Identification_Information:
  Citation:
    Citation_Information:
      Originator: John Watermolen, U.S. Geological Survey
      Publication_Date: 200506
      Title: 1:2,000,000-Scale Hydrologic Unit Boundaries
      Edition: Version 2.4
      Geospatial_Data_Presentation_Form: Map
      Publication_Information:
        Publication_Place: Reston, VA
        Publisher: National Atlas of the United States
      Online_Linkage: 
        <http://nationalatlas.gov/atlasftp.html?openChapters=chpwater#chpwater>
  Description:
    Abstract:
      This map layer contains hydrologic unit boundaries and codes for the 
      United States, Puerto Rico, and the U.S. Virgin Islands.  It was revised 
      for inclusion in the National Atlas of the United States of America, and 
      updated to match the streams file created by the USGS National Mapping 
      Division (NMD) for the National Atlas of the United States of America. 
      This is a revised version of the November 2002 map layer.
    Purpose:
      These data are intended for geographic display and analysis at the 
      national level, and for large regional areas.  The data should be
      displayed and analyzed at scales appropriate for 1:2,000,000-scale data. 
      No responsibility is assumed by the U.S. Geological Survey or the National 
      Atlas of the United States in the use of these data.
    Supplemental_Information:
      Any use of trade, product, or firm names is for descriptive purposes only 
      and does not imply endorsement by the U.S. Government.

      Although this Federal Geographic Data Committee-compliant metadata file is 
      intended to document the map layer in nonproprietary form, as well as in 
      ArcInfo format, this metadata file may include some ArcInfo-specific 
      terminology.

      Hydrologic Unit Code (HUC) areas in this file do not necessarily match 
      those published in Water-Supply Paper 2294 (Seaber et al).  The file has 
      finer resolution than the maps used to determine areas published in the 
      Water-Supply Paper.

      The ArcInfo version of this file contains two additional annotation 
      layers.  One layer is called anno.maplabel1, and contains the first six 
      digits for each accounting unit.  The labels for Accounting Regions 1 
      though 9 have a "0" in front of the number.  The second layer is called
      anno.catnum, and contains the last two digits for each cataloging unit.  
      All numbers were checked manually against a 1:2,000,000-scale plot of the 
      data.
  
  Time_Period_of_Content:
    Time_Period_Information:
      Single_Date/Time:
        Calendar_Date: 200505
    Currentness_Reference: Ground condition

  Status:
    Progress: Complete
    Maintenance_and_Update_Frequency: As needed

  Spatial_Domain:
    Bounding_Coordinates:
      West_Bounding_Coordinate: 170.87
      East_Bounding_Coordinate: -66.88
      North_Bounding_Coordinate: 71.77
      South_Bounding_Coordinate: 17.68

  Keywords:
    Theme:
      Theme_Keyword_Thesaurus: ISO 19115 Topic Category
      Theme_Keyword: Inland waters
    Theme:
      Theme_Keyword_Thesaurus: None
      Theme_Keyword: Hydrologic Unit Boundaries
      Theme_Keyword: Hydrologic Unit Codes
      Theme_Keyword: Drainage Basins
      Theme_Keyword: Cataloging Units
      Theme_Keyword: Hydrologic Units
      Theme_Keyword: Watersheds
    Place:
      Place_Keyword_Thesaurus: None
      Place_Keyword: United States
      Place_Keyword: Alabama      
      Place_Keyword: Alaska
      Place_Keyword: Arizona
      Place_Keyword: Arkansas
      Place_Keyword: California
      Place_Keyword: Colorado
      Place_Keyword: Connecticut
      Place_Keyword: Delaware
      Place_Keyword: District of Columbia
      Place_Keyword: Florida
      Place_Keyword: Georgia    
      Place_Keyword: Hawaii
      Place_Keyword: Idaho
      Place_Keyword: Illinois
      Place_Keyword: Indiana
      Place_Keyword: Iowa
      Place_Keyword: Kansas
      Place_Keyword: Kentucky
      Place_Keyword: Louisiana
      Place_Keyword: Maine
      Place_Keyword: Maryland
      Place_Keyword: Massachusetts
      Place_Keyword: Michigan
      Place_Keyword: Minnesota
      Place_Keyword: Mississippi
      Place_Keyword: Missouri
      Place_Keyword: Montana
      Place_Keyword: Nebraska
      Place_Keyword: Nevada
      Place_Keyword: New Hampshire
      Place_Keyword: New Jersey
      Place_Keyword: New Mexico
      Place_Keyword: New York
      Place_Keyword: North Carolina
      Place_Keyword: North Dakota
      Place_Keyword: Ohio
      Place_Keyword: Oklahoma
      Place_Keyword: Oregon
      Place_Keyword: Pennsylvania
      Place_Keyword: Rhode Island
      Place_Keyword: South Carolina
      Place_Keyword: South Dakota
      Place_Keyword: Tennessee
      Place_Keyword: Texas
      Place_Keyword: Utah
      Place_Keyword: Vermont
      Place_Keyword: Virginia
      Place_Keyword: Washington
      Place_Keyword: West Virginia
      Place_Keyword: Wisconsin
      Place_Keyword: Wyoming      
      Place_Keyword: Puerto Rico
      Place_Keyword: Virgin Islands
      Place_Keyword: U.S. Virgin Islands  

  Access_Constraints: None

  Use_Constraints: 
    None.  Acknowledgment of the National Atlas of the United States of America 
    and (or) the U.S. Geological Survey would be appreciated in products derived 
    from these data.

