Calcium, magnesium, and sodium significantly influenced the adsorptive capacity of activated carbon for fulvic acids from three sources, including a natural groundwater supply. The experimental procedures used were batch equilibrium experiments and column studies. After demonstration of equilibrium conditions, effects of the salts on various fulvic acids, the Freundlich isotherm, and column operation were examined. Combined effects of salt and pH and effects on other organic anions, such as DHBA, EDTA, citric acid, and aspartic acid, are described. Includes 55 references, tables, figures.