Identification_Information:
  Citation:
    Citation_Information:
      Originator: Jim Monical
      Publication_Date: Unpublished Material
      Title: Major Aquifers, Southwestern United States
      Geospatial_Data_Presentation_Form: vector digital data
      Other_Citation_Details: Original data set may be obtained from www.nationalatlas.gov
      Online_Linkage: http://www.nationalatlas.gov
  Description:
    Abstract:
      This data set contains major aquifer boundaries. This data set is a subset of a national data set obtained from the National Atlas of the United States of America (nationalatlas.gov). The metadata for this data set is the original data set metadata; however, it was updated to reflect the changes that occured while creating this subset. This data set was used as part of U.S. Geological Survey Scientific Investigations Report 2006-5315, "Dissolved solids in basin-fill aquifers and streams in the Southwestern United States", by Anning and others (http://water.usgs.gov/nawqa/studies/mrb/salinity.html)


      The original data set contains the shallowest principal aquifers of the conterminous United States, Hawaii, Puerto Rico, and the U.S. Virgin Islands, portrayed as polygons. It 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 the original data set. The original data set is a replacement for the July 1998 data set called Principal Aquifers of the 48 Conterminous United States.
    Purpose: This data set is intended to assist USGS scientists in their studies.
    Supplemental_Information:
      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 These aquifer areas are not necessarily the only areas in which ground water can be withdrawn, for two reasons: 1) The aquifers shown may have a larger areal extent than is represented here.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 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.
  Time_Period_of_Content:
    Time_Period_Information:
      Single_Date/Time:
        Calendar_Date: 200310
    Currentness_Reference: publication date
  Status:
    Progress: Complete
    Maintenance_and_Update_Frequency: None planned
  Spatial_Domain:
    Bounding_Coordinates:
      West_Bounding_Coordinate: -121.969348
      East_Bounding_Coordinate: -104.476747
      North_Bounding_Coordinate: 43.929339
      South_Bounding_Coordinate: 29.772459
  Keywords:
    Theme:
      Theme_Keyword_Thesaurus: none
      Theme_Keyword: ground-water
    Place:
      Place_Keyword: Arizona
      Place_Keyword: California
      Place_Keyword: Colorado
      Place_Keyword: Idaho
      Place_Keyword: Nevada
      Place_Keyword: New Mexico
      Place_Keyword: Oregon
      Place_Keyword: Utah
      Place_Keyword: Wyoming
  Access_Constraints: none
  Use_Constraints: 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.
  Point_of_Contact:
    Contact_Information:
      Contact_Person_Primary:
        Contact_Person: Jim Monical
        Contact_Organization: Jim Monical
      Contact_Position: GIS Specialist
      Contact_Address:
        Address_Type: mailing and physical address
        Address: 520 N. Park Avenue, Suite 221
        City: tucson
        State_or_Province: AZ
        Postal_Code: 85719
      Contact_Voice_Telephone: 520 670-6671 x260
      Contact_Electronic_Mail_Address: jmonical@usgs.gov
  Data_Set_Credit: 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 Discipline, 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.
  Native_Data_Set_Environment: Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.2.2.1350
Data_Quality_Information:
  Logical_Consistency_Report: Polygon and chain-node topology are present. Each polygon is closed and has one label point.
  Lineage:
    Process_Step:
      Process_Description:
        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 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.
      Source_Used_Citation_Abbreviation: e:\eprojects\swsalinity\aquifers
    Process_Step:
      Process_Description: 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 region boundary, depending on a cartographic assessment of the instance.
    Process_Step:
      Process_Description: The Principal Aquifers map published in 1998 was reviewed and modified, resulting in 57 aquifers, 36 of which were the same geographically as in the 1998 publication. Aquifers were aggregated, divided, renamed and updated from more recent publications, using a variety of techniques, which include scanning, importing unpublished digital data and paper compilation at 1:2,500,000 scale. The updated Adobe Illustrator aquifer data was exported into a DXF file. The DXF file was converted to a coverage. Using the TRANSFORM command, the coverage containing the aquifer lines was rubber-sheeted to the coverage containing registration tics, and was then projected from geographic coordinates to Albers Equal-Area Conic projection for verification purposes. The aquifer coverage was cleaned, the topology was built, and labels were added. Attributes were added as necessary.
    Process_Step:
      Process_Description: Original data set clipped to study area boundary.