  Point_of_Contact:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: U.S. Geological Survey
      Contact_Position: CAPP Chief
      Contact_Address:
        Address_Type: Mailing and physical address
        Address: 505 Science Dr.
        City: Madison
        State_or_Province: WI
        Postal_Code: 53711-1061
        Country: USA
      Contact_Voice_Telephone: 608-238-9333
      Contact_Facsimile_Telephone: 608-238-9334
      Contact_Electronic_Mail_Address: atlasmail@usgs.gov

  Data_Set_Credit:
    Others who have helped with this map layer and the metadata include Steve 
    Denowski, Greg Allord, Curtis Price, Ken Lanfear and David Lorenz, in 
    addition to other colleagues within the U.S. Geological Survey.

  Native_Data_Set_Environment: 
    The file is stored in Windows NT 4.0 Intel, ArcInfo version 7.1.1.

  Cross_Reference:
    Citation_Information:
      Originator: U.S. Geological Survey
      Publication_Date: 1974-1987
      Title: State Hydrologic Unit Map (for each State)
      Geospatial_Data_Presentation_Form: Map
      Publication_Information:
        Publication_Place: Reston, VA
        Publisher: U.S. Geological Survey
      Online_Linkage: <http://water.usgs.gov/GIS/huc.html>

Data_Quality_Information:
  Attribute_Accuracy:
    Attribute_Accuracy_Report:
      The arc attributes were manually checked by assigning unique line weights 
      and colors to the values, and then plotting the data.  The plots were then 
      compared to the source.

      The polygon attributes were checked by comparing a 1:2,000,000-scale plot 
      to the source.  The attribute accuracy is estimated at 99%.
  Logical_Consistency_Report:
    Polygon and chain-node topology are present.  All polygons are labeled and 
    were tested by using the ArcInfo command labelerrors.  All polygons were 
    checked for closure and intersections by using the ArcInfo intersecterr 
    command.  The file is clean.
  Completeness_Report:
    This file contains hydrologic unit boundaries and codes for all 50 States, 
    Puerto Rico, and the U.S. Virgin Islands.  Boundaries and codes are included 
    for regions, subregions, accounting units, and cataloging units.
  Positional_Accuracy:
    Horizontal_Positional_Accuracy:
      Horizontal_Positional_Accuracy_Report:
        The accuracy of the original map layer was checked by comparing the 
        digital files to several data sources.  First, both the line work and 
        the polygon labels were checked against the source compilation.  No 
        digitization errors were found during this phase.

        Next, the hydrologic unit boundaries were compared to the 1970 
        1:2,000,000-scale DLG stream file and the 1:500,000-scale Hydrologic 
        Unit Maps.  Plots containing both the streams and the hydrologic unit 
        boundaries were made at a scale of 1:2,000,000.  Hydrologic unit 
        boundary intersections were checked, as well as problem areas such as 
        points where streams crossed hydrologic unit boundaries on the plot but 
        not on the hydrologic unit map.  More than 400 errors were found.  All 
        errors that could be corrected were corrected.  The remaining errors
        could not be corrected because the streams were in error rather than the 
        hydrologic unit boundaries. 

        Finally, the hydrologic unit boundaries were plotted at 1:2,000,000 
        scale and compared to the NMD 1998 1:2,000,000-scale hydrologic data 
        set.  Any discrepancies were addressed by reference to either the 
        1:500,000-scale or the 1:100,000-scale maps.  The exceptions to this 
        were the hydrologic unit boundaries for Alaska, Hawaii, Puerto Rico, and 
        the U.S. Virgin Islands.  The Alaska boundaries were checked on a 
        1:2,500,000-scale plot but not modified, because the boundaries cross 
        glaciers, and it is difficult to distinguish flow from the glaciers.
        The Hawaii hydrologic unit boundaries were not reviewed because each 
        island represents a cataloging unit.  The Puerto Rico and U.S. Virgin 
        Islands boundaries were not plotted but were reviewed on-screen using a 
        1:1,000,000 hydrologic map layer created for the 1991 National Water
        Summary.

        The horizontal positional accuracy of the data matches the positional 
        accuracy of the original compilation.
  Lineage:
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: U.S. Geological Survey
          Publication_Date: 1974-1987
          Title: State Hydrologic Unit Maps (for each State)
          Geospatial_Data_Presentation_Form: Map
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: 
              U.S. Geological Survey, Office of Water Data Coordination
          Online_Linkage: <http://water.usgs.gov/GIS/huc.html>
      Source_Scale_Denominator: 500,000
      Type_of_Source_Media: Mylar separate
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Range_of_Dates/Times:
            Beginning_Date: 1974
            Ending_Date: 1987
        Source_Currentness_Reference: Publication date
      Source_Citation_Abbreviation: HUCmaps
      Source_Contribution: Linework for the map layer.

