During the intense March 2015 flood event, contaminant elements were remobilized in the Andes Mountains and El Salado Alto Basin, and concentrations increased in the El Salado Bajo Basin predominantly due to the creation of a hydrologic connection between adjacent basins. Despite the presence of world-class porphyry CuMo and iron oxide copper-gold deposits in the region, some of which have been mined since the end of the 19th century, concentrations of dissolved Cu are lower than previously reported. This is likely related to circumneutral pH and the complexation of Cu as a cation in contrast to As and Mo which might be stable as HAsO42- and MoO42-, respectively, in solution over long distances.