Central portion of the Carrizo-Wilcox Aquifer Groundwater Availability Model (GAM)

Model users might find the information presented in the previous GAM, Carrizo-Wilcox, Queen City, Sparta Aquifers Groundwater Availability Model, useful.

This map shows the extent and location of the central portion of the Carrizo-Wilcox Aquifer GAM.In 2015 the Texas Water Development Board (TWDB) contracted with INTERA Inc. (teamed with RW Harden and Associates, GSI Environmental Inc., Alan Dutton, Tom Ewing, and John Doherty) to evaluate faults in the central portion of the Carrizo-Wilcox Aquifer and improve their representation in an updated groundwater availability model for the central portion of the Carrizo Wilcox, Queen City, and Sparta Aquifers. The project was completed at the end of 2018.

Current GAM

In a meeting on July 24, 2020, Groundwater Management Area 12 members voted to have their consultants modify the Groundwater Availability Model for the central portion of the Carrizo-Wilcox, Queen City and Sparta aquifers. The modification updated the transmissivity properties of the Simsboro Aquifer in the vicinity of the Vista Ridge well field using newly obtained aquifer pumping test data. The modification resulted in relatively minor changes to the statistics of the model calibration from 1930 to 2020. This modified model (v.3.02, 2020) was reviewed and approved by TWDB staff and replaces the version 3.01 (2018) groundwater availability model for the central portion of Carrizo-Wilcox, Queen City and Sparta aquifers.


Model Reports

The Final Numerical Model Report v.3.01 (2018) was not replaced but is supplemented by the GMA 12 Update to The Groundwater Availability Model for the Central Portion of the Sparta, Queen City, and Carrizo-Wilcox Aquifers report.

All reports can be found below:

Final Numerical Model Report v.3.01 (2018)

GMA 12 Updateds to the Final Numerical Model Report v.3.02 (2020)

GMA 12 Update to The Groundwater Availability Model for the Central Portion of the Sparta, Queen City, and Carrizo-Wilcox Aquifers


Model Files and Associated Data

Please see the GAM files download page for a copy of the model files for the Groundwater Availability Model for the Central Portion of the Sparta, Queen City, and Carrizo-Wilcox Aquifers v.3.02 (2020).

Aquifer data is only available as a package for the entire model area and requires GIS software for processing. Please see the GAM files download page for aquifer data.


Stakeholder Advisory Forums (SAF)

Send us an email if you would like to receive SAF notifications.

ID Date Location
SAF 2 04/27/2017 Milano, Texas
SAF 1 11/20/2015 Milano, Texas

Other Resources

Please see the Carrizo-Wilcox, Sparta, and Queen City aquifer pages for other reports and publications.

For model runs see the GMA 12 page.

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