Brackish Groundwater Issues in Texas
By Ric Jensen
Much of Texas’ groundwater is adversely affected by varying levels of salinity, which is measured by the concentrations of salts or total dissolved solids (TDS). Although TDS can be influenced by substances not related to salinity, it is typically used to determine salinity levels for most purposes.
Varying levels of salinity are defined as “brackish” water, having a TDS measurement of 1,000 to 10,000 parts per million (ppm) and “brine” with concentrations of greater than 10,000 ppm.
Although slightly saline groundwater (1,000 to 3,000 ppm TDS) can be used for crop irrigation and livestock watering, the drinking water standard for TDS, set by the Texas Commission on Environmental Quality, is 1,000 ppm.
According to the Texas Water Development Board (TWDB), brackish groundwater is present in most of Texas’ minor and major aquifers, resulting in a total volume of brackish groundwater of more than 2.5 billion acre-feet. An acre-foot is the volume of water needed to cover an acre of land at a depth of one foot (gallon).
In general, areas containing significant brackish groundwater resources can be found in West Texas, North Central Texas, Central Texas, and the Southern Gulf Coast. Major aquifers that contain brackish groundwater include the Ogallala, Trinity, Carrizo-Wilcox, Edwards, Edwards-Trinity, Gulf Coast, Seymour, Hueco and Mesilla Bolsons.
Efforts to capture, treat and reuse brackish groundwater are already underway in Texas. El Paso, for example, is now developing a desalination plant to treat brackish groundwater from the Hueco Bolson aquifer. Additionally, Brownsville has successfully developed a water supply source from brackish groundwater of the Gulf Coast Aquifer.
Several experts suggest it may now be economically feasible to recover, treat and reuse brackish and saline groundwater because advances in technology are making this process more efficient and less costly.
