2024 Updates to the Phoenix Active Management Area Groundwater Model
In accordance with an ADWR statement delivered at a Governor's Water Policy Council meeting on June 18, 2024, the Department has updated its Phoenix Active Management Area Groundwater model to include new information such as updated well-pumping locations. As a result, the Department is now releasing an updated version of that model which applicants are encouraged to use when applying for an Assured Water Supply determination.
Following below is an outline of key elements to be found in the model update.
- ADWR has amended the model to reflect updated reported well pumping, reasonable well movement requests by applicants and/or well owners, and technical corrections identified by ADWR and applicants since the initial release in June 2023.
- The amended model reflects ADWR’s policy of accepting reasonable well movements by the applicant and/or the well owner. ADWR has consistently communicated this policy in the Governor’s Water Policy Council and in other forums.
- Exceedances of the 1,000-foot depth-to-water limit still exist.
- While unmet demand has been reduced due to well movement, unmet demand still exists in the protected sectors. Unmet demand has gone up in the Designation of Assured Water supply, Industrial, and Agricultural sectors.
- Unmet demand has shifted from wells in the Analysis and Certificate sectors to wells in other sectors.
- Where unmet demand is reduced, additional water is pumped from the aquifer, drawing down the aquifer by mining the resource.
- ADWR will continue to make model and projection updates on an annual basis going forward.
- The 2024 model update does not support the issuance of Assured Water Supply determinations based on groundwater.
- A memo describing the 2024 model update is available here.
2023 Phoenix Model Release
After considerable data analysis and review, the Arizona Department of Water Resources has completed work on its new model of groundwater conditions in the Phoenix Active Management Area (AMA), a region of south-central Arizona encompassing 5,646 square miles and, with 4.6 million residents, the most densely populated area in the state.
The results of the numerical basin-scale groundwater flow model projection show that over a period of 100 years, the Phoenix AMA will experience 4.86 million acre-feet (maf) of unmet demand for groundwater supplies, given current conditions. The term “unmet demand” refers to the amount of groundwater usage that is simulated to remain unfulfilled as a result of wells running dry in the model. To show the physical availability of groundwater under the Assured Water Supply (AWS) program, existing and assured water supplies need to be fully met.
In keeping with these findings of unmet demand, the State will not approve new determinations of Assured Water Supply within the Phoenix AMA based on groundwater supplies. Developments within existing Certificates or Designations of Assured Water Supply may continue, but communities or developers seeking new Assured Water Supply determinations will need to do so based on alternative water sources.
The constraints regarding the physical availability of groundwater are attributable to the cumulative results of decades of groundwater overdraft and the continued reliance on groundwater resources.
This Phoenix AMA model is the most comprehensive, basin-scale numerical groundwater model developed for an AMA in the state of Arizona.
Since the implementation of Arizona's Groundwater Management Act of 1980, the objective of AMAs has remained consistent: to encourage the utilization of alternative sources for new development in order to reduce reliance on groundwater.
The new Phoenix AMA model shows that the primary goal of the 1980 Act is largely being met: existing homeowners are protected and will continue to receive their water deliveries into the future. The AWS program is working as intended – as a consumer-protection program - to ensure water supplies are available in advance of growth.
Documents
2024
2023