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Principal Aquifers of the United States, Puerto Rico and the U.S. Virgin Islands: Map Layer
Description File- unconsolidated deposits of sand and gravel,Glacial deposits that contain numerous productive aquifers and major alluvial aquifers along main watercourses north of the limit of continental glaciation are included as a separate map layer of this Atlas.
- semiconsolidated sand
- sandstone
- carbonate rocks
- interbedded sandstone and carbonate rocks
- igneous and metamorphic rocks
The Ground Water Atlas of the United States describes the location, the extent, and the geologic and hydrologic characteristics of the important aquifers of the Nation.
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The areal extent of the aquifers, as shown in this data set, represents the area in which a named aquifer is the shallowest of the principal aquifers. These aquifer areas are not necessarily the only areas in which ground water can be withdrawn, for two reasons: 1) The aquifers shown may have a larger areal extent than is represented here. The boundaries in this data set generally represent an interpretation of the surface location (outcrop), or near-surface location (shallow subcrop) of the uppermost principal aquifer for the area. An aquifer may extend beyond the area shown, but be overlain by one or more other aquifers, and (or) low-permeability material. 2) There may be areas of water-bearing surficial material not shown in this data set. Major alluvial aquifers that occur along main watercourses are not shown. Significant unconsolidated sand and gravel aquifers, that are not indicated in this data set but are important sources of water, may occur locally in glaciated regions. The user of this data set is advised that to get complete information regarding areas that serve as sources of water, more information about surficial aquifers needs to be obtained, particularly in glaciated areas.
This data set was constructed by combining data created for or from the regional GWA chapters. Minor aquifers that are important local sources of water were mapped in some regions, so the regional maps in the GWA may show more detail than this data set. The data were reviewed, adjusted, and published based on new information provided by national, State, and local scientists. The juxtaposition of regionally mapped aquifers has led to some instances where an aquifer outcrop or shallow subcrop is bounded by a State line. This is a result of the regional mapping and national categorization methods used and is not meant to imply a hydrogeologic change coincident with a State boundary.
The aquifer outcrop and shallow subcrop boundaries represent broad, regional categories and should not be interpreted as site-specific. Comments regarding the names of aquifers or the hydrogeologic interpretation of the aquifers can be directed to the U.S. Geological Survey, Water Resources Division, Office of Ground Water, ogw_webmaster@usgs.gov.
This data set was used as part of the effort to publish a 1:5,000,000- scale 'Principal Aquifers' map in the National Atlas of the United States of America series of printed maps. The printed map can be considered a representation of this data set with the exceptions of: the smaller scale, slight differences in the coastline due to generalization, base and cultural information, and delineation of the glacial-deposit area.
These data were developed in conjunction with the publication of the GWA. For documentation purposes, areas are referred to by their corresponding GWA chapter letter, or by State. This list shows the relationship between State names and GWA chapters:
HA 730-B Segment 1-California, Nevada
HA 730-C Segment 2-Colorado, Utah, New Mexico, Arizona
HA 730-D Segment 3-Kansas, Missouri, Nebraska
HA 730-E Segment 4-Texas, Oklahoma
HA 730-F Segment 5-Arkansas, Louisiana, Mississippi
HA 730-G Segment 6-Alabama, Florida, Georgia, South Carolina
HA 730-H Segment 7-Idaho, Oregon, Washington
HA 730-I Segment 8-Montana, North Dakota, South Dakota, Wyoming
HA 730-J Segment 9-Iowa, Michigan, Minnesota, Wisconsin
HA 730-K Segment 10-Illinois, Indiana, Kentucky, Ohio, Tennessee
HA 730-L Segment 11-Delaware, Maryland, New Jersey, North
Carolina, Pennsylvania, Virginia, West
Virginia
HA 730-M Segment 12-Connecticut, Maine, Massachusetts, New
Hampshire, New York, Rhode Island, Vermont
HA 730-N Segment 13-Alaska, Hawaii, Puerto Rico, and the U.S.
