality. Things are changing — what was safe and sufficient last year may not be today. See our testing guide.