Phoenix AMA Model is an important tool for proactively managing our groundwater and ensuring responsible growth

Published Jun 06, 2023

The recently released Phoenix AMA Groundwater Model has generated much attention and conversation. While it's an important step forward to continue our long history of securing and strengthening our water supplies, it's imperative to emphasize these are only projections for the next 100 years and do not mean we do not have enough water or will run out of water.

The model is a tool to help ensure we manage our groundwater supplies responsibly so that our communities can continue to thrive and prosper. What this model projected is that there would be a 4% shortfall in groundwater supplies to meet anticipated demands over the next 100 years if no changes were made - an outcome that was not unexpected. Now due to this projected shortfall, the Arizona Department of Water Resources (ADWR) will not issue any new Certificates of Assured Water Supply that rely solely on groundwater. These certificates allow residential developments to be constructed. However, certificates that rely on other supplies like surface water, imported water, reclaimed water, and long-term storage credits may still be approved.

While a pause on groundwater-dependent growth may sound alarming, ADWR has clarified that growth will continue in the Phoenix AMA across significant volumes of approved Certificates of Assured Water Supply within the service areas of water providers with a Designation of 100-year Assured Water Supply , and in the regions that are not solely reliant on groundwater, including the construction of 80,000 homes with Certificates of Assured Water Supply that have already been approved. This also means that growth will not be impacted in all ten AMWUA municipalities or other water providers with an Assured Water Supply Designation. To be designated, a provider must show they can meet all current water demands of their community and demands for development that has not yet occurred by proving they have water that meets all State and Federal water quality standards, and is physically and continuously available for the next 100 years. This 100-year timeframe exists on a rolling basis because each provider must apply for redesignation every fifteen years. The redesignation process ensures that their water sources and future projections are evaluated regularly. Certificates and Designations of Assured Water Supply are the foundation of Arizona's responsible water management, which is built on the simple principle: "Water first, then development." This principle guides water managers with growth planning to provide consumer protection and water resiliency for homebuyers, businesses, and communities.

As designated providers, the AMWUA cities have invested billions in water resources and infrastructure so that they do not solely rely on groundwater. Collectively they have built 30 water treatment plants to fully utilize surface water supplies delivered by CAP and SRP. In 2021, those surface water supplies represented 90% of their drinking water supplies - meaning groundwater accounts for a small percentage of the AMWUA cities' collective water portfolio. These significant investments, combined with long-term planning, have well-positioned the AMWUA cities to be resilient in the face of challenges and less susceptible to problems identified by the groundwater model. 

We are pleased that the Governor's Office has released the Phoenix AMA Groundwater Model. These projections provide a critical roadmap for all water providers in the Phoenix AMA, which is vital to our collective resiliency as desert communities. The Assured Water Supply Program is working as intended by ensuring water supplies are available before growth. This pause will allow our water leaders to develop innovative solutions to address this projected shortfall in groundwater availability so the Phoenix metropolitan area continues to grow responsibly. 

Safeguarding our groundwater supplies and sustaining our aquifers in the Phoenix AMA and across our state will benefit all of us and continue our long legacy of wise water stewardship. We cannot dodge or avoid the difficulty of grappling with groundwater issues, and we must make tough decisions and take bold action, which is precisely what this model will force us as a state to do. Ultimately, it's about living within our means and growing sensibly so communities can be resilient and not rely solely on a finite resource.

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For over 50 years, the Arizona Municipal Water Users Association has helped protect our member cities' ability to provide their communities with assured, safe, and sustainable water supplies. For more information, visit .