BRACKISH RESOURCES AQUIFER CHARACTERIZATION SYSTEM (BRACS) FOR TEXAS GROUNDWATER

Brackish groundwater is being pursued in Texas to bolster the state water supply. A statewide understanding of the location, depth, and quality of brackish groundwater is being improved to a regional scale, with publicly available data, to further the science and aid responsible development. Since 2009, the Texas Water Development Board’s Brackish Resources Aquifer Characterization System (TWDB BRACS) has developed methodologies, tools, databases, geographic information systems (GIS) data, and reports for five Texas aquifers. Seven additional projects were contracted to meet the 84^th Texas Legislature’s House Bill 30 requirement to map the brackish extent of the major and minor aquifers by 2022. The methodology so far uses geophysical well logs to map the extent and lithology of the aquifer, water quality measurements supplemented with water salinity calculated from resistivity log interpretations to interpolate the extent of salinity classes, and GIS to estimate volumes. Additionally, a customized Access database manages thousands of publicly available well logs, stratigraphic picks, lithologic picks, water quality measurements, and water quality calculations. Statewide, groundwater with 1,000 to 10,000 mg/L total dissolved solids was estimated to be 2.7 billion acre‐feet in 2003. Completed BRACS program studies estimated 85 million acre-feet of brackish groundwater in the Pecos Valley Aquifer, 152 million acre-feet in the Lower Rio Grande Valley of the Gulf Coast Aquifer, and 58 million acre-feet in the combined Queen City and Sparta aquifers in Atascosa and McMullen counties. Current BRACS studies include the central region of the Upper Coastal Plains aquifers and the Lipan Aquifer. The program has contracted projects for all or parts of the Blaine, Blossom, Carrizo-Wilcox, Gulf Coast, Nacatoch, Trinity, and Rustler aquifers. Not all of the estimated brackish groundwater can be economically produced, but the estimates provide an indication of the potential of this important resource. Study reports and data are available on the TWDB website http://www.twdb.texas.gov/innovativewater/bracs/studies.asp. These regionally studies provide a geologic framework of compiled data and interpretations for the next generation of investigations into brackish groundwater in Texas.