Unlocking Arizona’s Groundwater: Essential Insights for Smart Decision-Making

Groundwater concerns have escalated in Arizona as the ongoing Colorado River shortage heightens the need to safeguard this critical resource. In central Arizona, cities are reevaluating groundwater management principles that have remained unchanged for three decades. Concurrently, rural communities are engaging in discussions focused on long-term groundwater sustainability.

Groundwater refers to water stored in the permeable layers of sand, gravel, and rock beneath the Earth’s surface. It inhabits the spaces within these materials similarly to how water occupies a sponge.

This resource is vital, constituting 41% of Arizona’s water supply, which surpasses both surface water and water sourced from the Colorado River.

However, groundwater is a finite resource. The majority of Arizona’s groundwater has existed for tens of thousands of years, and its natural replenishment through precipitation is minimal. This has led to it being classified as “fossil” groundwater, largely irreplaceable in the short term.

Effective management of groundwater resources is crucial. Excessive withdrawal can result in permanent depletion, akin to depleting a savings account. Rapid extraction leads to aquifer compaction, where land can subside and fissures may develop. Once compaction occurs, the aquifer’s ability to store water diminishes permanently.

Groundwater does not adhere to property lines, creating a common-pool resource situation. Without proper regulation, any landowner can drill a well, thereby negatively impacting neighboring landowners. Those with deeper wells and larger pumps often monopolize resources, jeopardizing communal needs.

Currently, only aquifers within Active Management Areas, where usage is restricted and supply replenished, see rising groundwater levels. Moreover, with the reduction in Colorado River allocations, the water necessary for replenishing these aquifers is jeopardized.

Arizona’s economic vitality hinges on reliable water supply for its homes and businesses. Sustainable management of this resource is essential for future development.

Despite the clear need for management, resistance exists due to immediate economic pressures. It is often more convenient to deplete groundwater rather than adopt long-term sustainability practices.

Lawmakers are urged to consider several critical questions when assessing proposed changes to groundwater regulations:

• Will the proposed change result in increased long-term groundwater pumping?
• Is the change “net-zero” regarding aquifer impacts, meaning does any increase in groundwater withdrawal correspond with an equal replenishment?
• What assurance exists that any short-term pumping increases can be compensated with future replenishment?
• Does this proposed change shift costs onto the general populace while benefiting special interest groups?
• Does it create uncertainty about Arizona’s assured water supply program, potentially endangering consumer protections against water scarcity?
• Ultimately, does the change diminish opportunities for future generations in Arizona?