The Mineral River—A Unique Tributary Chloride Load to Lake Superior

The Mineral River contributes a significant amount of chloride to Lake Superior, more than one-third of the total U. S. tributary input. This unique discharge is attributed largely to the mine dewatering process of the White Pine Copper Company. Chloride concentrations as high as 2,000 mg/L have been recorded at the mouth of the Mineral River. The impact of this discharge on Lake Superior is not known; however, it is postulated that increased chloride concentrations may enhance the introduction and adaptation of marine organisms into the Great Lakes.