Edwards Aquifer Hydrogeologic Report for 1994

Author Salthour SD, Waugh JR, O'Connor J and Bader RW
Year 1995
Description Annual report for 1994 on recharge, discharge, water levels and water quality in the Edwards Aquifer San Antonio Region
Report Number 95-07
Publisher Edwards Underground Water District
Location Edwards Aquifer - San Antonio Area
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The average estimated annual groundwater recharge to the Edwards aquifer in the San Antonio area from 1934 through 1994 was 676,600 acre-feet. Recharge in 1994 was 538,100 acre-feet, which was well below the regional average. The lowest annual recharge of 43,700 acre-feet occurred in 1956 and the highest annual recharge of 2,486,000 acre-feet occurred in 1992.

The estimated annual discharge from the Edwards aquifer through wells and springs in 1994 was 814,800 acre-feet, which was the 14th largest calculated annual discharge for the period of record (1934-1994). The lowest annual discharge through wells and springs for the same time period was 388,800 acre-feet which occurred in 1955.

Water level data for wells during 1994 reflected an above average volume of groundwater in storage in the Edwards aquifer during the year. In 1994, the District collected water quality samples from 55 wells, three springs, and seven streams and rivers. These samples were analyzed for 74 constituents and parameters which included common organic constituents, nutrients, dissolved organic carbon, metals and VOCs. Laboratory analyses indicated that samples from 18 wells contained detectable metal concentrations. These concentrations were well below the MCLs for those constituents. No detectable concentrations of pesticides were measured in the wells sampled in 1994. VOCs were detected in four wells at levels well below the limits set by current EPA drinking water standards.

Results of the District’s 1994 water quality monitoring program illustrate the continued excellent quality of water in the Edwards aquifer.