# National Hydrography Dataset (NHD)

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## Metadata:

- Identification_Information
- Data_Quality_Information
- Spatial_Data_Organization_Information
- Spatial_Reference_Information
- Entity_and_Attribute_Information
- Distribution_Information
- Metadata_Reference_Information

Identification_Information:
  Citation:
    Citation_Information:
      Originator:
        U.S. Geological Survey in cooperation with U.S. Environmental Protection Agency and other State and local partners (see dataset specific metadata under Data_Set_Credit for details)
      Publication_Date: Unknown
      Title: National Hydrography Dataset (NHD)
      Geospatial_Data_Presentation_Form: map
      Publication_Information:
        Publication_Place: Reston, Virginia
        Publisher: U.S. Geological Survey
      Online_Linkage: <http://nhd.usgs.gov/>
  Description:
    Abstract:
      The National Hydrography Dataset (NHD) is a feature-based database that interconnects and uniquely identifies the stream segments or reaches that make up the nation's surface water drainage system. NHD data was originally developed at 1:100,000 scale and exists at that scale for the whole country. High resolution NHD adds detail to the original 1:100,000-scale NHD. (Data for Alaska, Puerto Rico and the Virgin Islands was developed at high-resolution, not 1:100,000 scale.) Like the 1:100,000-scale NHD, high resolution NHD contains reach codes for networked features and isolated lakes, flow direction, names, stream level, and centerline representations for areal water bodies. Reaches are also defined to represent waterbodies and the approximate shorelines of the Great Lakes, the Atlantic and Pacific Oceans and the Gulf of Mexico. The NHD also incorporates the National Spatial Data Infrastructure framework criteria set out by the Federal Geographic Data Committee.
    Purpose:
      The NHD is a national framework for assigning reach addresses to water-related entities, such as industrial discharges, drinking water supplies, fish habitat areas, wild and scenic rivers. Reach addresses establish the locations of these entities relative to one another within the NHD surface water drainage network much like addresses on streets. Once linked to the NHD by their reach addresses, the upstream/downstream relationships of these water-related entities--and any associated information about them--can be analyzed using software tools ranging from spreadsheets to geographic information systems (GIS). GIS can also be used to combine NHD-based network analysis with other data layers, such as soils, land use and population, to help understand and display their respective effects upon one another. Furthermore, because the NHD provides a nationally consistent framework for addressing and analysis, water-related information linked to reach addresses by one organization (national, state, local) can be shared with other organizations and easily integrated into many different types of applications to the benefit of all. The National Hydrography Dataset is designed to provide comprehensive coverage of hydrologic data for the U.S. For this reason, the NHD initially was based on 1:100,000-scale data, but designed to encourage the development of this higher-resolution data. The development of the high resolution NHD is the culmination of a process that began with the merger of USGS DLG and EPA RF3 to create the NHD. The overall development process was designed as an evolutionary one, so that the qualities of DLG and RF3 would be retained, and the working characteristics of the NHD would be familiar to DLG and RF3 users. This is true now with high resolution NHD which brings the benefits of higher resolution data to the established 1:100,000-scale NHD. The high resolution NHD will improve the integration of water-related data to support the application requirements of a growing national user community and will enable shared maintenance and enhancement. Similarly, high resolution NHD provides richer detail while carrying forward all of the components of the initial 1:100,000 NHD.
  Time_Period_of_Content:
    Time_Period_Information:
      Range_of_Dates/Times:
        Beginning_Date: unknown
        Ending_Date: unknown
    Currentness_Reference: see dataset specific metadata
  Status:
    Progress: In work
    Maintenance_and_Update_Frequency: Irregular
  Spatial_Domain:
    Bounding_Coordinates:
      West_Bounding_Coordinate: -124.7333
      East_Bounding_Coordinate: -067.9500
      North_Bounding_Coordinate: 49.3833
      South_Bounding_Coordinate: 24.5333
  Keywords:
    Theme:
      Theme_Keyword_Thesaurus:
        U.S. Department of the Interior, U.S. Geological Survey, 1999, Standards for National Hydrography Dataset (<http://rockyweb.cr.usgs.gov/nmpstds/nhdstds.html>)
      Theme_Keyword: FWHYDROGRAPHY
      Theme_Keyword: Hydrography
      Theme_Keyword: Stream / River
      Theme_Keyword: Lake / Pond
      Theme_Keyword: Canal / Ditch
      Theme_Keyword: Reservoir
      Theme_Keyword: Spring / Seep
      Theme_Keyword: Swamp / Marsh
      Theme_Keyword: Artificial Path
      Theme_Keyword: Reach
    Place:
      Place_Keyword_Thesaurus:
        U.S. Department of Commerce, 1977, Countries, dependencies, areas of special sovereignty, and their principal administrative divisions (Federal Information Processing Standards 10-3): Washington, D.C., National Institute of Standards and Technology.
      Place_Keyword: US
  Access_Constraints: None
  Use_Constraints:
    None. Acknowledgment of the originating agencies would be appreciated in products derived from these data.
  Point_of_Contact:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: National Hydrography Dataset User Support, USGS
      Contact_Address:
        Address_Type: mailing address
        Address:
          Mail Stop 808 1400 Independence Road
        City: Rolla
        State_or_Province: MO
        Postal_Code: 65401
        Country: USA
      Contact_Voice_Telephone: 573-308-3592
      Contact_Facsimile_Telephone: 573-308-3652
      Contact_Electronic_Mail_Address: nhd@usgs.gov
  Browse_Graphic:
    Browse_Graphic_File_Name:
      <http://mac.usgs.gov/isb/pubs/factsheets/fs10699.graphics/nhd-500.gif>
    Browse_Graphic_File_Description:
      Diagram showing type and character of data provided, 500x352 pixels, 22k bytes.

