The Prairie du Chien-Jordan aquifer is part of a sequence of sedimentary bedrock units in southeast Minnesota. The Jordan Sandstone is a white to yellow, fine- to coarse-grained sandstone. The Prairie du Chien Group comprises two dolomitic formations, which are vuggy and fractured and interbedded with thin layers of shale. The aquifer was deposited from Paleozoic seas that occupied the Hollandale embayment. The surface of the aquifer dips toward the interior of the embayment where it is as deep as 750 feet below land surface and as thick as 500 feet. Permeability is secondary in the Prairie du Chien Group because of solution cavities and fractures and is intergranular in the Jordan Sandstone. Water in the aquifer is confined and generally flows to the north and east into the Minnesota and Mississippi Rivers. A ground-water divide separates part of the flow southward into Iowa. This aquifer supplies more water than any other in the State. Quality of water is generally good throughout the aquifer. Calcium magnesium bicarbonate type water is most common. The potential for contamination from surface sources is low except near the Mississippi River valley, where the overlying drift is thin. The most serious water-quality problem is contamination by chemical wastes in St. Louis Park. (USGS)
Additional publication details
USGS Numbered Series
Hydrogeologic and water-quality characteristics of the Prairie du Chien-Jordan aquifer, Southeast Minnesota
Water-Resources Investigations Report
13 maps on 2 sheets ; 27 x 26 cm., sheets 88 x 101 cm., folded in envelope 30 x 24 cm.