Hydrologic Unit Boundaries: Map Layer Description File

This data was compiled by the U.S. Geological Survey and depicts a hydrologic system that divides and subdivides the United States into successively smaller river basin units. These subdivisions, or hydrologic units, are used for collection and organization of hydrologic data. The hydrologic units outlined in this data represent natural and manmade stream-drainage areas. The boundaries and associated hydrologic unit codes were modified from the State Hydrologic Unit Maps (1:500,000-scale) prepared by the USGS in cooperation with the U.S. Water Resources Council.

Other Sources for information about hydrologic unit boundaries:

EPA's Surf Your Watershed web page provides a service to help you locate, use, and share environmental information about your place.

USGS WRD's Office of Surface Water web page offers information on surface-water and sediment data.  It includes data, publications, and information on equipment, facilities, and techniques.

USGS Water Science for Schools offers information on many aspects of water, along with pictures, data, maps, and an interactive center where you can give opinions and test your water knowledge.

Metadata:

What follows is very detailed technical information about this map layer. This is often called metadata. Metadata (or "data about data") describe the content, quality, condition, and other characteristics of data. Metadata are used to organize and maintain investments in data, to provide information to data catalogs and clearinghouses, and to aid data transfers. The Federal Geographic Data Committee (FGDC) publishes the Content Standard for Digital Geospatial Metadata. Many organizations within and outside of the federal government have adopted the FGDC metadata standard and are using automated indexing and serving mechanisms to provide access to their holdings through the Internet. Visit the FGDC Clearinghouse to learn more about how metadata is used in clearinghouses and to search for other data sets.

• 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: John Watermolen, 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

Online_Linkage: <http://www-atlas.usgs.gov/atlasftp.html>

Description:

Abstract:

This file contains hydrologic unit boundaries and codes for the conterminous United States along with Alaska, Hawaii, 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.

Purpose:

Due to its small scale (1:2,000,000), this file is intended primarily for display and analysis of regional and national data rather than for analysis of specific data. The file has been updated for inclusion in the National Atlas of the United States of America and to match the base data created for the National Atlas.

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 data set in nonproprietary form, as well as in ARC/INFO format, this metadata file may include some ARC/INFO-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 ARC/INFO 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 plot of the data.

Also in the ARC/INFO version, imbedded in the INFO file is the HUCS_2M.TRACE file, which points to the next downstream cataloging unit for each basin. If a basin flows into another cataloging unit, that unit's code is given for the HUC_TO item. Not all basins flow into other basins; in these cases, the following codes were used for HUC_TO:

  HUC_TO     Meaning

  0          Ocean

  1          Flows across a national border

  2          Closed drainage

A second imbedded file is HUCS_2M.AML_INDEX, which is a listing containing an index of all user-defined items in the .PAT and .AAT files.

Note: HUCS_2M.TRACE and HUCS_2M.AML_INDEX are accessed through INFO by selecting for the file. These files have not been updated for Version 2.0. INDEX_HUC.AML, which creates the index file, is also available through INFO.

Time_Period_of_Content:

Time_Period_Information:

Single_Date/Time:

Calendar_Date: 19981001

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: 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: Alaska

Place_Keyword: Hawaii

Place_Keyword: Puerto Rico

Place_Keyword: Virgin Islands

Access_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.

Use_Constraints: None

Point_of_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: John Watermolen

Contact_Organization: U.S. Geological Survey

Contact_Position: Cartographer

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, x134

Contact_Facsimile_Telephone: (608) 238-9334

Contact_Electronic_Mail_Address: jmwater@usgs.gov

Data_Set_Credit:

Others who have helped with this data set 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, ARC/INFO version 7.1.1.

Cross_Reference:

Citation_Information:

Originator: U.S. Geological Survey

Publication_Date: 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 ARC/INFO command labelerrors. All polygons were checked for closure and intersections by using the ARC/INFO 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 data set 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 data set 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 data set.

Source_Information:

Source_Citation:

Citation_Information:

Originator:

Seaber, Paul R., Kapinos, F. Paul, and Knapp, George L., U.S. Geological Survey

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: publication date

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: publication date

Source_Citation_Abbreviation: NAHydro

Source_Contribution: Coastline 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, Hyattesville, MD., which digitizes materials on contract for NMD.

e) Digital data from Automated Datatron was converted to an ARC/INFO 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 ARC/INFO, 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 ARC/INFO, 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:

The 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 HUC_INDEX.AML.

