The Limited Role of Brackish Groundwater Desalination in Texas’ Future
Long term problems call for long term solutions.
In the decades to come, Texas will undoubtedly face grave challenges in maintaining its water supply.
The looming threats of climate change and population growth require long term solutions to what will soon be large-scale water shortages. Retaining our current supply through conservation and betting on semi-consistent rainfall is no longer enough; we have to begin producing more water than we could dream of possessing today if we want to ensure sustainability for future generations. But how can we produce more in the face of a warming climate and a booming population? The answer may be an unconventional solution: brackish groundwater desalination.
Brackish groundwater is generally considered to be any naturally occurring source of water that contains generous amounts of salt. It is thought of as saltier than freshwater, but not as salty as seawater. It requires extensive treatment in order to be used in everyday life, say for municipal or irrigational use. As you can see in Figure 1, Texas has a significant amount of brackish groundwater. The Innovative Technologies Team at the Texas Water Development Board estimates that there are 880 trillion gallons of brackish groundwater lying in Texas’ 30 designated aquifers. To give you an idea of how huge that is, it’s enough to maintain Texas’ current consumption for 150 years.
An Untapped Resource
Now despite the fact that it exists in huge quantities, why is the desalination of brackish groundwater important? It is for the most part, an untapped resource in a state where we have struggled to maintain consistent supplies. In the past decade, dozens of states across the U.S. have faced a decline in fresh and potable groundwater, which has raised significant concerns about the future availability of water for household consumption, as well as industrial and environmental needs.
Texas has been the victim of many severe droughts, a circumstance that has triggered legislative action. In 1957, the Texas Legislature formed the Texas Water Development Board. This organization was charged with the task of publishing and implementing a state water plan every 5 years. Each water plan outlines Texas’ estimated water consumption in the coming decades, and what the board plans to do to address an increase in consumption. The board’s most recent water plan was issued in 2012. This report noted that the most significant challenges Texas will face as a state are climate change and an increase in population. Figure 2 shows that Texas’ population will increase by more than 20 million by 2060, triggering an annual 2.6 trillion gallon water deficit.
The Tale of 2%
Many experts at the U.S. Geological Survey and txH2O magazine have called it the most promising option in the future of water planning; so how much of the 2012 State Water plan consists of brackish groundwater desalination? Looking at Figure 3, you may be as surprised as I was to learn that it constitutes only 2% of the statewide plan, despite the growing deficit.
The Development Board is operated by some of the most brilliant minds in water policy, so it begs the question of what is limiting the TWDB from utilizing an untouched resource. Cost is the largest concern in any desalination treatment. This bars us from making both ocean and brackish water significant contributors to our water supply. Both the cost of construction and production are considerations that must be made in a statewide plan. The price of a brackish water desalination plant can vary significantly depending on the infrastructure chosen for that specific plant, the location, and the production capacity. While the Lasara Plant was valued at $2 million and produces 1.2 million gallons per day, the larger Kay Bailey Hutchison Plant in El Paso was valued at $91 million and produces 27.5 million gallons per day. The price tag for construction is high, and the state also has to consider the production costs.
Another concern is waste management. Desalination is typically completed through the use of reverse osmosis, where a membrane separates the clean water from the salty byproduct. This byproduct is called concentrate. Concentrate not only includes salt, it also includes chemicals applied to the water during treatment. How the concentrate is disposed of depends on its composition. Less harmful concentrate can be released into surface water supplies such as streams, rivers or the ocean. More harmful concentrate is expensive to dispose of; construction costs on infrastructure like evaporation ponds and deep well injections can be pricey, and it takes time to appropriately determine their impact on the environment.
That brings us to a lack of research. Compared to other methods of delivering water to the public, brackish water desalination is a relatively new tactic. Studies are still being done to ensure plants are built in the most cost-effective way, while also avoiding any damage to surrounding areas and water supplies.
Despite these cons, with increased research and investment, brackish groundwater desalination could become our saving grace in the face of a booming population and a changing climate. Texas currently has 34 brackish groundwater desalination plants that produce over 73 million gallons of water per day. As more plants are built, experts are able to find more cost effective ways to design them, leading to a decline in both construction and production costs year after year. In 2012, TWDB found the average cost to produce 1,000 gallons of water through this method ranged from $1.25 to $2.60, which includes capital, operational and maintenance costs. Plants often improve their technology as funding becomes available, allowing them to produce more water and expand on an already blossoming development.
The biggest advantage associated with brackish water desalination is that it has the ability to increase our overall water supply. Over 96% of the 2012 State water plan’s proposals to address a deficit consist of conservation and the use of the limited amount of water we already have. Only 3–4% consists of strategies that increase our water supply to support a population that will nearly double within two decades. We have no other choice but to begin investing in strategies that provide us with a method to produce more water.
Texas [Water] Forever
The concerns surrounding the development of brackish groundwater desalination are warranted, but steps must be taken to increase our understanding of this method and design more cost-effective ways to enhance its benefits. This strategy also has the ability to provide both public and private investment opportunities. The government is always looking for private companies interested in investing in efforts to increase sustainability. Just this summer, the Bureau of Reclamation, the Interior Department and NOAA set out to increase private sector partnerships and enhance job creation, while also improving water supplies across the country.
Although Texas has been reluctant to chase federal funding for environmental endeavors, grants and assistance from USGS’ WaterSMART program would help many communities increase their local water supplies. While much of the board’s 2012 plan consists of dwindling surface water sources, my hope is that the 2017 plan will pursue more long lasting efforts to help Texas remain a front runner in agriculture and industry.