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

摘要

The U.S. Geological Survey (USGS), in cooperation with the San Antonio Water System (SAWS), collected data during 200411 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periods, the water-level altitude in the monitoring well generally increased as the total volume of water being withdrawn from all wells at the ASR site decreased and generally decreased as the total volume of water being withdrawn from all wells increased.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.