DETERMINATION OF HYDROCHEMICAL FACIES IN PRESIDIO COUNTY USING HISTORICAL GROUNDWATER CHEMISTRY DATA

Geochemical data archived in the Texas Water Development Board Water Well Database were obtained and used to delineate hydrochemical facies in Presidio County, Texas. Chemistry data taken from well samples includes basic field parameters (pH, specific conductance) and major cation and anion concentrations. These data were entered into an ArcView GIS database and used to develop maps showing stiff diagrams, total dissolved solids distributions, and chloride concentrations. Piper diagrams were used to determine hydrochemical facies distributions throughout the county. The chemistry data and local geology maps were used to infer groundwater flow paths and geochemical reactions which could be controlling groundwater chemistry.