Water augmentation tested as Colorado River dwindles 

While the lack of groundwater regulation plagues rural Arizona, there are proposed ways to create a larger supply in the region without depending on dwindling amounts from the Colorado River and groundwater.

The Colorado River and local groundwater supplies around 40% of Arizona’s water. Lake Powell in northern Arizona and southern Utah is at record-low levels, as of Feb. 18. It is the lowest level it has been measured at since its construction in the 1960s.

Sarah Porter, director of the Kyl Center for Water Policy at Arizona State University, called the Colorado River crisis Arizona’s most imminent water problem. She said 80% of the state’s population gets its water from the Colorado River, especially through the Central Arizona Project (CAP), which is a canal that runs from western Arizona through Phoenix and south through Tucson.

She said 30% of Phoenix’s water comes from the Colorado River and is mixed with water from the Salt River Project (SRP) and groundwater, as Phoenix is part of an Active Management Area for groundwater.

“The Colorado River is a very important water supply,” Porter said. “It’s in really bad shape, and something has to be done very quickly.”

Porter said CAP has the last priority to Colorado River water and is “theoretically absent” from negotiations on who gets cut amid a shortage. She said Phoenix and Tucson’s water users, especially farmers, would be cut first. The area with senior priority over Colorado River water is the Imperial Irrigation District in California.

Rio Verde Foothills was one of the first populated areas to get cut off from a municipal water supply. Residents have resorted to using private wells and stored water resources, but that is not enough, according to Rep. Alexander Kolodin, R-Scottsdale.

“There’s only a few of us up there that have a stable enough source of water in their wells to actually share it,” Kolodin said. “They have to fill up the bathtubs … or they have to fill up the water containers – it’s just a terrible system.”

He sponsored HB2561, which passed the House Natural Resources and Water Committee 6-4, that would require on an emergency basis that Scottsdale restores water supplies to Rio Verde.

Kolodin said he wants a long-term water plan that does not involve water from the Colorado River because of inevitable shortages and water cuts.

The Scottsdale City Council voted unanimously earlier this week to adopt a resolution supporting a plan that would temporarily resume service providing water to the nearby Rio Verde community.

Water augmentation adds additional water supplies to the ones that already exist with the goal of being prepared for the future. Multiple augmentation methods have been tested throughout the state, but like regulation, there is no one-size-fits-all solution.

Juliet McKenna, principal hydrogeologist at Montgomery and Associates, said augmentation is “essential.” She said stormwater and flood management are ways to augment water supplies.

One of the more popular solutions is ocean desalination, but McKenna said this solution is too expensive and wasteful. She said ocean desalination would leave the brine extracted from the water in the open, and there is not a way to address what to do with the waste yet.

McKenna also said extracting sea water would negatively affect the marine environment of the Sea of Cortez, where the closest outlet to the Pacific Ocean is from Arizona. It would also require a multinational deal and would require an estimated 30 years to complete, according to Arizona State University’s Arizona Water Blueprint.

“I think the jury’s still out,” McKenna said.

She said groundwater protection can act as a “safety net” for when surface water supplies like the Colorado River are in a shortage, but they cannot be relied upon as they are “finite resources.”

There is an existing desalting plant in Yuma on the Colorado River, controlled by the Bureau of Reclamation and CAP. But it mainly sits idle due to how expensive it is to operate on a yearly basis. It has not been operational since test runs were done in 2010 and 2011.

Kolodin said this solution was a “pie in the sky” and it distracts from better solutions for the groundwater crisis.

Kolodin said his goal was to get an emergency bill passed to get water turned back onto Rio Verde for the short-term so that a long-term solution could be negotiated. Kolodin said his preferred long-term solution involves locally extracted brackish groundwater.

Brackish groundwater is groundwater with dissolved solids and saline in it. It can result from human interventions like wastewater recycling. According to Montgomery and Associates, 600 million acre-feet of brackish groundwater exists in Arizona.

“What I would like to see is the most achievable strategy to get more water in the system, which would be to desalinate Arizona’s brackish groundwater,” Kolodin said. “It’s way cheaper than … making a deal with Mexico because it’s on Arizona land.”

Kolodin introduced a bill last month, HB2323, that would allocate state money to fund long-term water supply projects centered on brackish groundwater supplies, but the bill appears to have stalled.

However, a similar bill introduced by Rep. Gail Griffin, R-Hereford, HB2217, appropriates $50,000 to the Arizona Department of Water Resources to update its studies on the availability of brackish groundwater across the state.

Brine disposal is still the main hurdle for brackish groundwater desalination plants. Disposing of it is expensive and can damage some habitats, according to the Arizona Water Blueprint. The blueprint says cost-effective brine disposal and management are difficult, if not “highly improbable.”

In an email, Porter said extracting and desalinating brackish groundwater is a viable solution in some places, but it is only a limited solution.

“Treating brackish groundwater is much more expensive than treating regular groundwater or surface water, and, as with other groundwater supplies, brackish groundwater is non-renewing, so growing cities on it leaves those communities with the problem of where to find water once the groundwater is used up,” Porter said in the email.

Other than desalination of either groundwater or ocean water, there are surface water augmentation efforts, including heightening existing dams, importing groundwater from other areas of the state to larger cities, and connecting water from SRP and CAP, but most of these are proposals.

Kolodin said the problem of finding an augmentation method is urgent.

“We’re getting slowly cut off from the Colorado River. And someday soon it’s going to be so slow that Arizona is not going to get Colorado River water,” he said. “We need to get more water in the system.”