Hill Country portion of the Trinity Aquifer Groundwater Availability Model (GAM)

This map shows the extent and location of the Hill Country portion of the Trinity Aquifer Groundwater Availability Model.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.

Conceptual model update for the Hill Country Trinity Aquifer GAM

Conceptual Model Report

Conceptual Model Report for the Hill Country Trinity Aquifer Groundwater Availability Model


Stakeholder Advisory Forums (SAF)

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

ID Date Location
SAF 1 6/5/2017 San Antonio, Texas - Southwest Research Institute
SAF 2 7/13/2018 San Antonio, Texas - Southwest Research Institute
Current GAM: Hill Country Trinity Aquifer

Model Report

"Groundwater Availability of the Trinity Aquifer, Hill Country Area, Texas: Numerical Simulations through 2050." - Original model

"Groundwater Availability Model for the Hill Country Portion of the Trinity Aquifer System, Texas." - Updated model

"A Comparison of the Old and New Groundwater Availability Models for the Hill Country Portion of the Edwards and Trinity Aquifers."


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.


Stakeholder Advisory Forums (SAF)

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

ID Date Location
SAF 3 8/17/2009 Kerrville, Texas - Upper Guadalupe River Authority Auditorium (125 Lehmann Dr)
SAF 2 12/12/2006 Johnson City, Texas - Blanco-Pedernales Groundwater Conservation District (601 West Main)
SAF 1 6/7/2005 Boerne, Texas - Kendall County Historic Courthouse

Other Resources

Please see the Trinity Aquifer page for other reports and publications.

For model runs see the GMA 9 page.

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