    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: Seaber, Paul R.
          Originator: Kapinos, F. Paul
          Originator: Knapp, George L.
          Publication_Date: 1987
          Title: Hydrologic Unit Maps 
          Series_Information:
            Series_Name: Water-Supply Paper
            Issue_Identification: 2294
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: U.S. Geological Survey
          Online_Linkage: <http://water.usgs.gov/GIS/huc.html>
      Type_of_Source_Media: Paper map
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 1987
        Source_Currentness_Reference: Publication date
      Source_Citation_Abbreviation: Seaber
      Source_Contribution: Cataloging unit names for all States except Alaska.

    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: U.S. Geological Survey
          Publication_Date: 1987
          Title: Alaska State Hydrologic Unit Map
          Geospatial_Data_Presentation_Form: Map
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: U.S. Geological Survey
          Online_Linkage: <http://water.usgs.gov/GIS/huc.html>
      Source_Scale_Denominator: 2,500,000
      Type_of_Source_Media: Mylar separate
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 1987
        Source_Currentness_Reference: Publication date
      Source_Citation_Abbreviation: HUCAKmap
      Source_Contribution: 
        The source contributed line work and names for hydrologic units in 
        Alaska.

    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: U.S. Geological Survey
          Publication_Date: 1972-1980
          Title: 1:2,000,000 DLG Hydrography
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: U.S. Geological Survey
      Source_Scale_Denominator: 2,000,000
      Type_of_Source_Media: Digital file
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Range_of_Dates/Times:
            Beginning_Date: 1972
            Ending_Date: 1980
        Source_Currentness_Reference: Publication date
      Source_Citation_Abbreviation: DLGHY
      Source_Contribution: Location of streams for accuracy testing.
   
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: U.S. Geological Survey
          Publication_Date: 1986
          Title: Hydrologic Unit Codes map
          Edition: Version 1.0
          Geospatial_Data_Presentation_Form: Map
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: U.S. Geological Survey
      Source_Scale_Denominator: 2,000,000
      Type_of_Source_Media: Digital file
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 1986
        Source_Currentness_Reference: Publication date
      Source_Citation_Abbreviation: HUCS10
      Source_Contribution: Intermediate digital file.

    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: U.S. Geological Survey
          Publication_Date: 1992
          Title: Hydrologic Unit Codes map
          Edition: Version 1.1
          Geospatial_Data_Presentation_Form: Map
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: U.S. Geological Survey
      Source_Scale_Denominator: 2,000,000
      Type_of_Source_Media: Digital file
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 1992
        Source_Currentness_Reference: Publication date
      Source_Citation_Abbreviation: HUCS11 
      Source_Contribution: Intermediate digital file.

    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: U.S. Geological Survey
          Publication_Date: 1994
          Title: Hydrologic Unit Codes map
          Edition: Version 1.1.1
          Geospatial_Data_Presentation_Form: Map
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: U.S. Geological Survey
      Source_Scale_Denominator: 2,000,000
      Type_of_Source_Media: Digital file
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 1994
        Source_Currentness_Reference: Publication date
      Source_Citation_Abbreviation: HUCS111
      Source_Contribution: Intermediate digital file.

    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: U.S. Geological Survey
          Publication_Date: 1989
          Title: 1:2,000,000 County Boundaries
          Geospatial_Data_Presentation_Form: Map
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: U.S. Geological Survey
      Source_Scale_Denominator: 2,000,000
      Type_of_Source_Media: Digital file
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 1989
        Source_Currentness_Reference: Publication date
      Source_Citation_Abbreviation: DLGCO
      Source_Contribution: 
        Determination of boundaries for identification of offshore and onshore 
        areas.

    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: U.S. Environmental Protection Agency
          Publication_Date: 1975
          Title: Reach File Version 1.0 Alpha
          Geospatial_Data_Presentation_Form: Map
          Publication_Information:
            Publication_Place: Washington, DC
            Publisher: U.S. Environmental Protection Agency
      Type_of_Source_Media: Digital file
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 1975
        Source_Currentness_Reference: Publication date
      Source_Citation_Abbreviation: RF1
      Source_Contribution: Information on flow between cataloging units.

    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: U.S. Geological Survey
          Publication_Date: 1998
          Title: State Boundaries of the United States
          Geospatial_Data_Presentation_Form: Map
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: U.S. Geological Survey
      Source_Scale_Denominator: 2,000,000
      Type_of_Source_Media: Digital file
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Range_of_Dates/Times:
            Beginning_Date: 1972
            Ending_Date: 1998
        Source_Currentness_Reference: Ground condition
      Source_Citation_Abbreviation: NAStates
      Source_Contribution: Coastline information

    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: U.S. Geological Survey
          Publication_Date: 1998
          Title: Hydrography Features of the United States (linear)
          Geospatial_Data_Presentation_Form: Map
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: U.S. Geological Survey
      Source_Scale_Denominator: 2,000,000
      Type_of_Source_Media: Digital file
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Range_of_Dates/Times:
            Beginning_Date: 1985
            Ending_Date: 1998
        Source_Currentness_Reference: Ground condition
      Source_Citation_Abbreviation: NAHydro
      Source_Contribution: Coastline information

    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: U.S. Geological Survey
          Publication_Date: 19990401
          Title: 1:2,000,000-Scale Hydrologic Unit Boundaries
          Edition: Version 2.0
          Geospatial_Data_Presentation_Form: Map
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: U.S. Geological Survey
      Source_Scale_Denominator: 2,000,000
      Type_of_Source_Media: Digital file
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 19981001
        Source_Currentness_Reference: Ground condition
      Source_Citation_Abbreviation: HUCS20
      Source_Contribution: Spatial and attribute information.