      In the upper left, the irregular shapes on and around the shaded image of Kentucky are the hydrologic cataloging units that are in the State of Kentucky. On the right is a closer high- level view of three cataloging units, showing their hydrographic features and labeled with the names and numbers of the units. In the oval, a small area is enlarged to show examples of individual features with their reach codes. Note that the reach codes incorporate the eight-digit number of the cataloging unit in which they lie.

    Browse_Graphic_File_Type: GIF
  Data_Set_Credit: See dataset specific metadata

Data_Quality_Information:
  Attribute_Accuracy:
    Attribute_Accuracy_Report:
      The accuracy of the attributes of the source Digital Line Graph data is estimated to be 98.5 percent. One or more of the following methods were used to test attribute accuracy: manual comparison of the source with hardcopy plots; symbolized display of the digital line graph on an interactive computer graphic system; selected attributes that could not be visually verified on plots or on screen were interactively queried and verified on screen. In addition, software validated feature types and characteristics against a master set of types and characteristics, checked that combinations of types and characteristics were valid, and that types and characteristics were valid for the delineation of the feature. Feature types, characteristics, and other attributes conform to the Standards for National Hydrography Dataset - High Resolution (USGS, 1999) as of the date they were loaded into the database. All names on the high-resolution reaches were validated against a current extract from the Geographic Names Information System. The entry and identifier for the names match those in the Geographic Names Information System. The association of each name to reaches has been interactively checked, however, operator error could in some cases apply a name to a wrong reach.
  Logical_Consistency_Report:
    Points, nodes, lines, and areas conform to topological rules. Lines intersect only at nodes, and all nodes anchor the ends of lines. Lines do not overshoot or undershoot other lines where they are supposed to meet. There are no duplicate lines. Lines bound areas and lines identify the areas to the left and right of the lines. Gaps and overlaps among areas do not exist. All areas close.
  Completeness_Report:
    The completeness of the data reflects the content of the sources, which most often are the published USGS topographic quadrangle and/or the U.S. Forest Service Primary Base Series (PBS) map. The USGS topographic quadrangle is usually supplemented by Digital Orthophoto Quadrangles(DOQs). Features found on the ground may have been eliminated or generalized on the source map because of scale and legibility constraints. In general, streams longer than one mile (approximately 1.6 kilometers) were collected. Most streams that flow from a lake were collected regardless of their length. Only definite channels were collected so not all swamp/marsh features have stream/rivers delineated through them. Lake/ponds 100 feet or greater in the shortest axis were collected. Note, however, that these general rules were applied unevenly among maps during compilation. Transport reaches are defined on nearly all features of type stream/river, canal/ditch, artificial path, and connector. Waterbody reaches are defined on all lake/pond features. Detailed capture conditions are provided for every feature type in the Standards for National Hydrography Dataset - High Resolution (USGS, 1999), available online through <http://rockyweb.cr.usgs.gov/nmpstds/nhdstds.html>.
  Positional_Accuracy:
    Horizontal_Positional_Accuracy:
      Horizontal_Positional_Accuracy_Report:
        Statements of horizontal positional accuracy are based on accuracy statements made for U.S. Geological Survey topographic quadrangle maps. These maps were compiled to meet National Map Accuracy Standards. For horizontal accuracy, this standard is met if at least 90 percent of points tested are within 0.02 inch(at map scale) of the true position. Additional offsets to positions may have been introduced where feature density is high to improve the legibility of map symbols. In addition, the digitizing of maps is estimated to contain a horizontal positional error of less than or equal to 0.003 inch standard error(at map scale) in the two component directions relative to the source maps. Visual comparison between the map graphic (including digital scans of the graphic) and plots or digital displays of points, lines, and areas, is used as control to assess the positional accuracy of digital data. Digital map elements along the adjoining edges of data sets are aligned if they are within a 0.02 inch tolerance (at map scale). Features with like dimensionality (for example, features that all are delineated with lines), with or without like characteristics, that are within the tolerance are aligned by moving the features equally to a common point. Features outside the tolerance are not moved; instead, a feature of type connector is added to join the features.
    Vertical_Positional_Accuracy:
      Vertical_Positional_Accuracy_Report:
