Tom Green County is situated within the discharge zone of the Permian Basin regional flow system in West Texas. Analysis of hydrochemical facies and ionic ratios of major chemical constituents suggests that a significant portion of the saline groundwater in the area is a combination of subsurface brine flowing eastward from the Permian Basin and locally recharged, shallowly circulating meteoric water. Aquifers that typically contain relatively fresh water in outcropping Paleozoic rocks exhibit the presence of brine and hydrocarbons at shallow depths ranging from 200 to 900 feet (60 to 270 meters) just a few tens of miles to the west. The chemical composition of groundwater is closely linked to the outcrop of Paleozoic formations from which brine is discharged.Bureau of Economic Geolog
