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Scientific Investigations Report 2012–5260

Prepared in cooperation with the San Antonio Water System

Water-Level Altitudes and Continuous and Discrete Groundwater Quality at and near an Aquifer Storage and Recovery Site, Bexar, Atascosa, and Wilson Counties, Texas, June 2004–September 2011

By Cassi L. Crow

 

Thumbnail of and link to report PDF (1.94 MB)Abstract

The U.S. Geological Survey (USGS), in cooperation with the San Antonio Water System (SAWS), collected data during 2004–11 to characterize the quality of native groundwater from the San Antonio segment of the Edwards aquifer (hereinafter, Edwards aquifer) and preinjection and postinjection water from the Carrizo aquifer (informal name commonly applied to the upper part of the Carrizo-Wilcox aquifer in the area) at and near an aquifer storage and recovery (ASR) site in Bexar, Atascosa, and Wilson Counties, Texas. Daily mean water-level altitude, water temperature, and specific conductance were measured continuously in a monitoring well on the ASR site to determine how injection and withdrawal at the ASR site might affect local groundwater. Groundwater samples were collected and analyzed for selected physical properties and constituents to characterize the quality of native groundwater from the Edwards aquifer and preinjection and postinjection water from the Carrizo aquifer near the ASR site to provide a better understanding of possible changes in the quality of groundwater near an active ASR site that might result from the mixing of water from different aquifers. During injection periods, the water-level altitude in the monitoring well generally increased as the amount of water being injected into all wells at the ASR site increased and decreased as the amount of water being injected into all wells at the ASR site decreased. During withdrawal periods, the water-level altitude in the monitoring well generally increased as the total volume of water being withdrawn from all wells at the ASR site decreased and generally decreased as the total volume of water being withdrawn from all wells increased. Daily mean water temperature fluctuated by less than 1 degree Celsius and was determined to be independent of injection or withdrawal conditions at the ASR site. Changes in daily mean specific-conductance values measured at four depths in the monitoring well at the ASR site occurred without regard to total ASR site injection or withdrawal volumes. No substantial differences were measured over time in major-ion, trace-element, or isotope chemistry of water samples collected from the wells that supplied water from the Edwards aquifer. Little variation in water chemistry was detected in the samples collected from four wells designed to inject and withdraw water at the ASR site, regardless of whether the ASR site was injecting or withdrawing water. The similarity of major-ion and isotope chemistry between the Edwards aquifer source wells and the four ASR wells indicates that little, if any, migration of injected water away from the ASR wells has occurred. In a well located closest to the ASR site in the direction of regional flow for the Carrizo aquifer, a greater alkalinity value and a smaller concentration of chloride were measured in the most recent sample than in all other samples collected at this well. Substantial increases in dissolved iron and manganese concentrations also were observed in this well. The increased alkalinity value and dissolved iron and manganese concentrations and the decreased chloride concentration in the well could indicate that the injected water from the Edwards aquifer had begun to move into at least a part of the strata supplying these wells and might be causing iron and manganese mobilization in the Carrizo aquifer.

First posted Dec. 11, 2012

For additional information contact:
Director, Texas Water Science Center
U.S. Geological Survey
1505 Ferguson Lane
Austin, Texas 78754-4501
http://tx.usgs.gov/

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Suggested citation:

Crow, C.L., 2012, Water-level altitudes and continuous and discrete water quality at and near an aquifer storage and recovery site, Bexar, Atascosa, and Wilson Counties, Texas, June 2004–September 2011: U.S. Geological Survey Scientific Investigations Report 2012–5260, 85 p., 7 apps.


Contents

Abstract

Introduction

Methods of Investigation

Water-Level Altitudes and Continuous Groundwater Quality

Discrete Groundwater Quality

Summary

References

Appendix 1. Water-Quality and Isotope Data from Wells Sampled at and near an Aquifer Storage and Recovery Site, Bexar, Atascosa, and Wilson Counties, Texas, 2004–11

Appendix 2. Relative Percent Difference for Duplicate Water-Quality and Isotope Data from Wells Sampled at and near an Aquifer Storage and Recovery Site, Bexar, Atascosa, and Wilson Counties, Texas, 2004–11

Appendix 3. Daily Mean Water-Level Altitude at U.S. Geological Survey Station 290802098232901 AY–68–53–928 (C8), Bexar County, Texas, 2009–11

Appendix 4. Daily Total Volume of Water Injected at an Aquifer Storage and Recovery Site, Bexar County, Texas, 2004–11

Appendix 5. Daily Total Volume of Water Withdrawn at an Aquifer Storage and Recovery Site, Bexar County, Texas, 2004–11

Appendix 6. Daily Mean Water Temperature at U.S. Geological Survey Station 290802098232901 AY–68–53–928 (C8), Bexar County, Texas, 2009–11

Appendix 7. Daily Mean Specific Conductance at U.S. Geological Survey Station 290802098232901 AY–68–53–928 (C8), Bexar County, Texas, 2009–11

 

 


 


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