This data set describes ground-water regions in the United States defined by the U.S. Geological Survey. These ground-water regions are useful for dividing the United States into areas of roughly similar hydrologic characterstics and water-use patterns. Most of these regions are very generalized and were developed from a illustration published at a scale of approximately 1:20 million. The data set also includes polygon features for unconsolidated watercourses taken from 1:7,500,000-scale U.S. Geological Survey map of productive aquifers.

This data set describes ground-water regions in the United States defined by the U.S. Geological Survey. These ground-water regions are useful for dividing the United States into areas of roughly similar hydrologic characterstics and water-use patterns. These regions are very generalized and were developed from a illustration published at a scale of approximately 1:20 million.

These data were released prior to the October 1, 2016 effective date for the USGS’s policy dictating the review, approval, and release of scientific data as referenced in USGS Survey Manual Chapter 502.8 Fundamental Science Practices: Review and Approval of Scientific Data for Release. Note that this data release has been modified from its original version. This data release was originally published on the U.S. Geological Survey (USGS) Water Mission Area NSDI Node (Node) in 2008. The Node has since been deprecated, and the data release was revised and, in 2023, the files were moved over to Sciencebase, which is a USGS trusted digital repository. When this migration of files initially took place, each unit extent and surface file for the Mississippi embayment aquifer system was given its own landing page. The 2025 version of this data release revised the 2023 revision. This 2025 version regrouped the extents, surfaces, and metadata files, presenting them on one Sciencebase landing page. A new master metadata file was compiled to document all the datasets and each surface altitude raster is presented in three formats: ASCII, GRID, and TIFF (a new format). The 2025 version of the data release was created to make the spatial data more accessible to the user and to simplify the ScienceBase catalog. The following list of Digital Object Identifiers (DOI) are from the 2023 revision pages and have been deprecated and superseded by this data release's DOI (doi:10.5066/P1VRSZLE). Deprecated DOIs: doi:10.5066/P913ILLC, doi:10.5066/P9PV92DD, doi:10.5066/P99DN2Q7, doi:10.5066/P90OQTTN, doi:10.5066/P97M18BU, doi:10.5066/P9TKXK1S, doi:10.5066/P9PEIHPU, doi:10.5066/P97WO9AD, doi:10.5066/P95QSYP9, doi:10.5066/P9OX7ATU, doi:10.5066/P9MMLD4I, doi:10.5066/P9QIJ2UX, doi:10.5066/P96ERE0X, doi:10.5066/P9OMYUX4, doi:10.5066/P9C2AXIZ, doi:10.5066/P913AT6B, doi:10.5066/P9VJ7FHM, doi:10.5066/P95UZ2X7, doi:10.5066/P9JHYMO3 This data release provides outcrop and subcrop extents and digital surfaces containing the top altitude of the following hydrogeologic units in Arkansas, Alabama, Louisiana, Missouri, Mississippi, and Tennessee. The abbreviations used for each hydrogeologic unit is listed below. These abbreviations are used in names of the data release files. Extent file names end in "_extent" and the raster file names end in "_surf". 1. alvm - Mississippi River Valley Alluvial Aquifer (extent only) 2. vkbg - Vicksburg-Jackson Group 3. ucaq - Upper Claiborne aquifer 4. mccu - Middle Claiborne confining unit 5. mcaq - Middle Claiborne aquifer 6. lccu - Lower Claiborne confining unit 7. lcaq - Lower Claiborne aquifer 8. mwaq - Middle Wilcox aquifer 9. lwaq - Lower Wilcox aquifer 10. mdwy - Midway confining unit The hydrogeologic unit surface datasets contain 414 rows and 394 columns representing 1-mile grid spacing. In general, limitations of data interpolation included areas of sparse geophysical log control points, log datums not clearly defined for some logs, unknown exact extent of each hydrogeologic unit in subcrop, interpolation limitations, and values averaged over 1-mile grid spacing. This data release contains data sets that characterize the Mississippi embayment aquifer system. These data sets were assembled as part of the Mississippi Embayment Regional Aquifer Study (MERAS) as described in the associated report (Hart, R.M., Clark, B.R., and Bolyard, S.E., 2008, Digital surfaces and thicknesses of selected hydrogeologic units within the Mississippi Embayment Regional Aquifer Study (MERAS): U.S. Geological Survey Scientific Investigations Report 2008-5098, 33 p.) and utilized in the MERAS groundwater-flow model (Clark, B.R., and Hart, R.M., 2009, The Mississippi Embayment Regional Aquifer Study (MERAS): Documentation of a groundwater-flow model constructed to assess water availability in the Mississippi Embayment: U.S. Geological Survey Scientific Investigations Report 2009-5172, 61 p.) A supplementary shapefile containing the extent of the MERAS