Virgin Islands
Refer to <http://capp.water.usgs.gov/gwa/gwa.html> for a graphic depiction
of the GWA chapter regions, as well as more information about the GWA.
It may be helpful to refer to the printed GWA chapters when using the Data, however, there are significant differences between this national data set and the printed chapters. Because the GWA regional chapters were written by different authors, there were areas of different interpretations and category delineations, aquifer names, etc., that became apparent when combining the regions.
The following listings show the differences between aquifer names in the GWA chapters and the aq_name and aq_code used in this data set. See the Entity and Attribute Information section for definitions of the data attributes.
GWA chapter HA 730-B
Name from fig 11, page B4 aq_code-aq_name
____________________________________________________________
Basin and Range volcanic- 601-Southern Nevada
rock aquifers volcanic-rock aquifers
Coastal Basins aquifers 103-California Coastal Basin
aquifers
Northern California Basin 104-Pacific Northwest
fill aquifers basin-fill aquifers
GWA chapter HA 730-C
Name from fig 11, page C4
____________________________________________________________
Names and categories the same
GWA chapter HA 730-D
Name from fig 5, page D4 aq_code-aq_name
____________________________________________________________
Mississippi embayment 109-Mississippi River Valley
aquifer system alluvial aquifer
Great Plains aquifer 304-Lower Cretaceous
aquifers
Confining unit 999-Other rocks
Dune sand 107-High Plains aquifer
GWA chapter HA 730-E
Name from fig 4, page E3 aq_code-aq_name
____________________________________________________________
EDWARDS-TRINITY AQUIFER SYSTEM
Edwards-Trinity aquifer 501-Edwards-Trinity aquifer
system
Edwards aquifer 501-Edwards-Trinity aquifer
system
Trinity aquifer 501-Edwards-Trinity aquifer
system
Confining unit 999-Other rocks
GWA chapter HA 730-F
Name from fig 7, page 4 aq_code-aq_name
____________________________________________________________
MAJOR AQUIFER SYSTEMS
Surficial aquifer system 109-Mississippi River Valley
alluvial aquifer
203-Mississippi embayment
aquifer system
501-Edwards-Trinity aquifer
system
999-Other rocks
Mississippi embayment 109-Mississippi River Valley
aquifer system alluvial aquifer
203-Mississippi embayment
aquifer system
204-Southeastern Coastal
Plain aquifer system
999-Other rocks
Tokio-Woodbine aquifer 999-Other rocks
Ouachita Mountains aquifer 999-Other rocks
CONFINING SYSTEMS AND CONFINING UNITS
Western Interior Plains 999-Other rocks
confining systems
Confining unit 109-Mississippi River Valley
alluvial aquifer
203-Mississippi embayment
aquifer system
999-Other rocks
GWA chapter HA 730-G
Name from fig 3, page 3 aq_code-aq_name
____________________________________________________________
Sand and gravel aquifer 201-Coastal lowlands aquifer
system
Piedmont and Blue Ridge 611-Piedmont and Blue Ridge
aquifers crystalline-rock aquifers
Appalachian Plateaus 310-Pennsylvanian aquifers
aquifers
Interior Low Plateaus 503-Mississippian aquifers
aquifers
Confining unit 999-Other rocks
GWA chapter HA 730-H
Name from fig 5, page H4 aq_code-aq_name
____________________________________________________________
Unconsolidated-deposit 101-Basin and Range basin-fill
aquifers aquifers
104-Pacific Northwest
basin-fill aquifers
105-Northern Rocky Mountains
Intermontane Basins
aquifer system
112-Puget Sound aquifer system
Pliocene and younger 606-Snake River Plain
basaltic-rock aquifers basaltic-rock aquifers
610-Pacific Northwest
basaltic-rock aquifers
Miocene basaltic-rock 606-Snake River Plain
aquifers basaltic-rock aquifers
607-Columbia Plateau basaltic-rock
aquifers
610-Pacific Northwest
basaltic-rock aquifers
Aquifers in pre-Miocene 401-Basin and Range
