Groundwater resources associated with sediments filling the Marion and Mahomet Valley Sections of the Lafayette Bedrock Valley System vary from miniscule to substantial, reflecting the wide range of glacigenic aquifer facies contained in the fill. These aquifer facies include braid-stream deposits that range from thin units within till sequences to immense, valley-filling masses. Also included is a variety of proximal to distal, subaerial to subaqueous, fan and fan-delta deposits; these range from thick masses of ice-proximal, cobbly rubble interspersed with thin diamicts and clays, to thin, discontinuous lentils of sand confined within lacustrine clays. Valley-fill aquifers are confined by capping till units, except where exhumed at the crossings of the Maumee-Wabash Trough (modern Wabash River Valley). A variety of aquifers typically are available within the valley-capping sediments; for this reason, much of the deep valley-fill has not been extensively explored or developed. Some valley-fill aquifers are so thin and/or deeply buried that their exploitation is unlikely, but others are so thick and areally extensive that exploitation easily can support sustainable yields of tens of millions of gallons per day.