KRWG

Desalination Plant Could Supply Santa Teresa With Water

Jan 29, 2019

There’s a water shortage in Southern New Mexico. The Rio Grande is increasingly dry. Farmers are forced to pump groundwater from the Mesilla Bolson. But there's another, untapped source of water in the aquifer: brackish water. In the coming years, that salty water could get put to use.

 


A few decades ago, Santa Teresa was mostly empty desert.

“Well I got here in 1991,” says Jerry Pacheco, president of the Border Industrial Association. “There were four buildings. There was no port of entry.”

Since Pacheco moved to the region, it’s changed dramatically. There’s a bustling port of entry and four large industrial parks.

“Our little corner of the state accounts for about 53% of New Mexico’s total global exports,” says Pacheco. “So we’ve gone from oblivion to a major player.”

But in order to sustain that growth, Santa Teresa needs water. Not a ton, Pacheco says. He consciously tries to recruit businesses that don’t use a lot of water.

“We have right next to us a steel plant,” he says, motioning next door to his office. “They distribute steel coil to Mexico. They slit the steel. There’s no water used in that process.”

But those businesses still employ thousands of people “turning on the sink or flushing the toilet or what have you,” he says.

That’s where brackish water comes in.

“Brackish water is a source of water that has not been historically utilized at all,” says KC Carroll, with the Water Science and Management program at New Mexico State University.

“So if we were to start using brackish water, it would essentially be an alternative and a yet a new water resource for this part of the world.”

Carroll is part of a team that’s designing a pilot desalination plant, which could transform brackish water from the Mesilla Bolson into fresh, potable water - essentially by pumping it through a membrane to get rid of salt and bacteria.

The idea is to build the plant in Santa Teresa, and use that newly desalinated water to support industrial growth, potentially on both sides of the border.

But why Santa Teresa, when so much of New Mexico could use the extra water? There are a few key reasons.

Phil King is in the Civil Engineering department at NMSU. He’s one of the partners of the desalination project.

“For one thing, desalinated water is a lot more expensive than a lot of the traditional sources of water that we’ve been using in this area and frankly, a lot of the residential water users would have trouble with the price tag,” King says.

“But in Santa Teresa, particularly where they’re looking at developing the industrial park, that brings a lot of businesses in there for whom the cost of water is almost irrelevant in their larger budget.”

And those business bring significant money to the state. But the location is also crucial.

“We have identified a place that will be hydrologically isolated from the Rio Grande river system,” says King.

That’s important, because New Mexico and Texas are caught up in litigation about sharing the Rio Grande.

“So if we got a little over to the west, the geology gives us a sort of buffer between the brackish groundwater that we would be extracting and the surface water system of the Rio Grande,” he says.

In other words, this water source is insulated from the ongoing dispute between the two states.

Right now, King and his colleagues are still studying the feasibility of the project, including how much it would cost.

Pei Xu is working on the desalination technology. Like King, she’s in the Civil Engineering department at NMSU. She says her team is still figuring out some environmental concerns, like what to do with the concentrated salt that gets left behind during the desalination process.

“The concentrated disposal is very challenging,” Xu says. “Especially for inland facilities because we have limited options for the brine disposal.”

You can’t just inject it back into the ocean, like with a seawater desalination plant.

Phil King says it could be years before the plant comes online.

“Optimistic I would say 5 years, pessimistic I would say 15 years,” he estimates.

And he stresses that alternative water sources, like desalinated brackish water, barely make a dent in the larger problem.

“It’s almost niche water that you can use for something like an industrial park,” King says. “But the persistent shortage that we’re seeing of snowmelt runoff coming down from Southern Colorado and Northern New Mexico is short by hundreds of thousands of acre feet. When we talk about desal in Santa Teresa, we’re talking about a very few thousand acre feet. So it’s a very valuable thing, we definitely have to look at and develop it, but it’s not going to fix what’s wrong with our hydrologic system.”

That, King says, is climate change. And tackling that requires much more than a desalination plant.