rocks carbonate-rock aquifers
999-Other rocks
GWA chapter HA 730-I. See Process Description regarding
differences between this data and the printed Ground Water
Atlas chapter in Western Montana
Name from fig 7, page I4 aq_code-aq_name
____________________________________________________________
Quaternary volcanic and 610-Pacific Northwest
sedimentary rock aquifers basaltic-rock aquifers
Upper Tertiary aquifers 105-Northern Rocky Mountains
Intermontane Basins
aquifer system
107-High Plains aquifer
314-Lower Tertiary aquifers
316-Wyoming Tertiary aquifers
Lower Tertiary aquifers 107-High Plains aquifer
314-Lower Tertiary aquifers
Upper Cretaceous aquifers 301-Colorado Plateaus
aquifers
315-Upper Cretaceous
aquifers
Lower Cretaceous aquifers 301-Colorado Plateaus
aquifers
304-Lower Cretaceous aquifers
Confining unit 301-Colorado Plateaus
aquifers
GWA chapter HA 730-J
Name from fig 7, page J4 aq_code-aq_name
____________________________________________________________
Cretaceous aquifer 304-Lower Cretaceous
aquifers
MISSISSIPPIAN AQUIFER
Carbonate rocks 503-Mississippian aquifers
Sandstone 311-Marshall aquifer
Crystalline-rock aquifer 999-Other rocks
Confining unit 312-Cambrian-Ordovician
aquifer system
999-Other rocks
GWA chapter HA 730-K
Name from fig 5, page K4 aq_code-aq_name
____________________________________________________________
Blue Ridge aquifers 611-Piedmont and Blue Ridge
crystalline-rock aquifers
MISSISSIPPI EMBAYMENT AQUIFER SYSTEM
Upper Claiborne, middle 109-Mississippi River Valley
Claiborne, middle Wilcox, alluvial aquifer
and lower Wilcox 203-Mississippi embayment
aquifer system
McNairy-Nacatoch 204-Southeastern Coastal
Plain aquifer system
Pennsylvanian aquifers 999-Other rocks
Confining unit 999-Other rocks
GWA chapter HA 730-L
Name from fig 7, page L4 aq_code-aq_name
____________________________________________________________
NORTHERN ATLANTIC COASTAL PLAIN AQUIFER SYSTEM
Surficial aquifer 111-Surficial aquifer system
205-Northern Atlantic
Coastal Plain aquifer
system
Chesapeake aquifer 205-Northern Atlantic
Coastal Plain aquifer
system
Castle Hayne-Aquia aquifer 418-Castle Hayne aquifer
Severn-Magothy aquifer 205-Northern Atlantic
Coastal Plain aquifer
system
Peedee-upper Cape Fear 205-Northern Atlantic
aquifer Coastal Plain aquifer
system
Potomac aquifer 205-Northern Atlantic
Coastal Plain aquifer
system
PIEDMONT AND BLUE RIDGE AQUIFERS
Aquifers in early Mesozoic 308-Early Mesozoic basin
basins aquifers
Carbonate-rock aquifers 417-Piedmont and Blue Ridge
carbonate-rock aquifers
Crystalline-rock aquifers 611-Piedmont and Blue Ridge
crystalline-rock aquifers
Valley and Ridge 416-New York and New England
carbonate-rock aquifers carbonate-rock aquifers
505-Valley and Ridge
carbonate-rock aquifers
APPALACHIAN PLATEAUS
Permian and Pennsylvanian 310-Pennsylvanian aquifers
aquifers
Not a principal aquifer 611-Piedmont and Blue Ridge
crystalline-rock aquifers
GWA chapter HA 730-M
Name from fig 10, page M5 aq_code-aq_name
____________________________________________________________
SANDSTONE AQUIFERS
Mesozoic sandstone and 308-Early Mesozoic basin
basalt of the Newark aquifers
Supergroup
Lower Paleozoic 309-New York sandstone
aquifers
CRYSTALLINE-ROCK AQUIFERS
Adirondack 999-Other rocks
GWA chapter HA 730-N
Hawaii name from fig 35,
page N14
Puerto Rico name from
fig 71, page N24 aq_code-aq_name
____________________________________________________________
Volcanic rock aquifers 608-Hawaiian Volcanic-rock
aquifers
609-Hawaiian Sedimentary
deposit aquifers
MINOR AQUIFERS
Coastal embayment aquifers 999-Other rocks
Volcaniclastic-, igneous-,
and sedimentary-rock aquifers
Confining unit 999-Other rocks
NORTHCOAST LIMESTONE AQUIFER SYSTEM
Upper aquifer 419-Puerto Rico North Coast Limestone
aquifer system
Lower aquifer 419-Puerto Rico North Coast Limestone
