Arkansas water regulations require metering on ground-water withdrawals for all sustaining aquifers named by the Arkansas Natural Resources Commission. Repercussions of these regulations have resulted in ground-water users contesting the aquifer in which their wells are screened. As a result, the agency responsible for enforcing the regulations requires a quick, reliable method to determine the primary aquifer of a well given the location and depth.  As part of the Mississippi Embayment Regional Aquifer Study, readily available geophysical logs were compiled in digital form. Depths to the top of aquifers and confining units were interpreted from the geophysical information and used to create three-dimensional (3D) surfaces of the top of each formation. To allow dynamic access to the unit information, a web site that incorporates interactive map capability was designed. The user selects the well location on the map and enters information such as well depth or screened interval. Next, the 3D surfaces are queried and a virtual well and stratigraphic column for that location is created. Furthermore, to assess the confidence in the web-based stratigraphic database and 3D surfaces, the locations and images of nearby geophysical logs are also available from the web site. In addition, previous map publications of formation tops have been scanned and georeferenced. Each map may be activated to compare previous interpretations of the formation tops to the current surfaces. In conclusion, the location and depth to the top of aquifers and confining units as well as their respective thicknesses allow State agencies as well as the general public to gain insight for the management of ground-water resources. Accordingly, as part of the U.S. Geological Survey Ground-Water Resources Program’s effort to determine ground-water availability, the surfaces developed in this study are being used to create the framework for a ground-water flow model of the Missisippi Embayment.