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TWDB Releases Report 383: Brackish Groundwater in the Gulf Coast Aquifer, Lower Rio Grande Valley, Texas

For immediate release. Contact: Media Relations at 512-463-5129

AUSTIN  (October 17, 2014)  Within the next 50 years, the population and municipal demand for water in the Lower Rio Grande Valley are expected to double and the production of desalinated brackish groundwater quadruple.

The Texas Water Development Board (TWDB) conducted a study of the Lower Rio Grande Valley as part of its Brackish Resources Aquifer Characterization System (BRACS) program. BRACS was established in 2009 to map and characterize the state's brackish groundwater and facilitate planning of desalination projects.

Presently, the study area has seven desalination plants that have a collective capacity to produce about 20 million gallons per day of treated water. An additional 23 desalination projects in the area have been recommended in the 2012 State Water Plan.

Much of the groundwater in the Gulf Coast Aquifer in the study area has total dissolved solids concentration in excess of 1,000 milligrams per liter and does not meet drinking water quality standards. Using existing groundwater quality data and geophysical well logs, we mapped 21 areas of unique salinity profiles consisting of stacked salinity zones (ranging from fresh water [less than 1,000 milligrams per liter of total dissolved solids] to brine [more than 35,000 milligrams per liter of total dissolved solids) that extend from ground surface to the base of the aquifer. The Gulf Coast Aquifer in the study area contains more than 40 million acre-feet of slightly saline groundwater, 112 million acre-feet of moderately saline groundwater, and 123 million acre-feet of very saline groundwater in the study area.

A published report, GIS data sets, the BRACS Database, and a database dictionary are available on the TWDB website.

Access to all of the geophysical well logs and water well reports used in the study are available upon request.

The TWDB is the state agency charged with collecting and disseminating water-related data, assisting with regional planning, and preparing the state water plan for the development of the state's water resources. The TWDB administers cost-effective financial assistance programs for the construction of water supply, wastewater treatment, flood control, and agricultural water conservation projects.