aquifer system
Related Spatial and Tabular Data Sets
A data set showing the areal extent of sand and gravel aquifers of alluvial and glacial origin north of the line of Quaternary continental glaciation is included in the online, interactive National Atlas of the United States. This data set ends at the southern limit of glaciation in the United States; areas north of the limit line contain significant sand and gravel glacial deposits that are important sources of water for local areas.
For additional information on principal aquifers, please see the Aquifer Basics page at <http://capp.water.usgs.gov/aquiferBasics/index.html>.
The final data are being served to the public in the following formats: Spatial Data Transfer Standard (SDTS), Arc/INFO Export, or ArcView Shapefile.
The Arc/INFO coverages were plotted and checked against the source compilations. Polygons were attributed using Arcedit. The coverages for GWA chapters HA 730-B, -C, -D, -E, -F, -I, -K, -L, and -M were used to generate output files that were imported into Adobe Illustrator for map publication. Each completed map, at a scale of 1:2,500,000, was reviewed for content and accuracy by the chapter lead cartographer, Water Resources Discipline Geohydrologic Map Editor, and chapter author.
Individual chapter coverages were appended into one continuous coverage. Arcedit was used for edgematching and to remove duplicate labels. No DISSOLVE was done on the coverage; an equivalent of a DISSOLVE was done manually in Arcedit in conjunction with attribute checking, by removing arcs that divided adjacent polygons with the same attributes. Several iterations of editing were performed. These mostly involved ensuring all polygons had labels and aquifer information and ensuring polygons had correct aquifer information. No polygons were removed for generalization.
Coastline Location
The 1:2,500,000 principal aquifer maps in the Ground Water Atlas publications used a coastline and international boundary, derived either from the map separates from the National Atlas of the United States of America (published 1970), or from the Digital Line Graph (DLG) data created from the 1970 National Atlas. GWA chapters HA 730-G, -J, and -H used coastline and boundary filmwork photo-mechanically reduced from the 1:2,000,000 National Atlas map separates. The remaining chapters used coastline and boundary data from the DLG's. A revision of the DLG data took place in 1997, after the creation of the chapter aquifer map data.
After the edgematching, a decision was made to replace the coast and international boundary of this national-level aquifer data with one derived from a newer version of 1997 DLG data. State boundary data from the National Atlas was used to provide the coastline and two aquifer boundaries that coincide with State lines.
The existing outline (coastline and international boundary line) was removed, the new outline added to the coverage, and the remaining aquifer contact lines snapped to the new outline. The coverage was re- cleaned, data categories checked onscreen and with plots, and corrected. Line and labeling corrections, such as undershoots, overshoots, and improper labels were corrected in Arcedit.
There are some slight locational differences between this data set and the printed GWA chapters. For example, there are several small differences in the number of small islands in coastal areas and the categorization of these small islands was assigned to either the nearby principal aquifer category or as Not a principal aquifer, depending on the location and categorization of similar small islands in the printed GWA chapters. There are other differences in the categorization of some land/shoreline-related features. For example, an area symbolized as a bay in a GWA chapter may be land in this data set.
