Water Study Digs for Data, Solutions

Arizona’s water supplies are coming under greater scrutiny, with a high likelihood of a first-tier shortage being declared on the Colorado River in August due to the historic drought. If that happens, the state will lose more than 500,000 acre-feet of its annual allocation.

Pinal County farmers are the first major group of Arizona water users in line to have their supply of river water severely cut under the shortage, and are scheduled to lose all of it by 2030. As a result, some agricultural users are drilling wells to get water for their crops.

This has major implications for the area’s groundwater table, which already supports most residential and industrial users and is projected to not be able to meet the demand from the county’s rapid population and economic growth over the next century.


GROUNDWATER BASIN STUDY

A Pinal Partnership-led study of the groundwater basin is less than a year away from its expected completion, which will include recommendations on how to conserve supplies as well as possible new sources.

Jake Lenderking of Global Water Inc., one of the basin study’s managers, said he’s not looking toward a time when western Pinal is expected to simply run out of water.

“I don’t anticipate we’re actually going to run out of it, the idea is to make it more sustainable. We do see aquifer levels dropping, potentially pretty deep in some areas. I think it could have some impacts, but I wouldn’t say we’re going to run out of water,” he said.

The in-depth analysis, funded by a $1.86 million grant from the U.S. Bureau of Reclamation (BOR), is compiling data on the groundwater table below Maricopa and Stanfield in the west and Florence and Coolidge in the east, covering about 1,575 square miles.

The study, known as the Eloy and Maricopa-Stanfield Basin Study, is running current and updated data about the groundwater table through several scenarios based on different levels of population growth, agricultural activity, and climate change through the year 2060, while looking at strategies for conservation and possible new sources of water.

Launched in November 2018, the study is set to wrap up in May 2022.

“It has been a lengthy process but, very thorough. I am confident that it will help us understand and lead water management in Pinal County for years to come,” Casa Grande Mayor Craig McFarland said.

How much more development there will be is in question because the Arizona Department of Water Resources (ADWR) in late 2019 declared a moratorium on new certificates of 100-year water supply for projects seeking approval in the county. Projections show an 8.1 million acre-foot shortfall of “unmet demand” for currently approved projects through the year 2115.

Lenderking is senior vice president of water resources and legislative affairs for Global Water, the water utility serving the City of Maricopa and other parts of Pinal County.

Global Water and BOR are part of the team Pinal Partnership assembled to donate time and resources to the study, along with the Arizona Department of Water Resources, Central Arizona Project, Pinal County, the cities of Casa Grande, and Eloy, and other entities.

The groundwater table is declining, but there’s considerable variation within the broad area covered by the study.

Under the study’s hottest and driest climate assumptions with the highest growth projections, the water table could rise by 100 to 200 feet in one area just west of Casa Grande where water recharge is taking place, but within the city and areas just to the east could fall by 300 to 700 feet. Areas south of Eloy could see a similar precipitous drop, while Maricopa, Coolidge, and Florence are expected to see a drop of about 100 feet.

SEARCH FOR ANSWERS

Lenderking says the study’s stakeholders — all 60 or so members of the study team — are now looking into potential conservation and mitigation strategies to relieve some pressure on the groundwater table by reducing current usage or bringing more water into the area.

Conservation measures are being embraced by many residents and public agencies through xeriscaping and other methods, but more will have to come into play, including increased use of effluent for nonpotable uses, recharge, and potentially potable use.

New sources that could be studied include water sales from Native American tribes or other owners, desalinization of river water, and even what Lenderking calls “Hail Mary” concepts like importing Mississippi River floodwater.

For more information about the Eloy and Maricopa-Stanfield Basin Study, including background documents and meeting summaries, visit www.pinalpartnership.com/ems-basin-study