        Statements of vertical positional accuracy for elevation of water surfaces are based on accuracy statements made for U.S. Geological Survey topographic quadrangle maps. These maps were compiled to meet National Map Accuracy Standards. For vertical accuracy, this standard is met if at least 90 percent of well-defined points tested are within one-half contour interval of the correct value. Elevations of water surface printed on the published map meet this standard; the contour intervals of the maps vary. These elevations were transcribed into the digital data; the accuracy of this transcription was checked by visual comparison between the data and the map.
  Lineage:
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator:
            U.S. Geological Survey in cooperation with U.S. Environmental Protection Agency.
          Publication_Date: 1999
          Title: National Hydrography Dataset (NHD)
      Source_Scale_Denominator: 100000
      Type_of_Source_Media: Online
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 1999
        Source_Currentness_Reference: Publication date
      Source_Citation_Abbreviation: NHD
      Source_Contribution: Reach codes and flow direction attributes.
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: U.S. Geological Survey
          Publication_Date: unknown
          Title: Geographic Names Information System Oracle Database
          Other_Citation_Details: unpublished materials
      Type_of_Source_Media: Online
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 1999
        Source_Currentness_Reference: Custom extract from the GNIS databases
      Source_Citation_Abbreviation: GNIS
      Source_Contribution: Names for reaches and areal water.
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: U.S. Geological Survey
          Publication_Date: unknown
          Title: NHD basic features
          Other_Citation_Details: unpublished materials
      Source_Scale_Denominator: 24000
      Type_of_Source_Media: Online
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: unknown
        Source_Currentness_Reference: Date the revision process step was completed.
      Source_Citation_Abbreviation: NHD basic features
      Source_Contribution: Spatial and attribute information.
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: (see dataset specific metadata)
          Publication_Date: unknown
          Title:
            Subbasin boundaries (formerly called Cataloging Unit Boundaries)
      Type_of_Source_Media: Online
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: unknown
        Source_Currentness_Reference: (see dataset specific metadata)
      Source_Citation_Abbreviation: Subbasin boundaries
      Source_Contribution: Updated Subbasin boundaries
    Process_Step:
      Process_Description:
        Create high-resolution NHD from various sources. Source files were converted to ArcInfo coverages and projected to a common projection (Albers NAD83 meters). Coverages were then panelled into one coverage and arcs within 12 meters of each other along the neatline were snapped together if the feature type were the same. Next, the 10-digit Hydrologic Unit Code (HUC) boundary was obtained. The HUC boundary was projected to the Albers projection and used to extract features from the paneled coverage that fell partially or entirely within the boundary. Next, arcs from the extracted coverage were grouped in order to examine the connectivity of the data set for flow determination. In some cases it was necessary to correct digitizing errors. Using DRGs, available evidence, or cartographic judgement, lines called connectors were added to join features that were deemed to have flow between each other. All arcs were directed downstream and the nodes were prepared to help create artificial paths through 2-D waterbodies and complete the flow through the hydrography network. The artificial path coverage was combined with the single line stream network to create the drainage network. The drainage network was grouped again, and each group was directed downstream. Feature codes (fcodes) were assigned to landmark, network, waterbody features through a crosswalk that converts DLG-3 attributes to fcodes, where an fcode is a five digit integer that encodes a set of feature type characteristics. Reach codes and associated attributes were conflated from the med-res NHD data to the high-res drainage network and 2-D waterbodies. Several checks were performed to validate the reach transfer process. Any reach codes that could not be maintained are tracked in the Reach Cross Reference table. New reaches that do not exist in the mres-res data were defined according to reach delineation rules (See <http://nhd.usgs.gov/chapter1/index.html>). New waterbody reaches were assigned to 2-D lake/pond and reservoir features that do not exist in the med-res NHD. New reaches were assigned reach code values that are sequentially ordered to 2-D and then 1-D reaches. New high-res reach codes are larger than any existing med-res reach code in the associated Catalog Unit. Additional Geographic Names that exist in the Geographic Names Information System (GNIS) were added to reaches in the high-res dataset. Names for the high-res drainage network were interactively transferred from the vector GNIS coverage. Additional GNIS names for point and waterbody features were also added.
      Source_Used_Citation_Abbreviation: NHD basic features
      Source_Used_Citation_Abbreviation: GNIS
      Source_Used_Citation_Abbreviation: Subbasin boundaries
      Source_Used_Citation_Abbreviation: NHD
      Process_Date: unknown
      Source_Produced_Citation_Abbreviation: High-resolution NHD