This digital data set describes productive aquifers in the conterminous United States. The data set was generated from a U.S. Geological Survey 1:7,500,000-scale map of productive aquifers of the conterminous United States.

The U.S. Geological Survey developed this dataset as part of the Colorado Front Range Infrastructure Resources Project (FRIRP). One goal of the FRIRP was to provide information on the availability of those hydrogeologic resources that are either critical to maintaining infrastructure along the northern Front Range or that may become less available because of urban expansion in the northern Front Range. This dataset extends from the Boulder-Jefferson County line on the south, to the middle of Larimer and Weld Counties on the North. On the west, this dataset is bounded by the approximate mountain front of the Front Range of the Rocky Mountains; on the east, by an arbitrary north-south line extending through a point about 6.5 kilometers east of Greeley. This digital geospatial dataset consists of saturated-thickness polygons that were generated with a Geographic Information System (GIS).

The U.S. Geological Survey developed this dataset as part of the Colorado Front Range Infrastructure Resources Project (FRIRP). One goal of the FRIRP was to provide information on the availability of those hydrogeologic resources that are either critical to maintaining infrastructure along the northern Front Range or that may become less available because of urban expansion in the northern Front Range. This dataset extends from the Boulder-Jefferson County line on the south, to the middle of Larimer and Weld Counties on the North. On the west, this dataset is bounded by the approximate mountain front of the Front Range of the Rocky Mountains; on the east, by an arbitrary north-south line extending through a point about 6.5 kilometers east of Greeley. This digital geospatial dataset consists of saturated-thickness polygons that were generated with a Geographic Information System (GIS).

The U.S. Geological Survey developed this dataset as part of the Colorado Front Range Infrastructure Resources Project (FRIRP). One goal of the FRIRP was to provide information on the availability of those hydrogeologic resources that are either critical to maintaining infrastructure along the northern Front Range or that may become less available because of urban expansion in the northern Front Range. This dataset extends from the Boulder-Jefferson County line on the south, to the middle of Larimer and Weld Counties on the North. On the west, this dataset is bounded by the approximate mountain front of the Front Range of the Rocky Mountains; on the east, by an arbitrary north-south line extending through a point about 6.5 kilometers east of Greeley. This digital geospatial dataset consists of depth-to-water (unsaturated-thickness) contours that were generated from hydrogeologic data with Geographic Information System (GIS) software.

The U.S. Geological Survey developed this dataset as part of the Colorado Front Range Infrastructure Resources Project (FRIRP). One goal of the FRIRP was to provide information on the availability of those hydrogeologic resources that are either critical to maintaining infrastructure along the northern Front Range or that may become less available because of urban expansion in the northern Front Range. This dataset extends from the Boulder-Jefferson County line on the south, to the middle of Larimer and Weld Counties on the North. On the west, this dataset is bounded by the approximate mountain front of the Front Range of the Rocky Mountains; on the east, by an arbitrary north-south line extending through a point about 6.5 kilometers east of Greeley. This digital geospatial dataset consists of bedrock-outcrop outlines from hand-drawn maps.

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."

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."