Groundwater is a finite resource that must be used wisely

This year commemorates the 45th anniversary of the landmark 1980 Groundwater Management Act, a crucial piece of legislation that established guidelines for sustainable groundwater use in Arizona. In conjunction with this milestone, we are also observing National Groundwater Awareness Week, an annual campaign to educate the public about the significance of groundwater resources. These two events offer an opportunity to provide insight into this water source and emphasize the critical importance of protecting our groundwater, which is vital for ensuring long-term water security and the well-being of communities across Arizona.

What is groundwater and why is it important?

Groundwater is an invaluable resource that is not typically thought about because we don’t see it like surface water, such as rivers and lakes. The only way to access this water is by pumping it through wells, much like using a straw to sip from a glass.

Groundwater is a finite resource that requires careful management. While it can be replenished through the natural water cycle, this process occurs very slowly. As a result, the total amount of groundwater available in any specific area is limited. If groundwater is extracted at a rate that surpasses its natural recharge, it can lead to depletion. To ensure its availability for future generations, it is crucial to manage groundwater use wisely.

How does Arizona protect groundwater?

In the 1950s, about 70 percent of the water used in Arizona came from groundwater. The recognition of our limited groundwater supply led to essential long-term planning and regulations, resulting in the enactment of the 1980 Groundwater Management Act (GMA) . With this came investments into numerous urban areas across our state to improve and diversify our water sources.

As part of the 1980 GMA, municipal water providers, including the ten AMWUA cities, invested billions in water resources and infrastructure, allowing them to diversify beyond groundwater reliance and achieve a 100-year Assured Water Supply Designation. Collectively, they constructed 30 water treatment plants to leverage surface water supplies from the Salt and Verde Rivers (SRP) and the Colorado River (CAP), significantly diminishing their dependence on groundwater. Nevertheless, groundwater continues to serve as an essential backup source, particularly during shortages of surface water supplies.

Although groundwater use across the state has decreased to 40 percent, it remains a crucial water source in Arizona, especially in some rural areas where it is the sole water supply. This highlights the importance of managing this resource now and in the future.

What is the current state of our groundwater and what is being done to further protect it?

The Phoenix area’s groundwater entered the national spotlight when the Arizona Department of Water Resources released its groundwater model of the Phoenix Valley. The model showed that over the next 100 years, the projected demand compared to available supplies would result in a shortfall of 3.6 million acre-feet. It also showed that the groundwater level is expected to decline by an average of 185 feet compared to a drop of 92 feet in the previous 100 years. This can create problems that range from land subsidence to poorer water quality.  Per our State’s 100-year Assured Water Supply Program, the projected deficit resulted in the halting of the development of new subdivisions that would rely solely on groundwater. 

This strong commitment to managing our groundwater, despite its impact on near-term developments, starkly contrasts with other areas of the country that are only now grappling with declining aquifers. It demonstrates that our 100-Year Assured Water Supply Program is working as intended by ensuring that water supplies are available before growth occurs – water first, then development.

While ensuring that we do not deplete our aquifer, the current status of our groundwater should also be motivation to develop innovative water solutions that include water policies and augmentation efforts. Initial efforts are underway, including adopting an Alternative Path of Designation (ADAWS) , which will allow undesignated providers to obtain a designation. Additionally, some municipalities are pursuing Advanced Water Purification (AWP) , and a stakeholder group is working with SRP to expand the storage capacity of Bartlett Dam. However, since there is not one silver bullet, much greater concerted action is needed to develop new water resources if we are to sustain our finite groundwater and balance responsible growth.      

Why does groundwater protection matter to the AMWUA cities?

The AMWUA cities understand that water security is the foundation of vibrant communities. They recognize that a robust economy depends on reliable water resources to meet the diverse needs of residents and businesses. They have invested billions of dollars to utilize surface water and significantly reduce their groundwater use.  

However, as municipal water providers expect a significant decrease in their supply of Colorado River water after 2026, they will need to offset those reductions. Since new supplies are not readily available, they may need to recover water stored underground and pump groundwater set aside in their Assured Water Supply Designations. This comes at the same time as the Phoenix-area aquifer is stressed. Therefore, the AMWUA cities recognize that failing to protect the near and long-term health of the aquifer could jeopardize their ability to meet the needs of current residents and businesses. This is why they are adamant about upholding the 100-year Assured Water Supply Program and only support new policies that protect our local aquifer.

While we acknowledge that the Groundwater Management Act was significant legislation, the need to continue to address groundwater issues in our state only grows, especially as we prepare reductions in water from the Colorado River, which will likely lead to increased groundwater use in Arizona. This highlights the importance of protecting our groundwater supplies and sustaining our aquifers in the Phoenix metro area and across the state. It upholds our long-standing tradition of responsible water stewardship. We cannot overlook the challenges associated with groundwater issues; instead, we must make difficult choices and take decisive actions. Ultimately, it’s about living within our means and growing sensibly, ensuring that our communities remain resilient and do not solely rely on a precious but limited resource.

For 55 years, the Arizona Municipal Water Users Association has worked to protect our member cities' ability to provide assured, safe, and sustainable water supplies to their communities. For more water information, visit www.amwua.org .