Southern portion of the Trinity Aquifer Groundwater Availability Model (GAM)
This model was previously referred to as the Hill Country portion of the Trinity Aquifer.
The Texas Water Development Board (TWDB) completed this model in 2000 in cooperation with the Trinity Aquifer Advisory Committee which includes members of local groundwater districts, river authorities, county governments, regional water planning groups, and concerned citizens.
In 2009, the TWDB completed an update to the model to include the Lower Trinity as a fourth model layer.
In 2017, the TWDB contracted with Southwest Research Institute to update the conceptual model for the Trinity Aquifer in the Hill Country region with the goal of incorporating the Trinity strata to the east into the Hill County Trinity GAM. The project is expected to be completed in 2019.
The report of the updated conceptual model for the Trinity Aquifer in the Hill Country region is available below.
Draft Model Report
Draft Model Report Appendices
Draft Model Files
Draft Model Supplemental Data (2.6 GB zipped)
Stakeholder Advisory Forums (SAF)
Send us an email if you would like to receive SAF notifications.
| ID | Date | Location | Slides | Video |
|---|---|---|---|---|
| SAF 1 | 07/13/2023 | Hybrid meeting, in-person at TWDB Office, 1700 N Congress Ave. Austin, Texas, online GoToMeeting | SAF 1 slides | Video recording |
| SAF 2 | 08/16/2024 | Online meeting Microsoft Teams | SAF 2 slides | Video recording |
| Technical Progress Meeting | 08/08/2025 | Online meeting Microsoft Teams | Technical Progress Meeting slides |
Model Files and Associated Data
Please see the GAM files download page for a copy of the model files.
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.
Other Resources
Please see the Trinity Aquifer page for other reports and publications.
For model runs see the GMA 9 page.