Frequency distribution of dissolved solids in ground water

The frequency distribution of dissolved‐solids content of ground waters in geologically and climatologically homogeneous terrane units commonly approximates a log‐normal distribution. A graphic logarithmic transformation is de‐scribed which permits rapid calculation of approximate values for the mean, standard deviation, and coefficient of variation. Statistical parameters calculated by this method show good agreement with known physical conditions in the terranes studied and are precise enough for use as a mea‐sure of variability of quality of ground waters for national planning purposes.