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The average annual ground-water recharge to the Edwards aquifer in the San Antonio area, Texas, from 1934 through 1985 was 604,500 acre-feet. Recharge in 1985 was 1,003,300 acre-feet, which is the seventh highest estimated annual recharge since 1934. A maximum annual recharge of 1,711,200 acre-feet occurred in 1958, and a minimum annual recharge of 43,700 acre-feet occurred in 1956.

The calculated annual discharge by wells and springs in 1985 was 856,500 acre-feet. Annual discharge by wells and springs ranged from a maximum of 960,900 acre-feet in 1977 to a minimum of 388,800 acre-feet in 1955. In 1985, the annual discharge by wells was 522, 500 acre-feet. This is near the record high of 529,800 acre-feet in 1984.

Although water levels in many of the wells fluctuated near or above the midpoint between record high and low levels in 1985, the volume of ground water in storage in the aquifer was near average during most of the year. In 1985, substantial increases occurred during the fall and winter, and water levels then remained above average in most of the area.

Analyses of water samples from 94 wells and 3 springs in the Edwards aquifer show that the water quality in the freshwater zone is significantly better than the level established for public water systems. However, trace concentrations of organic compounds were detected in many of the analyses. Analyses of water samples collected from nine wells in Uvalde County showed concentrations of tetrachloroethylene in excess of 5 micrograms per liter. In 1985, samples were collected from wells along the “bad-water” line to detect changes in water quality as the potentiometric head in the Edwards aquifer changed.

Note: Large‐format versions of the plates for this report are available at:
https://www.edwardsaquifer.org/wp-content/uploads/2019/05/1987_Ozuna-etal_1985HydrologicData.pdf.