    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: U.S. Geological Survey
          Publication_Date: 200104
          Title: 1:2,000,000-Scale Hydrologic Unit Boundaries
          Edition: Version 2.1
          Geospatial_Data_Presentation_Form: Map
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: U.S. Geological Survey
      Source_Scale_Denominator: 2,000,000
      Type_of_Source_Media: Digital file
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 19981001
        Source_Currentness_Reference: Ground condition
      Source_Citation_Abbreviation: HUCS21
      Source_Contribution: Spatial and attribute information.

    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: U.S. Geological Survey
          Publication_Date: 200201
          Title: 1:2,000,000-Scale Hydrologic Unit Boundaries
          Edition: Version 2.2
          Geospatial_Data_Presentation_Form: Map
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: U.S. Geological Survey
      Source_Scale_Denominator: 2,000,000
      Type_of_Source_Media: Digital file
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 19981001
        Source_Currentness_Reference: Ground condition
      Source_Citation_Abbreviation: HUCS22
      Source_Contribution: Spatial and attribute information.

    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: U.S. Geological Survey
          Publication_Date: 200211
          Title: 1:2,000,000-Scale Hydrologic Unit Boundaries
          Edition: Version 2.3
          Geospatial_Data_Presentation_Form: Map
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: U.S. Geological Survey
      Source_Scale_Denominator: 2,000,000
      Type_of_Source_Media: Digital file
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 19981001
        Source_Currentness_Reference: Ground condition
      Source_Citation_Abbreviation: HUCS23
      Source_Contribution: Spatial and attribute information.

    Process_Step:
      Process_Description:
        The original hydrologic unit boundaries file (HUCS10) was created 
        through the following steps:
        >a) 1:2,000,000-scale stable-base map plots of drainage (streams) and 
        >the latitude/longitude grid were obtained from the USGS National 
        >Mapping Division (NMD).  These plots were in the Lambert Conformal 
        >Conic projection, and used 1:500,000-scale State base map projection 
        >parameters.  Fifteen sections were plotted using 1970 National Atlas 
        >1:2,000,000-scale sectional boundaries.
        >
        >b) Individual State 1:500,000-scale hydrologic unit maps in the Lambert 
        >Conformal Conic projection were photoreduced to 1:2,000,000.
        >
        >c) Hydrologic unit boundaries were compiled and the edges were matched 
        >on scale-stable 1:2,000,000 plots.  The boundaries were combined with 
        >the streams plots for digitizing.
        >
        >d) The hydrologic unit boundaries were digitized by Automated Datatron, 
        >Hyattsville, MD, which digitizes materials on contract for NMD.
        >
        >e) Digital data from Automated Datatron was converted to an ArcInfo 
        >coverage, then checked and corrected.
        >
        >f) A detailed, annotated list was compiled, listing locations where 
        >hydrologic unit boundaries and streams were coincident, or where 
        >1:2,000,000-scale DLG streams were in error.  Wherever possible, 
        >conflicts and errors were resolved.
      Source_Used_Citation_Abbreviation: HUCmaps
      Source_Used_Citation_Abbreviation: DLGHY
      Process_Date: 1985-1992
      Source_Produced_Citation_Abbreviation: HUCS10
    Process_Step:
      Process_Description:
        HUCS11 was created by modifying and correcting the HUCS10 file in 
        ArcInfo, and combining it with a 1:2,000,000-scale U.S. counties file 
        to identify onshore and offshore areas.  Other county attributes were
        excluded.  This process was done in ArcInfo, and used a fuzzy tolerance 
        of 2 meters.  A small part of the original map, which laid on top of 
        part of the Canadian Great Lakes, was deleted.  The attributes were 
        renamed and expanded.
      Source_Used_Citation_Abbreviation: HUCS10
      Source_Used_Citation_Abbreviation: DLGCO
      Process_Date: 1992
      Source_Produced_Citation_Abbreviation: HUCS11
    Process_Step:
      Process_Description:
        A HUCs_2M.TRACE file was created from the River Reach 1 (rf1) coverage, 
        which includes a pointer to the next downstream segment of each reach.  
        The resulting file was added to INFO, along with an index created using 
        the INDEX_HUC.AML.  These files are included in HUCS111 only and are not 
        in the distributed version of the Hydrologic Unit Boundaries map layer.
      Source_Used_Citation_Abbreviation: HUCS11
      Source_Used_Citation_Abbreviation: RF1
      Process_Date: 1994
      Source_Produced_Citation_Abbreviation: HUCS111
    Process_Step:
      Process_Description:
        Using ArcInfo, HUCS111 was compared with the most recent 1:2,000,000-
        scale streams file created by the USGS National Mapping Division (NMD) 
        for inclusion in the National Atlas of the United States of America.  
        Where a stream crossed a hydrologic unit boundary, the boundary was 
        compared to the 1:500,000-scale State hydrologic unit map (Seaber).  If 
        a stream and hydrologic unit boundary intersection could not be resolved 
        by this comparison, the USGS 1:100,000-scale topographic quadrangles 
        were used.  All corrected hydrologic unit boundaries were given a value 
        of 5 for the Error_type attribute.  The boundaries were changed by 
        moving vertices to include the stream in the appropriate hydrologic 
        unit.  All editing was done on-screen.  This step happened May 22, 1998 
        and November 10, 1998.  

