Hydrography - NHD/WBD/NHDPlus HR - Data Dictionary Report

FEATURE CLASS

NHDArea: Areal hydrographic landmark features.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
AreaSqKm Area of feature in square kilometers based on Albers Equal Area projection. Double true 0 Computed.
Elevation The vertical distance from a given datum. Double true 0 ElevationRange Stage of the water elevation is encoded in the FCode.
FCode Feature Code. Numeric value that encodes a set of characteristics for a type of feature. This five-digit code has two parts: the first three digits encode the feature type (FType); the last two digits encode values for a unique set of characteristics associated with the feature type. The set of characteristics may be single valued or multi-valued. Long Integer true 0 default value varies, depending on feature
FDate Date of last feature modification. Date false 0 8
FType Feature Type. Numeric value that encodes a type of feature, represented as a three-digit code. For further refinement of the feature type classification, see FCode. Long Integer false 0 default value varies, depending on feature
GNIS_ID A permanent, unique number assigned by the Geographic Names Information System (GNIS) to a geographic feature name for the sole purpose of uniquely identifying that name application as a record in any information system database, dataset, file, or document Text true 10 GNIS_ID = "null" if no name is associated with the feature. Removed from WBD as of version 2.3 schema.
GNIS_Name The Geographic Names Information System (GNIS) assigned proper name, specific term, or expression by which a particular geographic entity is known. Text true 65
NHDPlusID NHDPlus HR Unique identifier of a NHDFlowline feature. Found in NHDPlus HR Only. Double true This field only exists when NHD feature classes are brought into NHDPlus HR.
OBJECTID Internal feature or event number. OBJECTID false
Permanent_Identifier A 40-character globally unique ID (GUID) value that uniquely identifies the occurrence of each feature or event in The National Map. Text false 40
Resolution Source resolution. Long Integer false 0 Resolution Currently NHD is available as separate resolutions. Domain values: Local > 1:12,000 High 1:24,000/12,000 Medium 1:100,000
Shape Feature geometry. Geometry true
Shape_Area Area of feature in map units squared. Double true 0
Shape_Length Length of the feature, which may differ from the field measured length due to differences in calculation. Units are map units. Double true 0 All features should have a positive integer value.
VPUID Vector Processing Unit Identifier. Found in NHDPlus HR only. Text true 8 This field only exists when NHD feature classes are brought into NHDPlus HR.
VisibilityFilter Allows for filtering of features for usage of vector data at approximate scales. Long Integer false VisibilityFilter 0

SubTypes of NHDArea

SubTypeDescriptionDefinition
307Area to be SubmergedKnown extent of the intended lake that will be created behind a dam under construction.
312BayInletWater opening that is an opening into the sea/ocean into the land, or of an estuary, lake, or river into its shore.
318BridgeStructure spanning and providing passage over a waterway, railroad, or other obstacle.
336CanalDitchArtificial open waterway constructed to transport water, to irrigate or drain land, to connect two or more bodies of water, or to serve as a waterway for watercraft.
343DamWeirBarrier constructed to control the flow or raise the level of water.
362FlumeOpen, inclined, artificial channel constructed of wood, metal, or concrete; generally elevated.
364ForeshorePart of a seashore between high-water and low-water marks.
398Lock ChamberEnclosure on a waterway used to raise/lower vessels as they pass from one level to another.
403Inundation AreaArea of land subject to flooding.
431RapidsArea of swift current in a stream or river, characterized by standing waves or by boulders and rocks.
445SeaOceanGreat body of salt water that covers much of the earth.
455SpillwayConstructed passage for surplus water to run over or around a dam.
460StreamRiverBody of flowing water.
461Submerged StreamOld river course inundated by an impounded water body.
484WashUsually dry portion of a stream bed that contains water only during or after a local rainstorm or heavy snowmelt.
485Water IntakeOutflowStructure through which water enters or exits a conduit.
537Area of Complex ChannelsArea where a stream or river flows in an intricate network of interlacing channels.
568LeveeA natural or manmade embankment along the edge of a stream/river, canal/ditch, or waterbody, that protects the surrounding land from flooding.



