The Paint Pots, a group of mineral springs in Kootenay National Park, British Columbia, produce acid water (pH = 2.5 to 3.5) with a high content of Fe, Zn, Mn, and Pb, derived from sulfide mineralization in the Cambrian rocks of the area. Oxidation of the Fe++ in the water and hydrolysis of the resulting Fe+++ produce a still lower pH in the water, a high redox potential, and a deposit of ferric (oxy) hydroxide. Less than half the available iron, approximately three-quarters of the manganese and zinc, and most of the lead are discharged into the Vermilion River. The strong dilution provided by the high flow rate of the Vermilion River prevents any serious pollution. A simple laboratory test shows that circulation of the acid spring water through crushed limestone will remove all the iron, introduce some oxygen, and reduce both the acidity and the redox potential to normal surface water values. Zinc, manganese, and lead are probably removed incompletely.