Could desalination increase our supply of water?

Could desalination increase our supply of water?

The Brazos River Authority has teamed up to study the feasibility of regional seawater desalination.

Why? Because you and I can't drink saltwater, and there's a whole lot more saltwater than freshwater on this planet.

At its regularly scheduled, bimonthly meeting on March 25, 2024, the BRA's Board of Directors approved a memorandum of understanding with the Gulf Coast Water Authority and the Harris-Galveston Subsidence District to participate in a regional seawater desalination feasibility study. The study will be led by the GCWA and conducted in compliance with the U.S. Department of Interior Bureau of Reclamation. The BRA will be involved throughout the process, offering input, helping with data, and reviewing projects.

Desalination is, simply put, the process used to turn saltwater (from the Gulf Coast, for instance) into freshwater you can drink.

This study will determine the scale of desalination needed, select a site for a plant, prepare cost estimates, determine potential disposal sites of the concentrate that comes from the desalination process, and evaluate if the State could, in some way, help with funding, said Brad Brunett, BRA's lower and central basin region manager. The study could also determine if some of the freshwater stored in BRA reservoirs and currently earmarked for the lower areas of the basin could be replaced with desalinated water, providing more fresh water supply to the upper reaches of the Brazos River Basin. 

"Frankly, the benefit for BRA for this project is that if we have a large source of water being injected in the lower part of our basin in the future, obviously, we can keep more of our reservoir and surface water upstream for other growing parts of the basin," Brunett said. "It's something in concept that offers major benefits for us."

How does a project at the Gulf help water supply in the far north of the basin, say, Possum Kingdom Lake? The 11 reservoirs in the BRA Water Supply System work together to meet the needs of the entire basin. If those closest to the coast need additional water to meet supply demands, for instance, during a drought, water can be released from an upstream reservoir. If additional water is created by desalination and available at the Gulf, that upstream request might not exist, keeping more water in those upstream reservoirs.

"The reason it's not been done here is not because of the technology but because the cost of desalinating seawater historically has been quite a bit higher than surface water and groundwater," Brunett said.

It's not a modern concept, but it is a complicated and expensive one.

The State of Texas does not yet have an operational seawater desalination plant for municipal purposes, according to the Texas Water Development Board. Seawater desalination is one of the many tools in the State's long-term water supply toolbox, according to the TWDB. Costs and location will affect how and if desalination will replace, supplement or complement other water resources.

The Gulf Coast Water Authority (GCWA) is one of the BRA's largest and oldest raw water customers, contracting for about 86,000 acre-feet per year to supplement its own substantial Brazos River water rights during dry times. The agency supplies raw and treated water to municipal users along and near the Gulf Coast south of Houston, and for industrial and agricultural irrigation use.

The GCWA recently submitted a grant application to the U.S. Bureau of Reclamation for a regional seawater desalination feasibility study to evaluate large-scale seawater desalination and associated regional opportunities for leveraging conjunctive use of existing water resources. The U.S. Bureau of Reclamation came back and said the application was anticipated to receive $365,500 in federal funding; however, GCWA had to demonstrate that the 50% non-federal cost share requirement for the grant would be available. Hence, the BRA Board's formal adoption.

The non-federal cost share is proposed to be equally divided among GCWA, BRA, and the Harris-Galveston Subsidence District, with each entity providing a minimum of $121,833. GCWA anticipates contracting with an engineering firm to conduct the roughly year-long study.

"Hopefully, with this feasibility study, maybe this will be the start of actually getting a project down there someday that will work and will help us free up some water upstream," Brunett said.

Drought and Water

Recent rains across the Brazos River Basin over recent weeks allowed the BRA's Board of Directors to make up to 41,913 acre-feet of Interruptible Water available to agriculture, cities and industry in need of water during calendar year 2024. 

Thanks to the rain, after more than 550 days, the totality of water supply throughout the Brazos River Basin finally increased enough to move the System of 11 reservoirs out of the Stage 1 Drought Watch status in February 2024. The designation had been in place since Aug. 17, 2022.

Due to the drought, the Board had previously voted not to make Interruptible Water available in 2023. But currently, 7 of the System's 11 reservoirs are full or nearly full. 

Unfortunately, the remaining 4 reservoirs located within the Little River subsystem have not fared as well. 

As part of the vote to make Interruptible Water available, the Board of Directors also voted to exclude the Little River reservoir subsystem (Lakes Proctor, Belton, Stillhouse Hollow, Georgetown, and Granger) from Interruptible Water availability for 2024.

Lakes Belton and the Lake Stillhouse Hollow – Lake Georgetown subsystem remain under a Stage 2 Drought Warning, requiring a 10% reduction in use. Lake Proctor remains under Stage 4 Pro-Rata Curtailment, which mandates a 30% reduction in use.

The BRA received about 93 requests for Interruptible Water this year, said Aaron Abel, BRA's water services manager. The BRA has two standing contracts: long-term water contracts and Interruptible Water contracts. The Interruptible Water contracts are sold on a year-to-year basis depending on water availability.

Morris Sheppard Dam Improvements

The Board approved an additional $300,000 for a contract with Gannett Fleming Inc. for continued work on the Concrete Assessment and Service Life Extension project. The BRA contracted with Gannett Fleming, Inc. to assess the concrete structure of the dam and provide a long-term repair program to extend the dam's service life. Through this contract, Gannett Fleming will assist the BRA's Reservoir System Maintenance Unit if the expertise is needed. 

Completed in 1941 with the aid of the Depression-era Works Progress Program, the Morris Sheppard Dam stretches 2,700 feet long and 190 feet high, or one-half mile long and 13 stories high. 

The BRA has a talented group of 19 employees who are part of the RSMU that are doing the concrete work, said Mike McClendon, BRA's Upper Basin regional manager. If they run across something they haven't seen or need to talk to an engineering expert, this contract will allow for that. The RSMU works solely to maintain the Morris Sheppard Dam at Possum Kingdom Lake. This crew and their commitment to excellence have streamlined maintenance and improved project efficiency while saving the BRA millions over the years.

"They do an incredible job and save the BRA a tremendous amount of money," McClendon said. 

More information

The recent Brown Bag on the Brazos virtual public meeting held April 4, 2024 discussed upcoming projects for the Central Brazos River Basin. To view the program, go here. In the meantime, for updates on BRA current projects, go here. For information on the current drought situation, see our drought update videos here.  

For a complete list of Board actions from the meeting, go here. Or watch the full board meeting here. Sign up to receive email Board meeting notices here.

Still have questions? Email information@brazos.org.