Technical Reports Document Library

Note:  This report is included for its historical value ; results may have been superseded by more recent studies.

Ground water users in the San Antonio area have been concerned about possible encroachment of saline water into the fresh-water-bearing part of the Edwards and associated limestones as the head in the aquifer changes. As a result, the program to resample observation wells tapping the zone of transition between water of good quality and saline water in the Edwards and associated limestones was begun in 1959. Chemical analyses compiled through 1962 were published by the Edwards Underground Water District (Garza, 1962), and this report presents the chemical analyses compiled during 1963. The resampling program is part of a more extensive hydrologic investigation carried on by the U. S. Geological Survey in cooperation with the Edwards Underground Water District, the Texas Water Commission, and the city of San Antonio.

Chemical analyses of water from 100 wells are listed in this report. Most of the wells are sampled twice a year, but some of the wells are not in continuous use and it is not possible to sample them that frequently. About 80 wells are sampled twice a year; the remainder have been placed on standby to be resampled when the wells are in use.

The water samples are analyzed in the laboratory of the U.S. Geological Survey in Austin, Tex., for specific conductance , pH, chloride, sulfate, bicarbonate, and hardness . A more complete analysis has been made for one of the samples from each well, and these analyses are on file in the offices of the Geological Survey in Austin and San Antonio.  Locations of wells and other data pertaining to the resampling program may be found in tables in the report.