Frequently Asked Questions
- What is BRACS?
- What is brackish groundwater?
- How much brackish groundwater is present in Texas?
- What does a BRACS project consist of?
- How do I obtain BRACS project reports and data?
- How do I obtain digital geophysical well logs?
- How do you select which areas of Texas to study?
- What projects have you completed, and which projects are in progress?
- How can I get a copy of the BRACS Database?
- How can I get a copy of the 2003 brackish groundwater study?
- Have there been other brackish groundwater studies in Texas?
- What areas of the state are considering brackish groundwater desalination?
- How do you remove the salts from brackish groundwater?
- How do I get a copy of the BRACS contract reports and deliverables?
- How deep is the brackish groundwater?
- Where is the brackish groundwater in Texas?
- How does water become brackish?
- Whom can I contact at the TWDB for more information about BRACS?
Answers to Frequently Asked Questions
1. What is BRACS?
TWDB's Brackish Resources Aquifer Characterization System (BRACS) program maps and characterizes the brackish aquifers of Texas in greater detail than previous studies. The study deliveralbes include a report with companion geographic information system data files. Data is also entered into the BRACS Database.
2. What is brackish groundwater?
Brackish groundwater contains dissolved minerals in the range of 1,000 to 9,999 milligrams per liter (mg/L). Water is classified as fresh (0–999 mg/L), slightly saline (1,000–2,999 mg/L), moderately saline (3,000–9,999), and saline (greater than 10,000 mg/L). For comparison, seawater contains approximately 35,000 mg/L of total dissolved solids.
3. How much brackish groundwater is present in Texas?
Texas has an abundance of brackish groundwater, estimated at more than 2.7 billion acre-feet according to a 2003 study completed by LBG-Guyton and Associates. Brackish groundwater may be located in deeper and less productive portions of aquifers. In other aquifers, the brackish and fresh water comingle. In such instances, determining volumes is problematic.
4. What does a BRACS study consist of?
A typical study involves evaluating hundreds to thousands of existing water well records, petroleum well geophysical well logs, and geologic reports that have been prepared for the water–bearing formations in the region. A comparison of the geologic structure of water–bearing formations (top, bottom, and lateral extent) between existing datasets and well records is evaluated. If the existing structure is not accurate, new formation structure is compiled. The water–bearing portions of the aquifer (typically the sand layers) are mapped along with estimated salinity from water well records and assessment of geophysical well logs. This information is then used to prepare estimated volumes of brackish groundwater. All of this data are entered into the BRACS Database and geographic information system files prepared. The project is summarized in a written report.
5. How do I obtain BRACS study and project reports and data?
Each of the BRACS studies/projects consists of report, digital geographic information system (GIS) files, database tables, and digital geophysical well logs. The project reports and GIS files are available on TWDB's BRACS Documents webpage.
6. How do I obtain digital geophysical well logs?
Presently, the digital geophysical well logs are available only by request. You can download a copy of the database (see instructions below) or view the Water Data Interactive (WDI) map-based approach (select the Brackish Groundwater Database application) to determine available well control. The majority of the logs are in a TIFF (tagged image format) and file sizes are variable, depending on the quality of the digital image. The logs are filed with a state and county folder system. Generally, to save handling time, we provide the entire county folder of logs unless an individual requests a few specific logs. Learn more about requesting well logs at the BRACS Geophysical Well Logs web page.
Please contact John Meyer (512-463-8010) or Andrea Croskrey (512-463-2865) with your request. They can give you more details about the availability of logs and other related information.
7. How do you select which areas of Texas to study?
The Pecos Valley Aquifer in West Texas was selected as the pilot study because of the need for brackish groundwater in the region and the plentiful amount of water in this aquifer. At this time, selection of additional project areas are based on recommended desalination projects listed in the state water plan.
8. What studies have you completed, and which studies are in progress?
The four studies that we have completed are:
- Brackish Groundwater in the Gulf Coast Aquifer, Lower Rio Grande Valley, Texas, September, 2014.
- Queen City and Sparta Aquifers Atascosa and McMullen Counties, Texas: Structure and Brackish Groundwater, May 2014
- Geologic Characterization of and Data Collection in the Corpus Christi Aquifer Storage and Recovery Conservation District and Surrounding Counties, September, 2012
- Pecos Valley Aquifer project, June 2012
The study that we are currently working on are:
- Wilcox, Carrizo, Queen City, Sparta, and Yegua Aquifers, Central Texas: Structure and Brackish Groundwater
- Lipan Aquifer: Structure and Brackish Groundwater
9. How can I get a copy of the BRACS Database?
The BRACS Database in Microsoft® Access® 2007 format is available in a compressed file format (Winzip®) for download from the TWDB Website.
