Abstract: Dissolved constituents in seepage from fly-ash settling ponds bordering part of the Indiana Dunes National Lakeshore (the Lakeshore) have increased trace elements, and gross alpha and gross beta radioactivity in the ground water and surface water downgradient from the settling ponds. Data suggest that concentrations of some dissolved trace elements may be greater beneath interdunal pond 2 than in the pond. The soil system downgradient from the settling ponds seems to have affected the concentrations of dissolved ions in the settling-ponds than in the ponds. Where organic material was present downgradient from the settling ponds, concentrations of arsenic, fluoride, molybdenum, potassium, sulfate, and strontium were greater in the ground water than in the ponds. In contrast, the concentrations of cadmium, copper, nickel, aluminum, cobalt, lead, and zinc were less.

From abstract: Sedimentary rocks of Cambrian and Ordovician age form a major aquifer system in most of Wisconsin and Iowa, northern Illinois, northwestern Indiana, southeastern Minnesota, and northern Missouri. Many metropolitan areas depend on the aquifer for all or part of their water supplies. Declines in potentiometric head have been large in the most heavily pumped areas, most notably Chicago, Milwaukee-Waukesha, Minneapolis-St. Paul, and Des Moines.