September 2023 Potentiometric Study of the Middle Trinity Aquifer, Central Texas

Topic: Sustainable Yield, Groundwater Modeling, and DFCs
Source: BSEACD
Format: Report
Year: 2024

The Middle Trinity Aquifer is a critical groundwater resource in Hays County, providing the sole source of drinking water to many residents living in the county. It is also the source of ecologically and culturally important artesian springs that provide baseflow to the Blanco River, which is the primary source of recharge to the Barton Springs segment of the Edwards Aquifer during times of severe drought. Synoptic water level studies provide valuable information on groundwater storage and flow dynamics within aquifers. Conducting multiple synoptic studies within a given aquifer at different times shows how groundwater levels and flow dynamics change over time, improving our understanding of how the aquifer responds to climatic stressors such as drought and anthropogenic stressors such as groundwater pumping. Synoptic potentiometric maps are also important datasets for calibration and validation of numerical groundwater models. Hunt et al., (2019) produced a potentiometric surface of the Middle Trinity from data collected in March 2018, a month which represented approximately “average” hydrologic conditions. In September 2023, staff from the BSEACD, cooperating with other staff from other groundwater conservation districts (GCDs),
land owners, and students from the University of Texas at Austin, conducted a synoptic water level study of the Middle Trinity Aquifer to assess aquifer conditions during a severe drought which was occurring at the time, and its still ongoing at the time of publication of this report. Data and preliminary analyses from the 2023 data collection efforts are provided in this report.