Skip Links

USGS - science for a changing world

Fact Sheet 2006–3145

Geohydrologic Framework of the Edwards and Trinity Aquifers, South-Central Texas

Thumbnail of and link to PDF (27 MB)Download Publication
Fact Sheet
PDF (2.7 MB)
Right-Click to 'Download' or 'Save As'

This five-year USGS project, funded by the National Cooperative Geologic Mapping Program, is using multidisciplinary approaches to reveal the surface and subsurface geologic architecture of two important Texas aquifers: (1) the Edwards aquifer that extends from south of Austin to west of San Antonio and (2) the southern part of the Trinity aquifer in the Texas Hill Country west and south of Austin. The project’s principal areas of research include: Geologic Mapping, Geophysical Surveys, Geochronology, Three-dimensional Modeling, and Noble Gas Geochemistry.

The Edwards aquifer is one of the most productive carbonate aquifers in the United States. It also has been designated a sole source aquifer by the U.S. Environmental Protection Agency and is the primary source of water for San Antonio, America’s eighth largest city. The Trinity aquifer forms the catchment area for the Edwards aquifer and it intercepts some surface flow above the Edwards recharge zone. The Trinity may also contribute to the Edwards’ water budget by subsurface flow across formation boundaries at considerable depths. Dissolution, karst development, and faulting and fracturing in both aquifers directly control aquifer geometry by compartmentalizing the aquifer and creating unique ground-water flow paths.

Version 1.1

Posted August 2007


Suggested citation:

Blome, C.D., Faith, J.R., and Ozuna, G.B., 2007, Geohydrologic Framework of the Edwards and Trinity aquifers, south-central Texas: U.S. Geological Survey Fact Sheet 2006-3145, 6 p.



Part or all of this report is presented in Portable Document Format (PDF); the latest version of Adobe Acrobat Reader or similar software is required to view it. Download the latest version of Acrobat Reader, free of charge or go to access.adobe.com for free tools that allow visually impaired users to read PDF files.

Accessibility FOIA Privacy Policies and Notices

Take Pride in America logo USA.gov logo U.S. Department of the Interior | U.S. Geological Survey
URL: https://pubs.usgs.gov/fs/2006/3145/index.html
Page Contact Information: Contact USGS
Page Last Modified: Tuesday, November 29 2016, 05:24:56 PM