      Process_Contact:
        Contact_Information:
          Contact_Person_Primary:
            Contact_Person: Jim Monical
            Contact_Organization: U.S. Geological Survey, Arizona Water Science Center
          Contact_Address:
            Address_Type: mailing and physical address
            Address: 520 N. Park Avenue, Suite 221
            City: Tucson
            State_or_Province: Arizona
            Postal_Code: 85719
            Country: USA
          Contact_Voice_Telephone: (520)670-6671
          Contact_Electronic_Mail_Address: jmonical@usgs.gov
    Process_Step:
      Process_Description: Deleted unneeded attributes, Renamed AQ_NAME to MAJ_AQUIFER. Merged MAJ_AQUIFER = "Pacific Northwest basin-fill aquifers" into "Basin and Range basin-fill aquifers"
Spatial_Data_Organization_Information:
  Direct_Spatial_Reference_Method: Vector
  Point_and_Vector_Object_Information:
    SDTS_Terms_Description:
      SDTS_Point_and_Vector_Object_Type: G-polygon
      Point_and_Vector_Object_Count: 813
    SDTS_Terms_Description:
      SDTS_Point_and_Vector_Object_Type: Label point
      Point_and_Vector_Object_Count: 814
    SDTS_Terms_Description:
      SDTS_Point_and_Vector_Object_Type: GT-polygon composed of chains
      Point_and_Vector_Object_Count: 813
    SDTS_Terms_Description:
      SDTS_Point_and_Vector_Object_Type: Point
      Point_and_Vector_Object_Count: 4
Spatial_Reference_Information:
  Horizontal_Coordinate_System_Definition:
    Planar:
      Map_Projection:
        Map_Projection_Name: Albers Conical Equal Area
        Albers_Conical_Equal_Area:
          Standard_Parallel: 29.500000
          Standard_Parallel: 45.500000
          Longitude_of_Central_Meridian: -96.000000
          Latitude_of_Projection_Origin: 23.000000
          False_Easting: 0.000000
          False_Northing: 0.000000
      Planar_Coordinate_Information:
        Planar_Coordinate_Encoding_Method: coordinate pair
        Coordinate_Representation:
          Abscissa_Resolution: 0.004096
          Ordinate_Resolution: 0.004096
        Planar_Distance_Units: meters
    Geodetic_Model:
      Horizontal_Datum_Name: North American Datum of 1983
      Ellipsoid_Name: Geodetic Reference System 80
      Semi-major_Axis: 6378137.000000
      Denominator_of_Flattening_Ratio: 298.257222
  Vertical_Coordinate_System_Definition:
    Altitude_System_Definition:
      Altitude_Resolution: 0.000010
      Altitude_Encoding_Method: Explicit elevation coordinate included with horizontal coordinates
Entity_and_Attribute_Information:
  Detailed_Description:
    Entity_Type:
      Entity_Type_Label: MajAquifers
      Entity_Type_Definition: A subdivision of the Earth, used for the collection and organization of hydrologic data.
      Entity_Type_Definition_Source: U.S. Geological Survey
    Attribute:
      Attribute_Label: AREA
      Attribute_Definition: Area of feature in internal units squared.
      Attribute_Definition_Source: ESRI
      Attribute_Domain_Values:
        Unrepresentable_Domain: Positive real numbers that are automatically generated.
    Attribute:
      Attribute_Label: PERIMETER
      Attribute_Definition: Perimeter of feature in internal units.
      Attribute_Definition_Source: ESRI
      Attribute_Domain_Values:
        Unrepresentable_Domain: Positive real numbers that are automatically generated.
    Attribute:
      Attribute_Label: Shape
      Attribute_Definition: Feature geometry.
      Attribute_Definition_Source: ESRI
      Attribute_Domain_Values:
        Unrepresentable_Domain: Coordinates defining the features.
    Attribute:
      Attribute_Label: MAJ_AQUIFER
      Attribute_Definition: The aquifer unit name.
      Attribute_Definition_Source: U.S. Geological Survey
    Attribute:
      Attribute_Label: SHAPE_AREA
    Attribute:
      Attribute_Label: OBJECTID
      Attribute_Definition: Internal feature number.
      Attribute_Definition_Source: ESRI
      Attribute_Domain_Values:
        Unrepresentable_Domain: Sequential unique whole numbers that are automatically generated.
    Attribute:
      Attribute_Label: SA_MAJAQ_
    Attribute:
      Attribute_Label: SA_MAJAQ_ID
    Attribute:
      Attribute_Label: Shape_Length
      Attribute_Definition: Length of feature in internal units.
      Attribute_Definition_Source: ESRI
      Attribute_Domain_Values:
        Unrepresentable_Domain: Positive real numbers that are automatically generated.
    Attribute:
      Attribute_Label: Shape_Area
      Attribute_Definition: Area of feature in internal units squared.
      Attribute_Definition_Source: ESRI
      Attribute_Domain_Values:
        Unrepresentable_Domain: Positive real numbers that are automatically generated.
Distribution_Information:
  Resource_Description: Original data set may be obtained from www.nationalatlas.gov
  Distribution_Liability: 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.
  Standard_Order_Process:
    Digital_Form:
      Digital_Transfer_Information:
        Transfer_Size: 0.730
Metadata_Reference_Information:
  Metadata_Date: 20071004
  Metadata_Contact:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: U.S. Geological Survey, Arizona Water Science Center
        Contact_Person: Jim Monical
      Contact_Address:
        Address_Type: mailing and physical address
        Address: 520 N. Park Avenue, Suite 221
        City: Tucson
        State_or_Province: Arizona
        Postal_Code: 85719
        Country: USA
      Contact_Voice_Telephone: (520)670-6671
      Contact_Electronic_Mail_Address: jmonical@usgs.gov
  Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
  Metadata_Standard_Version: FGDC-STD-001-1998
  Metadata_Time_Convention: local time
  Metadata_Extensions:
    Online_Linkage: http://www.esri.com/metadata/esriprof80.html
    Profile_Name: ESRI Metadata Profile