Water Providers Work to Recharge Pinal County Aquifer

As Pinal County leaders search for solutions to a projected groundwater shortage for new development, utility providers are turning their efforts to bolstering the aquifer by “recharging” it with new or recycled water. 

Arizona Water Company began channeling Central Arizona Project water into two new basins on the southwest edge of Coolidge in January. The basins are designed to funnel water down into the soil, through the soil and into the groundwater table, where it can replenish the aquifer for current users and potentially supply future growth. 

Mark Kieren, general manager of the Coolidge and Casa Grande water systems for Arizona Water Company, said the company expects to be able to send 2,000 acre-feet of water annually into the aquifer through the two basins. 

An acre-foot is generally defined as the amount of water needed to supply a suburban family household for a year, though usage varies widely. 

Arizona Water has the right to use nearly 11,000 acre-feet of water from the Colorado River every year in the Coolidge area, and studied the alternatives for transporting and using that water, Kieren said. 

The idea of building a water treatment plant was considered but proved too costly to pursue, so in 2014 Arizona Water decided to pursue the recharge option for its allocation. 

“That was the choice we made back then, and we’ve been working toward that ever since. And in the last year and a half we were able to put this project together and pull it off, and it’s actually functioning right now,” he said. 

The cost of building the initial recharge facility is coming in at nearly $8 million, the largest single expense being the turnout and infrastructure to channel water from the Central Arizona Project system into the basins. 

Because the basins are so new they haven’t been fully filled yet, but early indications are they’re functioning well, Kieren said. 

Once they’re full, the level of the water in the basins will be used to measure how quickly the water is being sent into the aquifer, he said. 

Arizona Water’s longer-range plans call for three more basins on the 10 acres set aside for the recharge project, but Kieren said the construction timeline will be tied to the complex matter of finding enough water to meet the needs of future Pinal County development. 

“We’re trying to stay ahead of it, and we’re trying to take advantage of this water that’s available to us through this CAP allocation, that’s our responsibility. It turned out pretty nice, it’s a really nice facility and everything’s gone pretty well,” he said.

The Arizona Department of Water Resources determined last year that projected future growth in Pinal County would create 8 million acre-feet of unmet needs over the next 100 years. An ad-hoc committee headed by County Supervisor Steve Miller and state Rep. David Cook is meeting to look for potential water supplies and address other issues.

In Maricopa, water and wastewater service provider Global Water is in the planning and permitting stages for a similar recharge facility, which President and CEO Ron Fleming said will hopefully come online in 2021. 

He said the company focuses on using treated wastewater for nonpotable uses such as landscaping, but typically has excess amounts of it during the cooler winter months when demand is lower, so that excess will go into the recharge basins. 

“We’ll be recharging right into the area where we’re withdrawing from for use, so right back into the aquifer,” he said. 

Global Water has also signed an agreement, subject to Arizona Corporation Commission approval, to serve the Inland Port Arizona between Eloy and Coolidge, including the site of the planned Nikola Motor Company manufacturing facility. Fleming said the company plans to build recharge facilities for the new utility being formed there. 

Photo: Arizona Water Company built a 48-inch wide slidegate with a span of up to 19 feet on the Central Arizona Project canal to obtain the water for the recharge basins. It is currently being manually operated but its automatic controls will soon come online. Photo courtesy of Arizona Water Company.