Western Montana
During the review of a printed map made from this national-level aquifer data, the compiler, James A. Miller, requested a change in the representation of aquifers in western Montana. The area affected is in the following counties: Lincoln, Flathead, Sanders, Lake, Mineral, Missoula, Powell, Ravalli, Granite, Lewis and Clark, Deer Lodge, Silver Bow, Jefferson, Broadwater, Gallatin, Beavershead, and Madison. These areas fall under the Northern Rocky Mountain Intermontane Basins Regional Aquifer Systems Analysis (RASA). With one exception, the aquifers, as shown in GWA chapter I, figure 7 in the listed counties were removed and replaced with unconsolidated-deposit areas as shown in GWA chapter HA 730-I, figure 6. The exception is an area in northern Flathead county, listed as an Upper Tertiary aquifer in GWA chapter I, figure 7, that was retained as an area but reclassified as a Lower Tertiary aquifer.
aq_code -- aq_name
101 -- Basin and Range basin-fill aquifers
102 -- Rio Grande aquifer system
103 -- California Coastal Basin aquifers
104 -- Pacific Northwest basin-fill aquifers
105 -- Northern Rocky Mountains Intermontane Basins aquifer system
106 -- Central Valley aquifer system
107 -- High Plains aquifer
108 -- Pecos River Basin alluvial aquifer
109 -- Mississippi River Valley alluvial aquifer
110 -- Seymour aquifer
111 -- Surficial aquifer system
112 –- Puget Sound aquifer system
114 –- Puerto Rico south coast aquifer
115 –- Willamette Lowland basin-fill aquifers
116 –- Columbia Plateau basin-fill aquifers
117 –- Snake River Plain basin-fill aquifers
201 -- Coastal lowlands aquifer system
202 -- Texas coastal uplands aquifer system
203 -- Mississippi embayment aquifer system
204 -- Southeastern Coastal Plain aquifer system
205 -- Northern Atlantic Coastal Plain aquifer system
301 -- Colorado Plateaus aquifers
302 -- Denver Basin aquifer system
304 -- Lower Cretaceous aquifers
305 -- Rush Springs aquifer
306 -- Central Oklahoma aquifer
307 -- Ada-Vamoosa aquifer
308 -- Early Mesozoic basin aquifers
309 -- New York sandstone aquifers
310 -- Pennsylvanian aquifers
311 -- Marshall aquifer
312 -- Cambrian-Ordovician aquifer system
313 -- Jacobsville aquifer
314 -- Lower Tertiary aquifers
315 -- Upper Cretaceous aquifers
316 –- Wyoming Tertiary aquifers
401 -- Basin and Range carbonate-rock aquifers
402 -- Roswell Basin aquifer system
405 -- Ozark Plateaus aquifer system
406 -- Blaine aquifer
407 -- Arbuckle-Simpson aquifer
410 -- Silurian-Devonian aquifers
411 -- Ordovician aquifers
412 -- Upper carbonate aquifer
413 -- Floridan aquifer system
414 -- Biscayne aquifer
416 -- New York and New England carbonate-rock aquifers
417 -- Piedmont and Blue Ridge carbonate-rock aquifers
418 -- Castle Hayne aquifer
419 –- Puerto Rico North Coast Limestone aquifer system
420 -– Kingshill aquifer
501 -- Edwards-Trinity aquifer system
502 -- Valley and Ridge aquifers
503 -- Mississippian aquifers
504 -- Paleozoic aquifers
505 -- Valley and Ridge carbonate-rock aquifers
601 -- Southern Nevada volcanic-rock aquifers
606 -- Snake River Plain basaltic-rock aquifers
607 -- Columbia Plateau basaltic-rock aquifers
608 -- Hawaiian Volcanic-rock aquifers
609 –- Hawaiian Sedimentary deposit aquifers
610 -– Pacific Northwest basaltic-rock aquifers
611 -– Piedmont and Blue Ridge crystalline-rock aquifers
999 –- Other rocks. Rocks that are generally poorly permeable but
locally may contain productive aquifers.