Brackish Buffer

Across the American Southwest, water scarcity has become an immediate constraint on growth and resilience. Prolonged drought, declining river flows and overstressed aquifers are forcing states to rethink how they secure and manage reliable water supplies.

New Mexico is one state sitting at the center of this challenge. Surface water is increasingly unreliable, groundwater resources are under pressure, and legal and interstate obligations further limit flexibility. Traditional freshwater sources alone can no longer meet growing demand.

In response, New Mexico is taking a step it has never taken before: systematically exploring deep brackish groundwater as a supplemental water supply.

Brackish groundwater, which is saltier than freshwater but less saline than seawater, has emerged as a promising option. It can be treated through reverse osmosis for potable water for humans and irrigation for agricultural crops.

Through the state’s largest investment to date in brackish water exploration and development, WSP is working with the New Mexico Environment Department to determine if underground brackish groundwater can help stabilize precious freshwater supplies.

“Brackish water isn’t a magic bullet, but it can provide an important buffer while longer‑term solutions are worked out,” said Jeffrey Samson, PE, assistant vice president of civil engineering, WSP in the U.S. and project manager. “That’s what this project is about.”

New Mexico’s water challenges are shaped by a complex mix of climate conditions, legal obligations and competing demands. Extended drought has reduced flows in major river systems, while interstate delivery requirements under the Rio Grande Compact and ongoing settlements with tribal communities further constrain supply.

This marks the first time New Mexico has undertaken a coordinated, statewide effort to evaluate brackish groundwater, from exploration and aquifer testing through treatment feasibility and long‑term planning.

It’s not an easy solution. But when you look at water rights, population growth and what’s happening with major river systems in the West, state leaders are seriously considering this option.

Brackish groundwater is found throughout New Mexico, often in deep, undeveloped aquifers. Unlike freshwater sources, brackish water can potentially be used without directly competing with municipal or agricultural supplies, if responsibly extracted and treated.

Brackish water offers a practical, near-term buffer, supporting communities and economic activity as the state rebalances its water portfolio.

New Mexico is not alone in exploring unconventional water sources. Other water-stressed states in the Southwest, particularly Texas, are further along in developing brackish groundwater as part of their water portfolios.

Over two decades, Texas has progressed from pilot projects to broader implementation, with dozens of inland desalination facilities supplying brackish groundwater to communities across the state. The world’s largest inland desalination plant sits just across the New Mexico border in El Paso, Texas. Experience gained has refined approaches to aquifer testing, materials selection, treatment design, cost control and brine management, informing projects throughout the region.

While New Mexico’s geology, regulatory framework and water-rights landscape are distinct, progress elsewhere demonstrates that brackish groundwater can move from concept to reliable supply.

For New Mexico, this project represents an important first step.

Our work is centered initially on the Middle Rio Grande Basin, which serves a large share of New Mexico’s population and water users and is under significant stress.

The project’s goals are straightforward but technically complex:

• determine how much brackish groundwater is available,
• understand its quality, and
• assess whether developing the resource could impact freshwater aquifers.

The current phase is exploratory and analytical, with no construction at this stage.

“They’ve identified a potential source, but they don’t yet know the quantity, the quality or whether developing it could impact freshwater resources,” Samson said. “This study will answer those questions so informed decisions can be made.”

Combining hydrogeologic exploration, aquifer testing and treatment feasibility analysis will help the state determine whether brackish groundwater be developed responsibly as part of its water strategy.

This effort is distinguished by an end-to-end approach that integrates expertise across hydrogeology, water treatment, regulatory strategy, stakeholder engagement and economics.

The work begins with advanced geophysical analysis and targeted drilling to characterize deep aquifers, followed by evaluation of treatment options based on actual water chemistry. Brackish water quality can vary widely, requiring tailored solutions.

Equally important is planning for waste and brine management. Treating brackish water produces concentrated byproducts that must meet environmental and regulatory requirements. The plan has to work from both an environmental and a sustainability standpoint.

Addressing these challenges early is essential to determine whether a project is feasible in the long term.

In desalination and brackish water treatment, innovation is often associated with new membranes or emerging processes. While technology matters, innovation also comes from system design, material selection, facility configuration and project delivery.

“We don’t innovate by inventing new treatment technologies,” said Tom Howell, CEng, principal process engineer, WSP in the U.S. “Our innovation lies in how we integrate expertise across whole of project life — from project inception and sequencing through exploration and investigation, treatment process selection, optimization of infrastructure layout and construction methodology, and managing regulatory strategy to deliver efficient, sustainable solutions that work for both today’s requirements and long-term community expectations."

By emphasizing constructability and lifecycle cost control, the team is helping the state evaluate practical, defensible options rather than forcing a single solution.

Water development in New Mexico is shaped by people, place and history. New water sources must be evaluated through a technical lens, as well as regulatory, cultural and community perspectives.

Work requires close coordination with state agencies, municipalities, tribal governments and other stakeholders. Transparent engagement is essential, given the sensitivities surrounding water rights and longstanding resource challenges.

The goal is to support informed decision making and build trust, not to predetermine outcomes.

While the current focus is the Middle Rio Grande, the broader ambition is statewide. The framework being developed combines exploration, treatment feasibility, regulatory insight and stakeholder engagement. It is intended to be repeatable across other basins.

Brackish groundwater may become an important part of New Mexico’s diversified water portfolio. This effort is helping the state explore that option responsibly, grounded in science and long-term thinking.

“Demand has reached a point where states are realizing they can’t ignore it anymore,” Samson said.

As a bridge to greater water resilience, brackish water development is part of a practical foundation supporting the journey ahead.