        The Region, Subregion, Accounting unit, and Cataloging unit names from 
        Seaber were added to the map layer and spot-checked.  Cataloging unit 
        names for Alaska were added from the Alaska Hydrologic Unit Map
        (HUCAKmap).

        Values for BNDTYPE were determined from the bounding polygons using 
        INDEX_HUC.AML.  The attributes Error_type, Reg_name, Map_label,
        Cat_Name, and Cat_num were added to the file.

        Two annotation layers were also added to the coverage.  One layer is 
        called anno.maplabel1, which shows the first six digits for each 
        accounting unit.  The labels for accounting Regions 1 though 9 have the 
        "0" in front of the number.  The second annotation layer is anno.catnum,
        and this layer has the last 2 digit codes for each cataloging unit.  All 
        numbers were checked manually on a 1:2,000,000-scale plot of the data 
        set.  The cataloging unit names were spot-checked.  The file was 
        modified to agree with the official National Atlas coastline (NAStates)

        The ArcInfo coverage was exported to create the shapefiles and SDTS 
        files.
      Source_Used_Citation_Abbreviation: HUCS111
      Source_Used_Citation_Abbreviation: Seaber
      Source_Used_Citation_Abbreviation: HUCAKmap
      Source_Used_Citation_Abbreviation: NAStates
      Source_Used_Citation_Abbreviation: NAHydro
      Process_Date: 1998
      Source_Produced_Citation_Abbreviation: HUCS20

    Process_Step:
      Process_Description:
        The HUCS20 file was modified and corrected in ArcInfo.  Two Hydrologic 
        unit codes were corrected.  The first error was in western Illinois, 
        Region 07, Subregion 08, Accounting unit 01, where cataloging unit 04 
        was incorrectly tagged 07.  The second error was in northeastern
        Missouri, Region 07, Subregion 11, Accounting unit 00, Cataloging unit 
        01, where the subregion was incorrectly tagged 10.
        
        Misspelled names in sub_name, acc_name, and cat_name were corrected.
        The file was exported to create new shapefiles and SDTS files.
      Source_Used_Citation_Abbreviation: HUCS20
      Process_Date: 2001
      Source_Produced_Citation_Abbreviation: HUCS21

    Process_Step:
      Process_Description:
        The HUCS21 file was modified and corrected in ArcGIS.  One Hydrologic 
        Unit code was corrected in Oregon.  Region 17, Subregion 07, Accounting 
        unit 03, Cataloging unit 01 had all user-defined attribute items 
        incorrectly valued as Region 17, Subregion 09, Accounting unit 00, 
        Cataloging unit 05.
      Source_Used_Citation_Abbreviation: HUCS21
      Process_Date: 200201
      Source_Produced_Citation_Abbreviation: HUCS22

    Process_Step:
      Process_Description:
        The HUCS22 file was modified and corrected in ArcGIS.  One cataloging 
        unit name was corrected in Oregon.  Region 17, Subregion 10, Accounting 
        unit 02, Cataloging unit 03 had the attribute CAT_NAME incorrectly 
        valued as Wilson-Trusk-Nestuccu, Oregon. It was corrected to 
        Wilson-Trask-Nestucca, Oregon.
      Source_Used_Citation_Abbreviation: HUCS22
      Process_Date: 200211
      Source_Produced_Citation_Abbreviation: HUCS23


    Process_Step:
      Process_Description:
        The HUCS23 file was modified and corrected in ArcGIS.  Cataloging unit 
        03050201 had the attribute CAT_NAME incorrectly valued as Copper, South 
        Carolina.  It was corrected to Cooper, South Carolina.  HUC 1103 
        Sub_name was incorrectly valued as Middel Arkansas.  It was corrected to 
        Middle Arkansas.  The codes and all attributes in the following basins 
        were corrected: Cataloging unit 9030006 corrected from 9030004, 
        Cataloging unit 12100204 corrected from 12100303, and Cataloging unit 
        17060206 corrected from 17060203.
      Source_Used_Citation_Abbreviation: HUCS23
      Process_Date: 200505

Spatial_Data_Organization_Information:
  Direct_Spatial_Reference_Method: Vector
  Point_and_Vector_Object_Information:
    SDTS_Terms_Description:
      SDTS_Point_and_Vector_Object_Type: Area point
      Point_and_Vector_Object_Count: 5348
    SDTS_Terms_Description:
      SDTS_Point_and_Vector_Object_Type: Complete chain
      Point_and_Vector_Object_Count: 11576
    SDTS_Terms_Description:
      SDTS_Point_and_Vector_Object_Type: GT-polygon composed of chains
      Point_and_Vector_Object_Count: 5348