NHDAreaEventFC: Area event must be tied to a NHDWaterbody. They cannot be linked to a linear feature or point feature. Area events are built into the NHD Model but are not accepted back into the National Database. They are meant to be used on an individual basis.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
EventDate Date an event was created or modified. Date true 0 8
EventType Type of feature reference as an event. Long Integer false Area Event Type Domain
FeatureClassRef NHD feature class that holds FeatureComID. Long Integer true 0
FeatureDetailURL URL where detailed event entity data can be found. Text true 255
Feature_Permanent_Identifier Permanent_Identifier of NHD feature that the event is referenced to. Text false 40
OBJECTID Internal feature or event number. OBJECTID false
Permanent_Identifier A 40-character globally unique ID (GUID) value that uniquely identifies the occurrence of each feature or event in The National Map. Text false 40
ReachCode Unique identifier. The first eight digits are the WBD_HUC8. The next six digits are randomly assigned, sequential numbers that are unique within a HUC8. Text true 14 For event feature classes, this value is the ReachCode on which the event is located.
ReachResolution Source resolution. Long Integer false 0 Currently NHD is available as separate resolutions. Domain of values: Local > 1:12,000 High 1:24,000/12,000 Medium: 1:100,000
ReachSMDate Reach spatial modification date. Date true 0 8 The ReachCodeMaintenance table is updated by the NHD Update Tool. When a geometric edit is performed on a feature that contains a ReachCode (NHDFlowline or NHDWaterbody), the NHDReachCodeMaintenance table is updated to the current date to reflect the last spatial modification (SM) date of the associated ReachCode. Any previous records for that Resolution (Medium or High, depending on the target feature class resolution) are overwritten. The Permanent_Identifier field is unique to this table and is not related to NHDFlowline or Waterbody features. The GNIS_ID and GNIS_Name are updated, as these are unique per ReachCode. MValue updates are not considered spatial modifications and thus do not trigger ReachSMDate updates. For events (NHDPointEvent, NHDLineEvent, NHDAreaEvent), when an event is created by the Hydrography Event Management (HEM) Tool, the tool pulls the current ReachSMDate from the ReachCodeMaintenance table for the ReachCode the event is associated with. So, if underlying hydrography features are updated, and events are not, the ReachSMDate in the event table will be out of date in relation to the current hydrography. Users can either synchronize their events using the HEM Tool or they may not, depending on their needs. For example, a user may not want to synchronize their events to the current hydrography if a study was performed on a certain version of the NHD.
Shape Feature geometry. Geometry true
Shape_Area Area of feature in map units squared. Double true 0
Shape_Length Length of the feature, which may differ from the field measured length due to differences in calculation. Units are map units. Double true 0 All features should have a positive integer value.
Source_DataDesc Brief narrative of the source dataset. Text true 100
Source_FeatureID Identifier of the feature or event in the source dataset. Text true 100
Source_Originator Name of the organization or individual that developed the source dataset. Text true 130




