Relationships Between Ground‐Water Silica, Total Dissolved Solids, and Specific Electrical Conductivity

Specific electrical conductivity (SEC), total dissolved solids (TDS), and silica (SiO 2 ) are ground‐water quality parameters routinely measured in a laboratory. Electrical conductivity measurements are made quickly and are less costly than TDS measurements. Once the relationship between the parameters is determined by regression analysis, TDS can be estimated quickly from the SEC and SiO 2 measurements. Water quality data from 25 city wells in Fresno, California, and historical ground‐water quality data from the adjacent San Joaquin River/Kings River alluvial interfan (central San Joaquin Valley, California), the Kaweah River alluvial fan, and the Kern River alluvial fan (southern San Joaquin Valley) were used in this investigation. For the specific hydrologic areas studied, the model's TDS predictive ability is improved when SiO 2 is included with SEC as the independent variables.