Geology and water-supply potential of the Anoka Sand Plain aquifer, Minnesota

Intensified land development on the Anoka sand plain necessitates a better understanding of the hydrogeology of the surficial outwash deposits of the area. The Anoka sand-plain aquifer consists of outwash attributable to two different ice lobes. Predominant grain size of the upper outwash decreases and sorting coefficient increases from west to east. Till or lake deposits underlie most of the surficial outwash. In some areas, these deposits are absent and the aquifer is directly underlain by bedrock, mainly sandstone. Preliminary study indicates that parts of the aquifer may yield several hundred to more than 1,000 gallons of water per minute to properly developed large-diameter wells. Storage in the aquifer is estimated to be 2,000 billion gallons and annual withdrawals approaching 250 billion gallons may be sustained. More detailed analysis is essential for proper management and optimum use of the resource.