119 Recent Investigations of the Hydrogeology Edwards (Balcones Fault Zone) Aquifer, the Trinity (Hill Country) Aquifer, and Their Interactions, South-Central Texas

Recent research into the hydrogeological characteristics of the Edwards (Balcones Fault Zone) and/or Trinity (Hill Country) aquifers, south-central Texas, including their inter-aquifer connections, vulnerability, and prospects for long-term sustainability given changes in population, land use, and climate of the region.

Monday, 20 October 2025
1:30 PM - 5:30 PM
HBGCC, 209

Hydraulic Characterization of the Lower Trinity Hosston Aquifer in Central Texas Using Available Municipal Data, Well Hydraulics and Water Level Monitoring

Paper number: 119-9
Program: Technical Sessions
Time: 3:45 PM – 4:00 PM

Authors

Abstract

The Lower Trinity Hosston aquifer represents a critical groundwater resource in Central Texas, yet its hydraulic properties and connectivity remain poorly understood. This study characterizes hydraulic connections within the Hosston aquifer in McLennan County, using available monitoring and local well hydraulic data. An ongoing collaborative project between Baylor University and the Southern Trinity Groundwater Conservation District utilizes a monitor well where the depth to water is approximately 900 feet to assess water level responses to pumping from three nearby production wells. Pumping operations are driven by municipal water demand with no experimental control, requiring passive monitoring of variable pumping schedules through peak summer usage periods. At this depth, groundwater monitoring presents significant logistical and technical challenges compared to more shallow aquifer studies. Continuous water level data logging, provided by the Texas Water Development Board, captures detailed aquifer responses to pumping events. Manual depth-to-water measurements were compared with automated monitoring data from sonic and pressure transducer dataloggers. Preliminary analysis reveals measurable water level fluctuations in the monitor well corresponding to pumping activities, indicating hydraulic connectivity within the aquifer system. The magnitude and timing of responses provide insights into aquifer characteristics and connectivity. Despite limited access to production well data, the monitoring approach demonstrates the potential for characterizing aquifer properties using available datasets. Key objectives include: (1) determining hydraulic connections between wells through water level response analysis, (2) evaluating local groundwater level trends from the single monitor well, and (3) determining aquifer test parameters from existing well completion, pumping, and monitoring data. The research results contribute to improved understanding of Trinity aquifer hydrogeology and provide a framework for groundwater management in Central Texas. The integration of regulatory monitoring data with academic research demonstrates an effective approach for characterizing deep aquifer systems where traditional aquifer testing may be logistically challenging. Results can  inform regional groundwater models and support evidence-based water resource planning for the Southern Trinity Groundwater Conservation District.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-413676

© Copyright 2025 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.