Water-quality indicators in the Prairie du Chien-Jordan Aquifer, southeastern Minnesota

The Prairie du Chien-Jordan aquifer, which consists of the dolomitic Prairie du Chien Group and the underlying Jordan Sandstone, extends over southeastern Minnesota (fig. 1). Water quality in the aquifer fluctuates areally and with depth throughout the aquifer. Differences in chemical constituent concentrations are a result of both natural hydrogeologic conditions and human activities.