USGS 19980701 Version 1.0 vector digital data Madison, Wisconsin, USA U.S. Geological Survey http://nationalatlas.gov/atlasftp.html aquifrp025 This data set contains the shallowest principal aquifers of the conterminous United States, portrayed as polygons. The data set was developed as part of the effort to produce the maps published at 1:2,500,000 in the printed series "Ground Water Atlas of the United States". The published maps contain base and cultural features not included in these data. This data set was previously called Principal Aquifers of the 48 Contiguous United States. These data are intended for use in publications, at a scale of 1:2,500,000 or smaller. Due to the small scale, the primary intended use is for regional and national data display and analysis, rather than specific local data analysis. The Ground Water Atlas of the United States (GWA) chapters include additional information that may be relevant to the use of this data set, such as maps of alluvial and glacial aquifers that overlie the aquifers in this data set, as well as other information described below. 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 These aquifer areas are not necessarily the only areas in which ground water can be withdrawn, for two reasons: 1) The aquifers shown may have a larger areal extent than is represented here.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 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, Roy Sonenshein, sunshine@usgs.gov, (305) 717-5824. 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 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. Although these spatial data can stand alone, it may be helpful to refer to the printed GWA chapters when using the data. There are three subject areas in which there are significant differences between this data set and the printed chapters: category changes, which are described below; coastline location, and the representation of aquifers in Western Montana, both of which are discussed in the Process Description under Lineage. Category Changes 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. In most cases, the name and delineation of the aquifer is identical between this data set and the GWA printed maps, but there are several areas of differences. In some cases, a single aquifer from a GWA chapter is represented among multiple aquifers in this data set. 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 system > >Confining unit 999-Not a principal aquifer > >Not a principal aquifer 999-Not a principal aquifer > >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-Not a principal aquifer > > >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-Not a principal aquifer > >Mississippi embayment 109-Mississippi River Valley >aquifer system alluvial aquifer > 203-Mississippi embayment > aquifer > 204-Southeastern Coastal > Plain aquifer system > 999-Not a principal aquifer > >MINOR AQUIFERS AND AQUIFER SYSTEMS - Aquifer systems in >rocks of cretaceous age >Edwards-Trinity aquifer 501-Edwards-Trinity aquifer >system (Trinity aquifer) system > >Tokio-Woodbine aquifer 999-Not a principal aquifer > >Ouachita Mountains aquifer 999-Not a principal aquifer > >CONFINING SYSTEMS AND CONFINING UNITS >Western Interior Plains 999-Not a principal aquifer >confining systems > >Confining unit 109-Mississippi River Valley > alluvial aquifer > 203-Mississippi embayment > aquifer system > 999-Not a principal aquifer > > >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 999-Not a principal aquifer >aquifers > >Appalachian Plateaus 310-Pennsylvanian aquifers >aquifers > >Interior Low Plateaus 503-Mississippian aquifers >aquifers > >Confining unit 999-Not a principal aquifer > > >GWA chapter HA 730-H >Name from fig 5, page H4 aq_code-aq_name >____________________________________________________________ >Unconsolidated-deposit 104-Pacific Northwest >aquifers basin-fill aquifers > 112-Puget-Willamette Lowland > aquifer system > 105-Northern Rocky Mountains > Intermontane basins > aquifer system > 101-Basin and Range aquifers > >Pliocene and younger 603-Pliocene and younger >basaltic-rock aquifers basaltic-rock aquifers > 606-Snake River Plain > aquifer system > >Miocene basaltic-rock 607-Columbia Plateau aquifer >aquifers