Technical Reports Document Library

This report is included for its historical value; results may have been superseded by more recent studies.

A program to resample observation wells tapping a zone of transition between water of good quality and saline water in the Edwards and associated limestones was begun in 1959. The chemical analyses of the resampling program are being used to detect possible encroachment of saline water into the freshwater areas as the head in the aquifer changes. Those analyses compiled through 1964 were published by the Edwards Underground Water District (Garza, 1962b, 1964, 1965), and this report presents the chemical analyses compiled during 1965. This 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.

Listed in this report are chemical analyses from 72 wells most of which are sampled twice a year, put some are sampled only once a year because they are little used. The water samples are analyzed in the laboratory of the U.S. Geological Survey in Austin, Texas, for specific conductance, pH, chloride, sulfate, bicarbonate, and hardness. A more complete analysis has been made for one sample from each well, and these analyses are on file in the offices of the Geological Survey in Austin and San Antionio. Locations of wells and other data pertaining to the resampling program may be found in tables in the report.