Wilcox, Carrizo, Queen City, Sparta, and Yegua Aquifers, Central Texas: Structure and Brackish Groundwater

Study Summary:

The goals of the study are to (1) map and characterize the brackish parts of the major and minor aquifers of the study area in greater detail using existing water well reports, geophysical well logs, and available aquifer data and (2) build datasets that can be used for groundwater exploration and replicable numerical groundwater flow models to estimate aquifer productivity. The study area includes all or most of Bastrop, Bexar, Caldwell, Gonzales, Guadalupe, and Wilson counties and adjacent parts of the following counties: Atascosa, Fayette, Karnes, Lee, and Williamson. This study area was selected because seven water user groups recommended Carrizo-Wilcox Aquifer brackish groundwater desalination as a water management strategy in the 2012 State Water Plan.

The objectives of the study are to:

  • collect, analyze, and interpret thousands of water well and geophysical well logs;
  • map the geological boundaries of the Wilcox, Carrizo, Queen City, Sparta, and Yegua aquifers and the bounding aquitards: Midway, Reklaw, Weches, and Cook Mountain;
  • map the distribution of total dissolved solids in the aquifers;
  • map the distribution of key chemical parameters of interest to desalination;
  • map the net sand distribution in the aquifers;
  • estimate the volume of fresh and brackish water in the aquifers;
  • incorporate newly created information into the publicly available BRACS Database and study GIS datasets;
  • prepare and publish study findings in a peer-reviewed TWDB report.
Study Team Members:
John Meyer, Andrea Croskrey, Alysa Suydam, and Nathaniel van Oort
Study Start Date:
Spring 2013
Study Completion Date:
Summer 2019
The study will develop data and a report that will be available to researchers and decision-makers to assist in the site selection of future groundwater desalination and aquifer storage and recovery projects.

Study Details


Study Investigators:

Texas Water Development Board
1700 N. Congress Avenue
Austin, TX 78711

John Meyer, P.G.

Andrea Croskrey, P.G.

Alysa Suydam, P.G.

Nathaniel van Oort

Engaged Stakeholders:

Fayette County Groundwater Conservation District
255 Svoboda Lane, Rm 115
La Grange, TX 78945

Gonzales County Underground Water Conservation District
P.O. Box 1919
Gonzales, TX 78629

San Antonio Water System
2800 U.S. Hwy 281 North
San Antonio, Texas 78212

Stakeholder Meetings

Event Date
Stakeholder Meeting, Texas Water Development Board, Austin, Texas May 6, 2013
Stakeholder Meeting, Evergreen Underground Water Conservation District, Pleasanton, Texas November 19, 2015
Stakeholder Meeting, Evergreen Underground Water Conservation District, Pleasanton, Texas April 15, 2016
Stakeholder Meeting, Evergreen Underground Water Conservation District, Pleasanton, Texas June 06, 2017
Presentation at the 2019 Geological Society Association South-Central/North Central/ Rocky Mountain Section Meeting in Manhattan, Kansas March 25, 2019
Presentation at the Austin Geological Society meeting in Austin, Texas November 4, 2019


Final Report