A companion report titled Brackish Resources Aquifer Characterization System Database Data Dictionary (Second Edition, TWDB Open-File Report 12-02, September 2014) describes the database design and the primary tables including field names, types, lookup table references, and field contents. Each of the five primary project related tables are also described.
10. How can I get a copy of the 2003 LBG-Guyton and Associates brackish groundwater study?
A PDF copy of the 2003 LBG-Guyton and Associates report (Brackish Groundwater Manual for Texas Regional Water Planning Groups) is available for download from the TWDB Website.
11. Have there been other brackish groundwater studies in Texas?
A Survey of the Subsurface Saline Water of Texas completed in 1972 as TWDB Report 157 is available in an eight volume compendium on the TWDB Website. Please scroll down the list for links to each of the seven volumes.
Another report, U.S. Geological Survey Water Supply Paper 1365, completed in 1965 by A.G. Winslow and L.R. Kister is available in PDF format on the U.S. Geological Survey Website.
Many of the hydrogeology reports completed by the state and the U.S. Geological Survey discuss brackish portions of the major and minor aquifers in the lower salinity ranges (for example, 1,000 to 3,000 milligrams per liter of total dissolved solids). These reports, often completed by county, groups of counties, or aquifer wide, are available on the TWDB Publications Website.
As part of the BRACS program, TWDB developed a bibliography of Texas geology. The database contains over 7,800 references from reports, books, journals, conference proceedings, scientific magazines, abstracts, theses, and dissertations. The bibliography includes topics on Texas geology, hydrogeology, geochemistry, geophysics, and other topics of interest to the BRACS program. The database is available on TWDB's Project Website as a Zipped MS Access® file.
12. What areas of the state are considering brackish groundwater desalination?
In the 2017 State Water Plan, eight regional water planning groups (regions E, F, H, J, L, M, N, and O) included groundwater desalination as a recommended water management strategy. In total, there are 78 recommended water management strategies that will help meet the water needs of a water user group. If these recommended strategies are implemented, groundwater desalination will produce about 111,000 acre-feet per year of additional water supply by decade 2070. This constitutes about 1.3 percent of all recommended water management strategies in the state water plan.
13. How do you remove the salts from brackish groundwater?
Reverse osmosis is the predominant desalination technology in Texas; 44 of 46 existing desalination facilities operating in the state use this technology.
14. How do I get a copy of the BRACS contract reports and deliverables?
All of the BRACS study reports with related geographic information system files and the BRACS contract reports and deliverables are available on TWDB's BRACS Documents.
15. How deep is the brackish groundwater?
It varies, from a few feet to thousands of feet deep. The depth depends on the aquifer and the geographic area of the state in which the aquifer is located. For lower salinity ranges (for example, 1,000 to 3,000 mg/L of total dissolved solids) of brackish groundwater, the TWDB's Groundwater Database can be used to provide an estimate. This database is available for download in Microsoft® Access® format.
Alternatively, well information can be reviewed in the Water Data Interactive (WDI) map-based Web browser. In the browser, select the Groundwater Database application.
For areas of the state without water quality data, geophysical well logs will need to be interpreted or direct measurements obtained from oil and gas operators.
16. Where is the brackish groundwater in Texas?
We have prepared several one-page maps showing the distribution of fresh and brackish water wells in Texas. These maps are available on TWDB's Desalination Maps Website.
Additionally, there are other brackish groundwater resources in geologic formations that are not designated as a major or minor aquifer. The lateral extent and potential volume of this resource are unknown.
17. How does water become brackish?
Some water is naturally brackish because groundwater dissolves minerals as it percolates through the aquifer. Some aquifers contain more evaporite minerals (salts deposited when seawater evaporated) than other aquifers, so the salinity of the groundwater is greater. In general, the longer the water is in contact with the aquifer minerals, the longer the groundwater has to dissolve some of those minerals.
Salinity can also be anthropogenic (man-made). Anthropogenic sources of salinity include water produced during oil and gas development, flow through improperly abandoned or deteriorated wells, agriculture chemicals, and recharge of higher salinity water from surface water bodies.
18. Whom can I contact at the Texas Water Development Board for more information about BRACS?
If you have any questions about the BRACS program, please contact John Meyer (512-463-8010) or Andrea Croskrey (512-463-2865).