Hydrogeologic provinces of the conterminous United States

This data release contains shapefiles of the hydrogeologic provinces of the conterminous United States. The United States Geological Survey (USGS) is developing a National Extent Hydrogeologic Framework (NEHF). In support of that effort, the conterminous United States was subdivided into eight hydrogeologic provinces that are generally based on geologic provinces and subprovinces previously defined in USGS Circular 1300 (Reed and Bush, 2007). Two of the eight hydrogeologic provinces were subdivided into subprovinces. The boundaries of the polygons, representing the hydrogeologic provinces and subprovinces, were largely based on the boundaries of geologic map units and faults of the Geologic Map of North America (GMNA, Garrity and Soller, 2009). In areas where a hydrogeologic province or subprovince boundary was not closely approximately by a GMNA boundary, the extents of principal aquifers (USGS, 2003) were used as a guide. The hydrogeologic provinces identify areas that generally consist of rocks and sediment of similar geologic age, lithology, and degree of deformation; these characteristics are generally related to the hydrologic properties of subsurface aquifers and confining layers.

References cited:

Garrity, C.P., and Soller, D.R., 2009, Database of the geologic map of North America; adapted from the map by J.C. Reed, Jr. and others (2005): U.S. Geological Survey Data Series 424, accessed June 11, 2025, at https://pubs.usgs.gov/ds/424/.

Reed, J.C., and Bush, C.A., 2007, About the geologic map in the National Atlas of the United States of America: U.S. Geological Survey Circular 1300, 52 p., accessed on June 12, 2025, at https://doi.org/10.3133/cir1300.

U.S. Geological Survey, 2003, Principal aquifers of the 48 conterminous United States, Hawaii, Puerto Rico, and the U.S. Virgin Islands: U.S. Geological Survey data release, accessed June 12, 2025, at https://doi.org/10.5066/P9Y2HOUJ.