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Fact Sheet 2013–3078

Prepared in cooperation with the San Antonio Water System

Borehole Geophysical, Fluid, and Hydraulic Properties Within and Near the Freshwater/Saline-Water Transition Zone, San Antonio Segment of the Edwards Aquifer, South-Central Texas, 2010–11

By Jonathan V. Thomas and Gregory P. Stanton

Thumbnail of and link to report PDF (2.07 MB)Introduction

The freshwater zone of the San Antonio segment of the Edwards aquifer is used by residents of San Antonio and numerous other rapidly growing communities in south-central Texas as their primary water supply source. This freshwater zone is bounded to the south and southeast by a saline-water zone with an intermediate zone transitioning from freshwater to saline water (transition zone). As demands on this water supply increase, there is concern that the transition zone could potentially move, resulting in more saline water in current freshwater supply wells. Since 1985, the U.S. Geological Survey, San Antonio Water System, and other Federal and State agencies have conducted studies to better understand the transition zone.

First posted September 30, 2013

For additional information contact:
Director, Texas Water Science Center
U.S. Geological Survey
1505 Ferguson Lane
Austin, Texas 78754

Part or all of this report is presented in Portable Document Format (PDF); the latest version of Adobe Reader or similar software is required to view it. Download the latest version of Adobe Reader, free of charge.

Suggested citation:

Thomas, J.V., and Stanton, G.P., 2013, Borehole geophysical, fluid, and hydraulic properties within and near the freshwater/saline-water transition zone, San Antonio segment of the Edwards aquifer, south-central Texas, 2010–11: U.S. Geological Survey Fact Sheet 2013–3078, 6 p.,



Hydrogeologic Setting

Description of Transects and Monitoring Wells

Borehole Geophysical, Fluid, and Hydraulic Properties

Hydraulics of Lateral Flow


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