ADWR’s top hydrologists discuss the recently released Phoenix-area groundwater model

A big part of the current debate over homebuilding and groundwater supplies in metropolitan Phoenix involves a computer program released in 2023 by ADWR known as the numerical basin-scale groundwater flow model, or, simply the model, which found that over a period of 100 years, the Phoenix AMA would experience 3.6 million acre-feet of unmet demand for groundwater supplies, given current conditions.

The unmet demand finding has meant that, by law, ADWR no longer is approving home development in the Phoenix AMA that relies on groundwater as its permanent supply of water for those new homes.

The model’s impact on local discussions about growth in Arizona, particularly discussions involving homebuilding, has been significant.

On the one hand, it has prompted a serious examination of more renewable alternatives to the area’s decades-long reliance on groundwater for economic growth.

On the other hand, it recently has prompted a reactionary lawsuit against ADWR that, in part, challenges the very nature of scientific groundwater modeling as a check on the region’s reliance on groundwater mining.

ADWR’s Chief Hydrologist Ryan Mitchell and the Department’s modeling manager, Emily Lodolce, recently sat down with Arizona Water News to talk about the model and its implications.

Editor’s note: This is Part Two of a two-part series on the implications of the Phoenix AMA groundwater model. Part one delved into the importance of the 1980 Groundwater Management Act. It can be found here.