Spatial_Data_Organization_Information:
  Direct_Spatial_Reference_Method: Vector

Spatial_Reference_Information:
  Horizontal_Coordinate_System_Definition:
    Geographic:
      Latitude_Resolution: 0.0000001
      Longitude_Resolution: 0.0000001
      Geographic_Coordinate_Units: Decimal Degrees
    Geodetic_Model:
      Horizontal_Datum_Name: North American Datum 1983
      Ellipsoid_Name: Geodetic Reference System 80
      Semi-major_Axis: 6378137
      Denominator_of_Flattening_Ratio: 298.257
  Vertical_Coordinate_System_Definition:
    Altitude_System_Definition:
      Altitude_Datum_Name: National Geodetic Vertical Datum of 1929
      Altitude_Resolution: 1.0
      Altitude_Distance_Units: feet
      Altitude_Encoding_Method: attribute values

Entity_and_Attribute_Information:
  Overview_Description:
    Entity_and_Attribute_Overview:
      The National Hydrography Dataset is a comprehensive set of digital spatial data that encodes information about naturally occurring and constructed bodies of water, paths through which water flows, and related entities. The information encoded about features includes classification by type, other characteristics, a unique common identifier, the feature length or area, and (rarely) elevation of the surface of water pools and a description of the stage of the elevation. For reaches, encoded information includes a reach code, the date the reach code was assigned, a unique common identifier, the reach length or area, and, for transport reaches, the stream level. Names and their identifiers in the Geographic Names Information System, are assigned to reaches or, if no reach is available, to features. The data also contain relations among reaches that encode the direction of water flow, metadata, and information that supports the exchange of future updates and improvements to the data.

      The names and definitions of all feature types, characteristics, and values are in U.S. Geological Survey, 1999, Standards for National Hydrography Dataset: Reston, Virginia, U.S. Geological Survey. The document is available online through <http://rockyweb.cr.usgs.gov/nmpstds/nhdstds.html>. Information about tables and fields in the data are available from the user documentation for the National Hydrography Dataset.

    Entity_and_Attribute_Detail_Citation: <http://nhd.usgs.gov/techref.html>

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: Virginia
        Postal_Code: 20192
      Contact_Voice_Telephone: 1-888-ASK-USGS
      Hours_of_Service: 0800-1600
      Contact_Instructions:
        In addition to the address above there are other ESIC offices throughout the country. A full list of these offices is at: URL: <http://ask.usgs.gov/sils_index.html>
  Resource_Description: National Hydrography Dataset (NHD)
  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 USGS 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: Arc/Info export
        Format_Version_Number: 8.x
        Format_Information_Content: Hydrographic features and attributes
        File_Decompression_Technique: tar and uncompress
      Digital_Transfer_Option:
        Online_Option:
          Computer_Contact_Information:
            Network_Address:
              Network_Resource_Name: <http://nhd.usgs.gov/>
    Fees: none

Metadata_Reference_Information:
  Metadata_Date: 20030213
  Metadata_Contact:
    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
      Contact_Voice_Telephone: 1-888-ASK-USGS
      Contact_Electronic_Mail_Address: ask@usgs.gov
  Metadata_Standard_Name: Content Standard for Digital Geospatial Metadata
  Metadata_Standard_Version: FGDC-STD-001-1998

Generated by `mp` version 2.7.33 on Thu Feb 13 12:01:28 2003