This data set represents the extent of the Pennsylvanian aquifers in the states of Pennsylavania, West Virginia, Ohio, Virginia, Kentucky, North Carolina, Tennessee, Alabama, Illinois, Indiana, and Michigan.

This data set represents the extent of the Southeastern Coastal Plain aquifer system in Kentucky, Tennessee, Mississippi, Alabama, Georgia, and South Carolina.

This data set represents the extent of the Piedmont and Blue Ridge crystalline-rock aquifers in the states of Alabama, Delaware, District of Columbia, Georgia, Maryland, New Jersey, New York, North Carolina, Pennsylvania, South Carolina, Tennessee, Virginia, West Virginia.

This geodatabase includes spatial datasets that represent the Mississippian aquifer in the States of Alabama, Illinois, Indiana, Iowa, Kentucky, Maryland, Missouri, Ohio, Pennsylvania, Tennessee, Virginia and West Virginia. The aquifer is divided into three subareas, based on the data availability. In subarea 1 (SA1), which is the aquifer extent in Iowa, data exist of the aquifer top altitude and aquifer thickness. In subarea 2 (SA2), which is the aquifer extent in Missouri, data exist of the aquifer top and bottom aquifer surface altitudes. In subarea 3 (SA3), which is the aquifer area of the remaining States, no altitude or thickness data exist. Included in this geodatabase are: (1) a feature dataset "ds40MSSPPI_altitude_and_thickness_contours that includes aquifer altitude and thickness contours used to generate the surface rasters for SA1 and SA2, (2) a feature dataset "ds40MSSPPI_extents" that includes a polygon dataset that represents the subarea extents, a polygon dataset that represents the combined overall aquifer extent, and a polygon dataset of the Ft. Dodge Fault and Manson Anomaly, (3) raster datasets that represent the altitude of the top and the bottom of the aquifer in SA1 and SA2, and (4) georeferenced images of the figures that were digitized to create the aquifer top- and bottom-altitude contours or aquifer thickness contours for SA1 and SA2. The images and digitized contours are supplied for reference. The extent of the Mississippian aquifer for all subareas was produced from the digital version of the HA-730 Mississippian aquifer extent, (USGS HA-730). For the two Subareas with vertical-surface information, SA1 and SA2, data were retrieved from the sources as described below. 1. The aquifer-altitude contours for the top and the aquifer-thickness contours for the top-to-bottom thickness of SA1 were received in digital format from the Iowa Geologic Survey. The URL for the top was ftp://ftp.igsb.uiowa.edu/GIS_Library/IA_State/Hydrologic/Ground_Waters/ Mississippian_aquifer/mississippian_topography.zip. The URL for the thickness was ftp://ftp.igsb.uiowa.edu/GIS_Library/IA_State/Hydrologic/Ground_Waters/ Mississippian_aquifer/mississippian_isopach.zip Reference for the top map is Altitude and Configuration, in feet above mean sea level, of the Mississipian Aquifer modified from a scanned image of Map 1, Sheet 1, Miscellaneous Map Series 3, Mississippian Aquifer of Iowa by P.J. Horick and W.L. Steinhilber, Iowa Geological Survey, 1973; IGS MMS-3, Map 1, Sheet 1 Reference for the thickness map is Distribution and isopach thickness, in feet, of the Mississipian Aquifer, modified from a scanned image of Map 1, Sheet 2, Miscellaneous Map Series 3, Mississippian Aquifer of Iowa by P.J. Horick and W.L. Steinhilber, Iowa Geological Survey, 1973; IGS MMS-3, Map 1, Sheet 2 2. The altitude contours for the top and bottom of SA2 were digitized from georeferenced figures of altitude contours in U.S. Geological Survey Professional Paper 1305 (USGS PP1305), figure 6 (for the top surface) and figure 9 (for the bottom surface). The altitude contours for SA1 and SA2 were interpolated into surface rasters within a GIS using tools that create hydrologically correct surfaces from contour data, derive the altitude from the thickness (depth from the land surface), and merge the subareas into a single surface. The primary tool was an enhanced version of "Topo to Raster" used in ArcGIS, ArcMap, Esri 2014. ArcGIS Desktop: Release 10.2 Redlands, CA: Environmental Systems Research Institute. The raster surfaces were corrected in areas where the altitude of the top of the aquifer exceeded the land surface, and where the bottom of an aquifer exceeded the altitude of the corrected top of the aquifer.