system > 604-Miocene basaltic-rock > aquifers > >Aquifers in pre-Miocene 401-Basin and Range >rocks carbonate-rock aquifers > 999-Not a principal aquifer > > >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 605-Volcanic and >sedimentary rock aquifers sedimentary-rock > aquifers > >Upper Tertiary aquifers 107-High Plains aquifer > 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 aquifer > >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-Mississippian aquifers > of Michigan > >Crystalline-rock aquifer 999-Not a principal aquifer > >Confining unit 999-Not a principal aquifer > > >GWA chapter HA 730-K >Name from fig 5, page K4 aq_code-aq_name >____________________________________________________________ >Blue Ridge aquifers 308-Early Mesozoic basin > aquifers > 999-Not a principal aquifer > >MISSISSIPPI EMBAYMENT AQUIFER SYSTEM >Upper Claiborne, middle 203-Mississippi embayment >Claiborne, middle Wilcox, aquifer system >and lower Wilcox 109-Mississippi River Valley > alluvial aquifer > >McNairy-Nacatoch 204-Southeastern Coastal > Plain aquifer system > >Confining unit 999-Not a principal aquifer > > >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 > >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 999-Not a principal aquifer > >Valley and Ridge 505-Valley and Ridge >carbonate-rock aquifers carbonate-rock aquifers > 416-New York and New England > carbonate-rock aquifers > >APPALACHIAN PLATEAUS >Permian and Pennsylvanian 310-Pennsylvanian aquifers >aquifers > > >GWA chapter HA 730-M >Name from fig 10, page M5 aq_code-aq_name >____________________________________________________________ >CARBONATE-ROCK AQUIFERS >New York and New England 416-New York and New England > carbonate-rock aquifers > >Valley and Ridge 416-New York and New England > carbonate-rock aquifers > >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-Not a principal aquifer > >New England 999-Not a principal aquifer > > Related Spatial and Tabular Data Sets A data set showing the extent of glacial deposits is included in the online, interactive National Atlas of the United States, but is not available to download. This data set shows the southern limit of glaciation in the United States; areas north of the limit line may containsignificant sand and gravel glacial deposits that are important sources of water for local areas. A data set of aquifers of Alaska is in work. A data set of aquifers of Puerto Rico and the U.S. Virgin Islands is in work. A data set of aquifers of Hawaii is planned. The final data are being served to the public in the following formats: Spatial Data Transfer Standard (SDTS), Arc/INFO Export, or ArcView Shapefile. en 19980701 publication date Complete As needed -124.755791 -66.939561 49.385619 24.518322 -124.755791-66.93956124.51832249.385619 None Aquifer Groundwater Hydrogeology Geohydrology MEAR181 None Alabama Arizona Arkansas California Colorado Connecticut Delaware District of Columbia Florida Georgia Idaho Illinois Indiana Iowa Kansas Kentucky Louisiana Maine Maryland Massachusetts Michigan Minnesota Mississippi Missouri Montana Nebraska Nevada New Hampshire New Jersey New Mexico New York North Carolina North Dakota Ohio Oklahoma Oregon Pennsylvania Rhode Island South Carolina South Dakota Tennessee Texas Utah Vermont Virginia Washington West Virginia Wisconsin Wyoming United States None None. Acknowledgment of the Ground Water Atlas of the United States and (or) the National Atlas of the United States of America would be appreciated in products derived from these data. U.S. Geological Survey Chief, Cartographic and Publications Program, Water Resources Division mailing and physical address

505 Science Drive

