Cl/Na molar ratios versus Cl- and Na+ concentrations (mg/L) in drinking waters wells of Allegan County Michigan (data from Michigan Department of Environmental Quality).
A. Cl- with Cl/Na ratios < 15, B. Na+ with Cl/Na ratios < 15, Cl- with Cl/Na ratios <5, and D. Na+ with Cl/Na ratios <5.