Spatial_Reference_Information:
  Horizontal_Coordinate_System_Definition:
    Geographic:
      Latitude_Resolution: 0.0000716142749
      Longitude_Resolution: 0.0000716142749
      Geographic_Coordinate_Units: Decimal degrees
    Geodetic_Model:
      Horizontal_Datum_Name: North American Datum of 1983
      Ellipsoid_Name: GRS1980
      Semi-major_Axis: 6378137.0
      Denominator_of_Flattening_Ratio: 298.257222

Entity_and_Attribute_Information:
  Detailed_Description:
    Entity_Type:
      Entity_Type_Label: 
        Hydrologic Unit (described by HUCS00P020.PAT or Hucs00p020.dbf)
      Entity_Type_Definition: 
        A subdivision of the Earth, used for the collection and organization of 
        hydrologic data.  Regions, subregions, accounting units, and cataloging
        units are all types of hydrologic units.
      Entity_Type_Definition_Source: National Atlas of the United States
    Attribute:
      Attribute_Label: Shape
      Attribute_Definition: The representation of the entity in the data.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: Polygon
          Enumerated_Domain_Value_Definition: 2-dimensional element
          Enumerated_Domain_Value_Definition_Source: ESRI GIS software
    Attribute:
      Attribute_Label: Area
      Attribute_Definition: 
        The size of the shape in coverage units.  In the distributed 
        file, coverage units represent square decimal degrees.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 0.000
          Range_Domain_Maximum: 9.069
    Attribute:
      Attribute_Label: Perimeter
      Attribute_Definition: 
        The perimeter of the shape in coverage units.  In the distributed file, 
        coverage units represent decimal degrees.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
       Range_Domain:
          Range_Domain_Minimum: 0.004
          Range_Domain_Maximum: 41.175
    Attribute:
      Attribute_Label: HUCS00M020# or Hucs00m020
      Attribute_Definition: Internal feature number.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 2
          Range_Domain_Maximum: 5348
    Attribute:
      Attribute_Label: HUCS00M020-ID (Included in Export format file only.)
      Attribute_Definition: User-assigned feature number.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 1
          Range_Domain_Maximum: 5345
    Attribute:
      Attribute_Label: Plytype
      Attribute_Definition: 
        A code indicating the classification of offshore polygons.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: 0
          Enumerated_Domain_Value_Definition: Land, including islands.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: 2
          Enumerated_Domain_Value_Definition: Open water.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
    Attribute:
      Attribute_Label: Huc
      Attribute_Definition: 
        The Hydrologic Unit Code.  The code is 8 digits and can be subdivided as 
        follows:
        >Digits   Type
        >1-2      Water Resource Region
        >1-4      Subregion
        >1-6      Accounting Unit
        >1-8      Cataloging Unit
        >
        This is the same as Cat.  There are six polygons in the file with a Huc 
        of 0; these polygons are not assigned to any hydrologic unit.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 1010001
          Range_Domain_Maximum: 21020002
    Attribute:
      Attribute_Label: Reg_name
      Attribute_Definition: The Water Resource Region name.  
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Codeset_Domain:
          Codeset_Name: 
            Hydrologic Unit Maps: Seaber, P.R., Kapinos, F.P., and Knapp, G.L.: 
            U.S. Geological Survey Water-supply Paper 2294; 1987
          Codeset_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Codeset_Domain:
          Codeset_Name: 
            Alaska State Hydrologic Unit Map, U.S. Geological Survey map; 1987
          Codeset_Source: U.S. Geological Survey
    Attribute:
      Attribute_Label: Map_label
      Attribute_Definition: 
        A 6-digit character string of the hydrologic unit code. This was created 
        to help map production and a zero was added in front of the single digit 
        regions.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 010100
          Range_Domain_Maximum: 210200
    Attribute:
      Attribute_Label: Sub_name
      Attribute_Definition: The Subregion name.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Codeset_Domain:
          Codeset_Name: 
            Hydrologic Unit Maps: Seaber, P.R., Kapinos, F.P., and Knapp, G.L.: 
            U.S. Geological Survey Water-supply Paper 2294; 1987
          Codeset_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Codeset_Domain:
          Codeset_Name: 
            Alaska State Hydrologic Unit Map, U.S. Geological Survey map; 1987
          Codeset_Source: U.S. Geological Survey 
    Attribute:
      Attribute_Label: Acc_name
      Attribute_Definition: The Accounting Unit name.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Codeset_Domain:
          Codeset_Name: 
            Hydrologic Unit Maps: Seaber, P.R., Kapinos, F.P., and Knapp, G.L.: 
            U.S. Geological Survey Water-supply Paper 2294; 1987
          Codeset_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Codeset_Domain:
          Codeset_Name: 
            Alaska State Hydrologic Unit Map, U.S. Geological Survey map; 1987
          Codeset_Source: U.S. Geological Survey 
    Attribute:
      Attribute_Label: Cat_name
      Attribute_Definition: 
        The Cataloging Unit name.  Except in Alaska, this includes the State(s) 
        in which the unit is located. The State name is spelled out except where 
        the cataloging unit name is very long and the cataloging unit is located 
        in several States, in which case the State names are abbreviated with 
        the 2-letter State FIPS code.  Occasionally, State names are truncated 
        rather than abbreviated.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Codeset_Domain:
          Codeset_Name: 
            Hydrologic Unit Maps: Seaber, P.R., Kapinos, F.P., and Knapp, G.L.: 
            U.S. Geological Survey Water-supply Paper 2294; 1987
          Codeset_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Codeset_Domain:
          Codeset_Name: 
            Alaska State Hydrologic Unit Map, U.S. Geological Survey map; 1987
          Codeset_Source: U.S. Geological Survey 
    Attribute:
      Attribute_Label: Huc2
      Attribute_Definition: 
        The number of the Water Resource Region.  This is also the first two
        digits of the Hydrologic Unit Code and is the same as Reg.  A region is
        one of 21 major geographic areas within the U.S. or Caribbean area which 
        contains either the drainage area of a major river or the combined 
        drainage area of a series of rivers.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 1
          Range_Domain_Maximum: 21
    Attribute:
      Attribute_Label: Huc4
      Attribute_Definition: 
        The number of the Subregion.  This is also the first four digits of the 
        Hydrologic Unit Code and is the same as Sub. A subregion is a 
        subdivision of a region and includes the area drained by a river system, 
        a reach of a river and its tributaries in that reach, a closed basin, or 
        a group of streams forming a coastal drainage area.  There are 222 
        subregions.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 101
          Range_Domain_Maximum: 2102
    Attribute:
      Attribute_Label: Huc6
      Attribute_Definition: 
        The number of the Accounting Unit.  This is also the first six digits of 
        the Hydrologic Unit Code and is the same as Act.  The accounting units 