Madison WI 53711-1061 USA 608-238-9333 This data set was created and modified over a period of at least five years by several staff members of the U.S. Geological Survey Water Resources Division Cartographic and Publications Program in Madison, Wisconsin. Completion of this data set and associated metadata was funded, in part, under a cooperative joint funding agreement between the U.S. Geological Survey and the U.S. Environmental Protection Agency. Microsoft Windows 2000 Version 5.1 (Build 2600) Service Pack 1; ESRI ArcCatalog 8.3.0.800 Shapefile Polygon and chain-node topology are present. Each polygon is closed and has one label point. This data set includes aquifer information for the 48 conterminous United States and the District of Columbia. Planert, M. (comp.) Williams, J.S. (comp.) 1995 1.0 map Hydrologic Investigations Atlas HA 730-B Reston, VA U.S. Geological Survey 2500000 stable-base material 1995 publication date GWA HA 730-B Aquifer data for California and Nevada Robson, S.G. (comp.) Banta, E.R. (comp.) 1995 1.0 Map Hydrologic Investigations Atlas HA 730-C Reston, VA U.S. Geological Survey 2500000 Stable-base material 1995 Publication date GWA HA 730-C Aquifer data for Arizona, Colorado, New Mexico, and Utah Miller, J.A. (comp.) Appel, C.L. (comp.) 1998 1.0 Map Hydrologic Investigations Atlas HA 730-D Reston, VA U.S. Geological Survey 2500000 Stable-base material 1998 Publication date GWA HA 730-D Aquifer data for Kansas, Missouri, and Nebraska Ryder, P.D. (comp.) 1996 1.0 Map Hydrologic Investigations Atlas HA 730-E Reston, VA U.S. Geological Survey 2500000 Stable-base material 1996 Publication date GWA HA 730-E Aquifer data for Oklahoma and Texas Renken, R.A. (comp.) 1998 1.0 Map Hydrologic Investigations Atlas HA 730-F Reston, VA U.S. Geological Survey 2500000 Stable-base material 1998 Publication date GWA HA 730-F Aquifer data for Arkansas, Louisiana, and Mississippi Miller, J.A. (comp.) 1990 1.0 Map Hydrologic Investigations Atlas HA 730-G Reston, VA U.S. Geological Survey 2500000 Stable-base material 1990 Publication date GWA HA 730-G Aquifer data for Alabama, Florida, Georgia, and South Carolina Whitehead, R.L. (comp.) 1994 1.0 Map Hydrologic Investigations Atlas HA 730-H Reston, VA U.S. Geological Survey 2500000 Stable-base material 1994 Publication date GWA HA 730-H Aquifer data for Idaho, Oregon, and Washington Whitehead, R.L. (comp.) 1996 1.0 Map Hydrologic Investigations Atlas HA 730-I Reston, VA U.S. Geological Survey 2500000 Stable-base material 1996 Publication date GWA HA 730-I Aquifer data for Montana, North Dakota, South Dakota, and Wyoming Olcott, P.G. (comp.) 1992 1.0 Map Hydrologic Investigations Atlas HA 730-J Reston, VA U.S. Geological Survey 2500000 Stable-base material 1992 Publication date GWA HA 730-J Aquifer data for Iowa, Michigan, Minnesota, and Wisconsin Lloyd, O.B., Jr. (comp.) Lyke, W.L. (comp.) 1995 1.0 Map Hydrologic Investigations Atlas HA 730-K Reston, VA U.S. Geological Survey 2500000 Stable-base material 1995 Publication date GWA HA 730-K Aquifer data for Illinois, Indiana, Kentucky, Ohio, and Tennessee Trapp, H., Jr. (comp.) Horn, M.A. (comp.) 1997 1.0 Map Hydrologic Investigations Atlas HA 730-L Reston, VA U.S. Geological Survey 2500000 Stable-base material 1997 Publication date GWA HA 730-L Aquifer data for Delaware, Maryland, New Jersey, North Carolina, Pennsylvania, Virginia, and West Virginia Olcott, P.G. (comp.) 1995 1.0 Map Hydrologic Investigations Atlas HA 730-M Reston,VA U.S. Geological Survey 2500000 Stable-base material 1995 Publication date GWA HA 730-M Aquifer data for Connecticut, Maine, Massachusetts, New Hampshire, New York, Rhode Island, and Vermont United States Geological Survey 1998 Map Reston,VA U.S. Geological Survey <http://nationalatlas.gov/atlasftp.html> 2000000 Online 1997 Publication date DLG State boundaries Coastline and international boundary U.S. Geological Survey, Water Resources Division Unpublished material Map 2500000 Internal file 1990 1993 Publication or compilation date National aquifers file Preliminary aquifer map of the 48 conterminous States. Aquifer outcrop line work for each GWA chapter was compiled on mylar at a scale of 1:2,000,000, and reduced to 1:2,500,000 for further production work. For chapters HA 730-G, -H, and -J, the outcrop lines were scribed at a line width of 0.006 inch. Film positives made from the scribed materials were scanned on a drum scanner, vectorized, and converted to Arc/INFO coverages. For chapters HA 730-B, -C, -D, -E, -F, -I, -K, -L, and -M, the aquifer compilation was either hand digitized, and (or) scanned on a drum scanner, vectorized and converted to Arc/INFO coverages. The data were then checked, cleaned up, and attribute creation was done. 