Groundwater Availability During Drought Conditions in the Edwards Aquifer, Hays and Travis Counties, Texas

B. B. Hunt and B. A. Smith
Barton Springs/Edwards Aquifer Conservation District, Austin, TX 

The Barton Springs segment of the Edwards Aquifer is an important water resource for municipal, industrial, domestic, recreational, and ecological needs. Recent studies have given us a better understanding of the amount of groundwater that will be available during a severe drought with increased demand.

This paper describes the methods used to characterize and quantify the impacts to water supply wells during drought-of-record conditions (e.g. 1950’s) and with increasing demand on groundwater. Potentiometric and saturated thickness maps of the aquifer representing drought conditions and computer-simulated drawdown from pumping were created. Well productivity (specific capacity) and construction data were compiled and evaluated with saturated thickness and potentiometric maps to estimate the number of wells that could be negatively impacted.

Results indicate that the southwestern, unconfined portion of the aquifer is the most susceptible to decreased saturated thickness under drought and is further reduced with increased pumping. Drought and pumping also decrease heads in the eastern confined portion of the aquifer. Up to 8% of water-supply wells in the District may have yield problems under drought alone. The combined effects of drought and pumping at an annualized rate of 10 cubic feet per second, currently permitted by the District, could result in negative impacts of up to 20% of the total water-supply wells in the District. These studies are a critical component of the management of the Edwards Aquifer and will be used to set sustainable yield policies for resource management by the District.

AAPG Search and Discovery Article #90032©2004 GCAGS 54th Annual Convention, San Antonio, Texas, October 10-12, 2004