        nest within or are equivalent to the subregions.  There are 352 
        accounting units.  If the last two digits of this number are 00, the 
        accounting unit and subregion are the same.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 10100
          Range_Domain_Maximum: 210200
    Attribute:
      Attribute_Label: Reg
      Attribute_Definition: 
        The number of the Water Resource Region.  This is also the first two 
        digits of the Hydrologic Unit Code, and is the same as Huc2.  A region
        is one of 21 major geographic areas within the U.S. or Caribbean area 
        which contains either the drainage area of a major river or the combined 
        drainage area of a series of rivers.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 1
          Range_Domain_Maximum: 21
    Attribute:
      Attribute_Label: Sub
      Attribute_Definition: 
        The number of the Subregion.  This is also the first four digits of the 
        Hydrologic Unit Code and is the same as Huc4.  A subregion is a 
        subdivision of a region and includes the area drained by a river system,
        a reach of a river and its tributaries in that reach, a closed basin, or 
        a group of streams forming a coastal drainage area.  There are 222 
        subregions.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 101
          Range_Domain_Maximum: 2102
    Attribute:
      Attribute_Label: Acc
      Attribute_Definition: 
        The number of the Accounting Unit.  This is also the first six digits of 
        the Hydrologic Unit Code and is the same as Huc6.  The accounting units 
        nest within or are equivalent to the subregions.  There are 352 
        accounting units.  If the last two digits of this number are 00, the 
        accounting unit and subregion are the same.
      Attribute_Definition_Source: National Atlas of the United States 
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 10100
          Range_Domain_Maximum: 210200
    Attribute:
      Attribute_Label: Cat
      Attribute_Definition:
        The number of the Cataloging Unit.  This is the same as Huc.  A 
        cataloging unit is currently the smallest element in the hierarchy of 
        hydrologic units, and represents part or all of a surface drainage
        basin, a combination of drainage basins, or a distinct hydrologic 
        feature.  There are 2,264 cataloging units.  If the last two digits of 
        this number are 00, the cataloging unit and accounting unit are the 
        same.  Cataloging units may also be referred to as watersheds.  There 
        are 6 polygons in the file with a Cat of 0; these polygons are not 
        assigned to any hydrologic unit.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 1010001
          Range_Domain_Maximum: 21020002
    Attribute:
      Attribute_Label: Cat_num
      Attribute_Definition: 
        The number of the Cataloging Unit.  This is a redefined Huc or Cat 
        number changed into a character string. 
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 1010001
          Range_Domain_Maximum: 21020002
  Detailed_Description:
    Entity_Type:
      Entity_Type_Label: 
        Hydrologic Unit Boundary (described by HUCS00L020.AAT or Hucs00l020.dbf)
      Entity_Type_Definition: A boundary between hydrologic units.
      Entity_Type_Definition_Source: National Atlas of the United States
    Attribute:
      Attribute_Label: Shape
      Attribute_Definition: The representation of the entity in the data.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: Polyline
          Enumerated_Domain_Value_Definition: 
            1-dimensional element that surrounds a 2-dimensional element.
          Enumerated_Domain_Value_Definition_Source: ESRI GIS software
    Attribute:
      Attribute_Label: Fnode# or Fnode_
      Attribute_Definition: Internal sequence number of the from-node.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 1
          Range_Domain_Maximum: 9039
    Attribute:
      Attribute_Label: Tnode# or Tnode_
      Attribute_Definition: Internal sequence number of the to-node.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 1
          Range_Domain_Maximum: 9039
    Attribute:
      Attribute_Label: Lpoly# or Lpoly_
      Attribute_Definition: Internal sequence number of the left polygon.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 1
          Range_Domain_Maximum: 5348
    Attribute:
      Attribute_Label: Rpoly# or Rpoly_
      Attribute_Definition: Internal sequence number of the right polygon.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 1
          Range_Domain_Maximum: 5347
    Attribute:
      Attribute_Label: Length
      Attribute_Definition: 
        The length of the line in coverage units.  In the distributed file, 
        coverage units represent decimal degrees.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 0.000
          Range_Domain_Maximum: 6.143
    Attribute:
      Attribute_Label: US_HUCS_ALB# or Hucs00m020
      Attribute_Definition: Internal feature number.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 1
          Range_Domain_Maximum: 11576
    Attribute:
      Attribute_Label: US_HUCS_ALB-ID (Included in Export format file only.)
      Attribute_Definition: User-assigned feature number.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 1
          Range_Domain_Maximum: 11576
    Attribute:
      Attribute_Label: Bndtype
      Attribute_Definition: 
        The code number describing the location or type of the hydrologic unit 
        boundary.  Boundaries occur between hydrologic units and between onshore 
        and offshore parts of the same hydrologic unit.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: 0
          Enumerated_Domain_Value_Definition: 
            Coastline or International Boundary separating offshore and onshore 
            parts of the same hydrologic unit.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: 2
          Enumerated_Domain_Value_Definition: 
            Land and occasionally water boundary between two Water Resource 
            Regions.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: 4
          Enumerated_Domain_Value_Definition: 
            Land and occasionally water boundary between two Subregions.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: 6
          Enumerated_Domain_Value_Definition: 
            Land and occasionally water boundary between two Accounting Units.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: 8
          Enumerated_Domain_Value_Definition: 
            Land and occasionally water boundary between two Cataloging Units.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
    Attribute:
      Attribute_Label: Error_type
      Attribute_Definition: 
        A code indicating the type of conflict between the streams file and the 
        hydrologic unit boundary.
      Attribute_Definition_Source: National Atlas of the United States
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: 0
          Enumerated_Domain_Value_Definition: No conflict exists.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: 4
          Enumerated_Domain_Value_Definition: 
            There was an error in the streams file.  The hydrologic unit 
            Boundary was not changed.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: 5
          Enumerated_Domain_Value_Definition: 
            There was a conflict between the NMD streams data and the
            1:500,000-scale Hydrologic Unit Boundaries map.  The hydrologic unit 
            boundary was changed to agree with the streams.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
    