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 Division 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. HA 730-B HA 730-C HA 730-D HA 730-E HA 730-F HA 730-G HA 730-H HA 730-I HA 730-J HA 730-K HA 730-L HA 730-M 1993 National aquifers file Plots of the national aquifers file were made at 1:2,500,000, covering the areas of the regional GWA chapters. Each plot was compared to the printed GWA chapter aquifer maps. Where applicable (chapters HA 730-B, -C, -D, -E, -F, -I, -K, - L, and -M), an Adobe Illustrator file of the coverage data was compared on-screen with the Illustrator file used to print the published map. Discrepancies between the coverage file and print file were noted, and the coverage updated to match the published map. Where a line appeared to shift noticeably (approximately 1/8 inch at a scale of 1:2,500,000) across the boundary of two adjacent GWA chapter regions, the line was adjusted for a smoother appearance. The adjustments may have been made on one or both sides of the regionboundary, depending on a cartographic assessment of the instance. 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 U.S. Geological Survey National Mapping Division was used to provide the coastline and two aquifer boundaries that coincide with State lines. A publicly available version of this data and its metadata (Map Layer Theme States) can be found at http://nationalatlas.gov/atlasftp.html. 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. National aquifer file HA 730-B HA 730-C HA 730-D HA 730-E HA 730-F HA 730-G HA 730-H HA 730-I HA 730-J HA 730-K HA 730-L HA 730-M DLG State boundaries 1997 Vector G-polygon 4276 Complete chain 6802 GT-polygon composed of chains 4276 SimplePolygonFALSE4276FALSEFALSE 0.000001 0.000001 Decimal degrees North American Datum of 1983 Geodetic Reference System 80 6378137.000000 298.257222 GCS_North_American_1983 aquifrp025 A formation, group of formations, or part of a formation that contains sufficient saturated permeable material to yield significant quantities of water to wells and springs. U.S. Geological Survey Feature Class4276 FID Internal feature number. ESRI Polygon 2-dimensional element. ESRI GIS software Sequential unique whole numbers that are automatically generated. FIDOID400 Shape Feature geometry. ESRI 0.00000 56.31950 Coordinates defining the features. ShapeGeometry000 AREA The perimeter of the shape in coverage units. U.S. Geological Survey 0.01024 606.75187 AREANumber185 PERIMETER Internal feature number. U.S. Geological Survey 2 4277 PERIMETERNumber185 AQUIFRP025 User-assigned feature number. U.S. Geological Survey 1 4276 AQUIFRP025Number11 ROCK_NAME The name of the permeable geologic material that composes the aquifer. U.S. Geological Survey unconsolidated sand and gravel aquifers Formations composed of loose sand and gravel. U.S. Geological Survey semiconsolidated sand aquifers Formations composed of partially solidified sand. U.S. Geological Survey sandstone aquifers Formations composed of sandstone. U.S. Geological Survey Carbonate-rock aquifers Formations composed of limestone and (or) dolomite. U.S. Geological Survey Sandstone and carbonate-rock aquifers Formations composed of sandstone, limestone, and (or) dolomite. U.S. Geological Survey Basalt and other volcanic-rock aquifers Formations composed of volcanic rocks. U.S. Geological Survey (blank field) Not a principal aquifer. Rocks that are generally poorly permeable but locally may contain productive aquifers. U.S. Geological Survey ROCK_NAMEString45 ROCK_TYPE The code number relating to the rock_name. U.S. Geological Survey 0 Null value, assigned to null polygon. U.S. Geological Survey 100 Number for unconsolidated sand and gravel aquifers. U.S. Geological Survey 200 Number for semiconsolidated sand aquifers. U.S. Geological Survey 300 Number for sandstone aquifers. U.S. Geological Survey 400 Number for carbonate-rock aquifers. U.S. Geological Survey 500 Number for sandstone and carbonate-rock aquifers. U.S. Geological Survey 600 Number for basalt and other volcanic-rock aquifers. U.S. Geological Survey 999 Number for areas that are not a principal aquifer. U.S. Geological Survey ROCK_TYPENumber5 AQ_NAME The aquifer unit name. U.S. Geological Survey There is no predefined set of official aquifer names. The names used in this data set are listed below. There should be a direct