Source_Used_Citation_Abbreviation: HUCS11

Source_Used_Citation_Abbreviation: RF1

Process_Date: 1994

Source_Produced_Citation_Abbreviation: HUCS111

Process_Step:

Process_Description:

Using ARC/INFO, 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 data set 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. This same procedure also indexed the coverage on all user-defined items in the .PAT and .AAT files. A listing can be found in the file, HUCS_2M.AML_INDEX (imbedded in the INFO file).

The attributes Error_type, Reg_name, Map_label, Catalog_Unit_Nam, and Catalog_unit_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 ARC/INFO 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

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: 6378206.4

Denominator_of_Flattening_Ratio: 294.98

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: U.S. Geological Survey

Attribute:

Attribute_Label: Shape

Attribute_Definition:

The representation of the entity in the data

Attribute_Definition_Source: U.S. Geological Survey

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

Attribute_Definition_Source: U.S. Geological Survey

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

Attribute_Definition_Source: U.S. Geological Survey

Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 0.004

Range_Domain_Maximum: 41.175

Attribute:

Attribute_Label: US_HUCS_ALB# or Hucs00m020

Attribute_Definition: Internal feature number

Attribute_Definition_Source: U.S. Geological Survey

Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 2

Range_Domain_Maximum: 5348

Attribute:

Attribute_Label: US_HUCS_ALB-ID or Hucs00m020

Attribute_Definition: User-assigned feature number

Attribute_Definition_Source: U.S. Geological Survey

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: U.S. Geological Survey

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: U.S. Geological Survey

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: U.S. Geological Survey

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: U.S. Geological Survey

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: U.S. Geological Survey

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: U.S. Geological Survey

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: U.S. Geological Survey

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: U.S. Geological Survey

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: U.S. Geological Survey

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: U.S. Geological Survey

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: U.S. Geological Survey

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: U.S. Geological Survey

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: U.S. Geological Survey

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 2150 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: U.S. Geological Survey

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: U.S. Geological Survey

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: U.S. Geological Survey

Attribute:

Attribute_Label: Shape

Attribute_Definition:

The representation of the entity in the data

Attribute_Definition_Source: U.S. Geological Survey

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 number of the from-node

Attribute_Definition_Source: U.S. Geological Survey

Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 1

Range_Domain_Maximum: 9039

Attribute:

Attribute_Label: Tnode# or Tnode_

Attribute_Definition: Internal number of the to-node

Attribute_Definition_Source: U.S. Geological Survey

Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 1

Range_Domain_Maximum: 9039

Attribute:

Attribute_Label: Lpoly# or Lpoly_

Attribute_Definition:

Internal number of the polygon to the left of the arc

Attribute_Definition_Source: U.S. Geological Survey

Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 1

Range_Domain_Maximum: 5348

Attribute:

Attribute_Label: Rpoly# or Rpoly_

Attribute_Definition:

Internal number of the polygon to the right of the arc

Attribute_Definition_Source: U.S. Geological Survey

Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 1

Range_Domain_Maximum: 5347

Attribute:

Attribute_Label: Length

Attribute_Definition:

The length of the arc in coverage units.

Attribute_Definition_Source: U.S. Geological Survey

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: U.S. Geological Survey

Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 1

Range_Domain_Maximum: 11576

Attribute:

Attribute_Label: US_HUCS_ALB-ID or Hucs00m020

Attribute_Definition: User-assigned feature number

Attribute_Definition_Source: U.S. Geological Survey

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: U.S. Geological Survey

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: U.S. Geological Survey

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)

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 <http://mapping.usgs.gov/esic/esic_index.html>

Distribution_Liability:

Although these data have been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of this data, software, or related materials.

Metadata_Reference_Information:

Metadata_Date: 19990406

Metadata_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: U.S. Geological Survey

Contact_Person: John Watermolen

Contact_Position: Cartographer

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 x134

Contact_Facsimile_Telephone: (608) 238-9334

Contact_Electronic_Mail_Address: jmwater@usgs.gov

Metadata_Standard_Name:

FGDC Content Standards for Digital Geospatial Metadata

Metadata_Standard_Version: FGDC-STD-001-1998

Metadata_Access_Constraints: none

Metadata_Use_Constraints: none