This data set represents the extent of the Early Mesozoic basin aquifers in the states of Massachusettes, Connecticut, New York, New Jersey, Pennsylvania, Maryland, Virginia, and North Carolina.

From 2013 to 2018, the U.S. Geological Survey, in cooperation with the Town of Enfield and the Tompkins County Planning Department, studied the unconsolidated aquifers in the Enfield Creek Valley in the town of Enfield, Tompkins County, New York. The objective of this study was to characterize the hydrogeology and water quality of the unconsolidated aquifers in the Enfield Creek valley and produce a summary report of the findings. The spatial extent and hydrogeologic framework of these unconsolidated aquifers were delineated using existing data, including soils maps, well records, geologic logs, topographic data, and published reports. An interactive ArcGIS Online web map of the geospatial datasets is available here: https://usgs.maps.arcgis.com/home/webmap/viewer.html?webmap=b53518b0b6b74694932605c4578c00c3. These geospatial datasets support U.S. Geological Survey Scientific Investigations Report 2019-5136, "Geohydrology and Water Quality of the Unconsolidated Aquifers in the Enfield Creek Valley, Town of Enfield, Tompkins County, New York."

This data set represents the extent of the North Atlantic Coastal Plain aquifer system in North Carolina, Virginia, Maryland, Deleware, and New Jersey.

This geodatabase includes spatial datasets that represent the Southeastern Coastal Plain aquifer system in the States of Alabama, Georgia, Mississippi, South Carolina, and Tennessee. Included are: (1) polygon extents; datasets that represent the aquifer system extent, the entire extent subdivided into subareas or subunits, and any polygon extents of special interest (outcrop areas, no data available, areas underlying other aquifers, anomalies, for example), (2) raster datasets for the altitude of each aquifer subarea or subunit, (3) altitude, and/or if applicable, thickness contours used to generate the surface rasters, (4) georeferenced images of the figures that were digitized to create the altitude and thickness contours. The images and digitized contours are supplied for reference. The extent of the Southeastern Coastal Plain aquifer system is derived the linework in the Southeastern Coastal Plain aquifer system extent maps in a digital version of the aquifer extent presented in the Groundwater Atlas of the United States (the U.S. Geological Survey Hydrologic Atlas HA-730-F, -730-G, and -730-K. The Southeastern Coastal Plain aquifer system has 4 aquifer subunits, in order from the most surficial to the deepest: A1: Chickasawhay River aquifer, A2: Pearl River Aquifer, A3: Chattahoochee River Aquifer, and A4: Black Warrior River Aquifer. The altitude and thickness contours for each available subunit were digitized from georeferenced figures of altitude contours in U.S. Geological Survey Profession Paper 1410-B, (USGS PP 1410-B), and the resultant top and bottom altitude values were interpolated into surface rasters within a GIS using tools that create hydrologically correct surfaces from contour data, derive the altitude from the thickness (depth from the land surface), and merge the subareas into a single surface. The primary tool was "Topo to Raster" used in ArcGIS, ArcMap, Esri 2014. The surface rasters were corrected for the areas where the altitude of an underlying layer of the aquifer exceeded altitude of an overlying layer.

This dataset contains locations of aquifer boundaries and types of aquifer confinement.

This data set represents the extent of the Mississippian aquifers which is in the uppermost aquifer in Paleozoic rocks of northern Missouri.