correlation between the values of the rock_type and rock_name attributes, and between the aq_name and aq_code attributes. The aq_names are as follows: >aq_code -- aq_name >0 -- null value, assigned to null polygon >101 -- Basin and Range 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-Willamette Lowland aquifer system >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 -- Mississippian aquifer of Michigan >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 >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 >602 -- Northern California volcanic-rock aquifers >603 -- Pliocene and younger basaltic-rock aquifers >604 -- Miocene basaltic-rock aquifers >605 -- Volcanic-and sedimentary-rock aquifers >606 -- Snake River Plain aquifer system >607 -- Columbia Plateau aquifer system >999 -- Not a principal aquifer (field left blank). Rocks that are > generally poorly permeable but locally may contain productive > aquifers. AQ_NAMEString65 AQ_CODE The code number relating to the aquifer unit name. There should be a direct correlation between the values of the rock_type and rock_name attributes, and between the aq_name and aq_code attributes. U.S. Geological Survey 0 999 AQ_CODENumber5 Aquifer boundaries and internal contacts (described by aquifrp.aat or aquifrl025.dbf) The limits of the aquifers shown. U.S. Geological Survey Shape The representation of the entity in the data. U.S. Geological Survey Polyline 1-dimensional element that surrounds a 2-dimensional element. ESRI GIS software FNODE# or Fnode_ Internal number of the from-node. U.S. Geological Survey 1 5632 TNODE# or Tnode_ Internal number of the to-node. U.S. Geological Survey 1 5632 5 LPOLY# or Lpoly_ Internal number of the polygon to the left of the arc. U.S. Geological Survey 1 4277 5 RPOLY# or Rpoly_ Internal number of the polygon to the right of the arc. U.S. Geological Survey 1 4267 Length The length of the arc in coverage units. U.S. Geological Survey 0.00159 16.14569 Aquifrp025# or Aquifrp025 Internal feature number. U.S. Geological Survey 1 6802 Aquifrp025-ID (Export format only) User-assigned feature number. U.S. Geological Survey 1 6795 Lntype The line category. U.S. Geological Survey 1 Coastline or international boundary. U.S. Geological Survey 2 Interior aquifer contact line. U.S. Geological Survey U.S. Geological Survey, Water Resources Division Mailing address

12201 Sunrise Valley Drive

Reston VA 20192 USA 1-800-426-9000 Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made by the U.S. Geological Survey regarding the utility of the data on any other system, nor shall the act of distribution constitute any such warranty. ARCE 10.14710.147 http://nationalatlas.gov/atlasftp.html CD-ROM tar ESRI Shapefile 10.14710.147 <http://nationalatlas.gov/atlasftp.html> CD-ROM tar SDTS 10.14710.147 <http://nationalatlas.gov/atlasftp.html> CD-ROM tar There is no charge for the online option. For National Atlas files ordered on CD-ROM there is a base price of $45.00 per disc, a handling fee of $5.00, and a per-file charge based on file size. The charge for files less than 10 megabytes in size is $1.00. The charge for files that range in size from 10 to 150 megabytes is $7.50. The charge for files of 150 megabytes or larger is $15.00. The charge is $7.50 for the Principal Aquifers of the 48 Conterminous United States data set. To order files on CD-ROM, please see http://nationalatlas.gov/atlasftp.html#q12. Downloadable Data 20040205 U.S. Geological Survey Chief, Cartographic and Publications Program, Water Resources Division mailing and physical address

505 Science Drive

Madison WI 53711 USA 608-238-9333 FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 None Unclassified None enlocal timehttp://www.esri.com/metadata/esriprof80.htmlESRI Metadata Profile {566733FA-F05A-4070-A1FA-2E63A1F2F12A}2003062314385100FALSE20040205111344002004020511134400Microsoft Windows 2000 Version 5.1 (Build 2600) Service Pack 1; ESRI ArcCatalog 8.3.0.800aquifrp025-124.755791-66.93956149.38561924.5183221-124.755791-66.93956149.38561924.5183221ISO 19115 Geographic Information - MetadataDIS_ESRI1.0dataset002file://\\KERNCOG02\SYS\GIS\Unprocessed\Chris\Kern_MEAR\Final\Water\aquifrp025.shpLocal Area Network10.147ShapefileGCS_North_American_1983427620040205