The Edwards aquifer in the San Antonio region has two distinct zones of different salinity. The down- dip limit of freshwater, locally known as the 'bad- water' line, separates saline water of 1,000 milli- grams per liter or greater from freshwater to the north and west. The saline-water zone is less transmissive and contains more dolomite and other soluble minerals than the freshwater zone. Dedolomitization has been proposed as the primary processes affecting the development of the large secondary porosity responsible for the large transmissivity of the freshwater zone. The data collected from a test-drilling and monitoring study, located in a transect across the interface in San Antonio, indicated that this conceptual model of dedolomitization and the resultant secondary porosity in the freshwater zone is appropriate, at least near the interface. One monitor well, located in the transition zone near a freshwater well field, might be sensitive to future water-level and water- quality changes that could occur in the Edwards aquifer.
Additional Publication Details
USGS Numbered Series
Analysis of data from test-well sites along the downdip limit of freshwater in the Edwards Aquifer, San Antonio, Texas, 1985-87
Water-Resources Investigations Report
U.S. Geological Survey ;
USGS Earth Science Information Center, Open-File Reports Section [distributor],