Arizona to study 2 ideas to add to its water supply

An Arizona state agency’s governing board unanimously agreed Wednesday to spend more than $7 million total to conduct detailed analyses of the two projects’ costs, potential environmental impacts and possible issues with getting them permitted, among other things.

But while the projects are officially classified as water importation schemes, in reality Arizona probably wouldn’t import any of the drinking water created by these projects, although a possibility exists that one would involve some importation.

Instead, the plan would be for Arizona to exchange its rights to water created for these projects with various entities in California for some of their Colorado River supplies.

While the projects’ developer, Epcor, acknowledged that such an exchange proposal poses risks because of declining Colorado River supplies, at the same time California has rights to far more river water and much of it has a higher legal priority than Arizona’s supplies during river shortages.

The Water Infrastructure Finance Authority of Arizona board approved financing these studies as part of a complex, three-stage process it’s created to select one or more projects to increase Arizona’s water supplies.

In the coming months, its board will review five other proposed importation projects to determine how many should get state funding to conduct more detailed studies of their costs and relative merits.

Three of them involve building new desalination plants in other states and Mexico. Those projects would also include provisions for Arizona to exchange the rights to the desalted water for other entities' Colorado River water rights.

Over time, each project selected for further review will go through more detailed analyses as they proceed through each of the three stages of review.

Ted Cooke, who chairs the board’s long-term water augmentation committee, said he doesn’t know exactly how far off it will be before the board makes final decisions to select projects for actual construction. But the two Epcor projects have a total period for reviews of up to 26 months.

Technical, environmental, cost and financial issues will be reviewed before decisions are made on whether to build an individual project.

But the agency has set a goal of starting to deliver 100,000 to 500,000 acre-feet a year — one to five times Tucson Water’s annual residential customer demand — of augmented water in 10 to 15 years, authority director Chelsea McGuire said at a media briefing after Wednesday’s board meeting.

Specifically, Epcor’s proposed projects include:

• A plan to store underground 100,000 acre-feet a year in three constructed groundwater recharge basins. The water would come from various river water supplies in the Sacramento and San Joaquin valleys in central and northern California.

• A plan to treat to drinking quality wastewater from the South Bay International Wastewater Treatment Plant.at San Diego’s south end, near the Mexican border. The company might also build a pipeline to take the wastewater directly to Arizona if that’s determined to be a feasible idea.

This plan also might be combined with a separate project to take desalinated water from a planned Baja California desalination plant. If that happens, the entire project would produce 225,000 acre-feet a year, bringing the two projects’ combined water supply to more than 300,000 acre-feet a year.

Speaking of the groundwater storage project, Kirstie Craig of Epcor told the board the water stored could be used to benefit local water users, which she said would make the project a "win-win."

The project would require building a wide array of water infrastructure elements: recharge basins, canals to carry the surface water to the basins, structures to divert the water from canals to the basins, and wells to recover the recharged water when it's needed.

As for the exchange of Colorado River water, Epcor listed potential partners for the exchange as the Metropolitan Water District and the Imperial, Palo Verde and Coachella Irrigation districts in Southern California. 

But Craig also listed a number of potential risk factors for the project. They include the possibility that Epcor couldn't secure a California partner to carry out the Colorado River water exchange and that permitting and regulatory issues would bog the project down.

There's also the risk that existing canals and pipelines in the area of the project wouldn't have enough capacity to carry the water to recharge basins and that local aquifers wouldn't have the capacity to store all the recharged water, Epcor said.

Of all the risks, Cooke said the risk of being unable to find a water exchange partner plus failure to find customers for the water would be "make or break. If you don't have those two, nothing else matters."

The wastewater treatment project would involve converting the existing South Bay plant to one that can either directly or indirectly treat wastewater for drinking. Indirect treatment would recharge wastewater into the aquifer, then pump the wastewater out after the aquifer has naturally removed  the contaminants. 

Another approach could be to build a pipeline to take less treated wastewater from Tijuana to the Yuma area, where a plant could be built to provide the final treatment to drinking quality, Epcor said.

Besides the risks to the project from declining Colorado River supplies, other risks include whether the project water will be affordable to customers, whether adequate electric power exists in the area of the treatment plant, and whether the public will accept the idea of drinking heavily treated wastewater, Epcor said.

During the media briefing after Wednesday's meeting, Cooke addressed the question of why the process to approve these projects is being split into so many parts.

"We're doing that so we can stop early enough before we’ve spent a lot of money to determine that something is not feasible — giving ourselves an opportunity to have an off ramp," Cooke said.

He noted that the city of Corpus Christi, Texas, took six years planning and studying a proposed desalination plant before ultimately abandoning it as not feasible in 2024.

"We're not going to take six years on an unsuccessful project. We may take six years to do a successful project," he said.