3-D Models of High Concentrations of As and Mn in Glacial Aquifer Groundwater Geology Plays a Key Role in Glacial Aquifer System Groundwater Quality Machine-learning models predict where concentrations of these drinking-water contaminants likely to be high Learn More Release Date: April 27, 2021 New 3-dimensional models predict where high concentrations of arsenic and manganese are likely to occur in the glacial aquifer system, reports a new study from the U.S. Geological Survey National Water Quality Program. The glacial aquifer system, which underlies parts of 25 states across the northern U.S., supplies groundwater for about 30 million people. Predictions of the occurrence of high concentrations of arsenic and manganese in the glacial aquifer system are based in part on new models of oxidation-reduction conditions, which are related to the amount of dissolved oxygen in the water, and pH.