Distribution_Information:
  Distributor:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: 
          Earth Science Information Center, U.S. Geological Survey
      Contact_Address:
        Address_Type: Mailing address
        Address: 507 National Center
        City: Reston
        State_or_Province: VA
        Postal_Code: 20192
        Country: USA
      Contact_Voice_Telephone: 1-888-ASK-USGS (1-888-275-8747)
      Contact_Voice_Telephone: 703-648-5920
      Contact_Instructions: 
        In addition to the address above there are other ESIC offices throughout 
        the country.  A full list of these offices is at
        <http://ask.usgs.gov/esic_index.html>.
  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:
        Format_Name: ARCE
      Digital_Transfer_Option:
        Online_Option:
          Computer_Contact_Information:
            Network_Address:
              Network_Resource_Name: 
                <http://nationalatlas.gov/atlasftp.html?openChapters=chpwater#chpwater>
    Digital_Form:
      Digital_Transfer_Information:
        Format_Name: ESRI Shapefile
      Digital_Transfer_Option:
        Online_Option:
          Computer_Contact_Information:
            Network_Address:
              Network_Resource_Name: 
                <http://nationalatlas.gov/atlasftp.html?openChapters=chpwater#chpwater>
    Digital_Form:
      Digital_Transfer_Information:
        Format_Name: SDTS
      Digital_Transfer_Option:
        Online_Option:
          Computer_Contact_Information:
            Network_Address:
              Network_Resource_Name:
                <http://nationalatlas.gov/atlasftp.html?openChapters=chpwater#chpwater>
    Fees:
      There is no charge for the map layer.

Metadata_Reference_Information:
  Metadata_Date: 20060324
  Metadata_Contact:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: U.S. Geological Survey
      Contact_Position: CAPP Chief
      Contact_Address:
        Address_Type: Mailing and physical address
        Address: 505 Science Dr.
        City: Madison
        State_or_Province: WI
        Postal_Code: 53711-1061
        Country: USA
      Contact_Voice_Telephone: 608-238-9333
      Contact_Facsimile_Telephone: 608-238-9334
      Contact_Electronic_Mail_Address: atlasmail@usgs.gov
  Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
  Metadata_Standard_Version: FGDC-STD-001-1998
  Metadata_Security_Information:
    Metadata_Security_Classification_System: None
    Metadata_Security_Classification: Unclassified
    Metadata_Security_Handling_Description: None