NHDFlowline: NHDFlowlines consist of routes that make up a linear surface water drainage network. Flowlines have a reach code and a measure, allowing for the establishment of upstream/downstream relationships. This network allows for powerful analysis and modeling capabilities.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
Enabled An indication of whether a feature can participate in a geometric network. Short Integer true "Enabled" attribute values
FCode Feature Code. Numeric value that encodes a set of characteristics for a type of feature. This five-digit code has two parts: the first three digits encode the feature type (FType); the last two digits encode values for a unique set of characteristics associated with the feature type. The set of characteristics may be single valued or multi-valued. Long Integer true 0 default value varies, depending on feature
FDate Date of last feature modification. Date false 0 8
FType Feature Type. Numeric value that encodes a type of feature, represented as a three-digit code. For further refinement of the feature type classification, see FCode. Long Integer false 0 default value varies, depending on feature
FlowDir Direction of flow relative to coordinate order. Long Integer false HydroFlowDirections 0 Domain of values: With digitized Uninitialized
GNIS_ID A permanent, unique number assigned by the Geographic Names Information System (GNIS) to a geographic feature name for the sole purpose of uniquely identifying that name application as a record in any information system database, dataset, file, or document Text true 10 GNIS_ID = "null" if no name is associated with the feature. Removed from WBD as of version 2.3 schema.
GNIS_Name The Geographic Names Information System (GNIS) assigned proper name, specific term, or expression by which a particular geographic entity is known. Text true 65
InNetwork Identifies the subset of the NHDFlowline features that will be used/included in NHDPlus. Short Integer true 0 NoYesDomain InNetwork is an attribute that the user can set to define the subset of the NHDFlowline features that will be used/included in NHDPlus. Yes = In network, Features included in the NHDPlus network. No = Out of network - Features not included in the NHDPlus network.
LengthKM Length of linear feature. Value is computed when data are in Albers Equal Area projection. Double true 0 Computed
MainPath The main stream path that tributary streams converge to or diverge from. Long Integer true 0 MainPath 0
NHDPlusID NHDPlus HR Unique identifier of a NHDFlowline feature. Found in NHDPlus HR Only. Double true This field only exists when NHD feature classes are brought into NHDPlus HR.
OBJECTID Internal feature or event number. OBJECTID false
Permanent_Identifier A 40-character globally unique ID (GUID) value that uniquely identifies the occurrence of each feature or event in The National Map. Text false 40
ReachCode Unique identifier. The first eight digits are the WBD_HUC8. The next six digits are randomly assigned, sequential numbers that are unique within a HUC8. Text true 14 Required for all NHDFlowlines. NHDWaterbody and NHDPoint feature classes allow reach codes, but do not require them.
Resolution Source resolution. Long Integer false 0 Resolution Currently NHD is available as separate resolutions. Domain values: Local > 1:12,000 High 1:24,000/12,000 Medium 1:100,000
Shape Feature geometry. Geometry true
Shape_Length Length of the feature, which may differ from the field measured length due to differences in calculation. Units are map units. Double true 0 All features should have a positive integer value.
VPUID Vector Processing Unit Identifier. Found in NHDPlus HR only. Text true 8 This field only exists when NHD feature classes are brought into NHDPlus HR.
VisibilityFilter Allows for filtering of features for usage of vector data at approximate scales. Long Integer false VisibilityFilter 0
WBArea_Permanent_Identifier Permanent_Identifier of the waterbody through which the flowline flows. Text true 40

SubTypes of NHDFlowline

SubTypeDescriptionDefinition
334ConnectorKnown, but unspecific, connection between two nonadjacent network segments.
336CanalDitchArtificial open waterway constructed to transport water, to irrigate or drain land, to connect two or more bodies of water, or to serve as a waterway for watercraft.
420Underground ConduitUnderground passage of surface water.
428PipelineClosed conduit with pumps, valves, and control devices, for conveying fluids, gases, or finely divided solids.
460StreamRiverBody of flowing water.
468DrainagewayDrainageway features are flowlines delineated where terrain modelling indicates potential headwater drainage but no channel is detectable. The drainageway code must only be applied at the initiation of flowlines or confluence of other drainageway features. The drainageway code must not be applied downstream of other non-drainageway NHD flowlines or waterbody features.
558ArtificialPathAbstraction to facilitate hydrologic modeling through open water bodies and along coastal and Great Lakes shorelines and to act as a surrogate for lakes and other water bodies.
566CoastlineLine that follows the main outline of the land, including bays, but crosses rivers at their mouth. In the NHD, the outline of selected coastal islands are included as part of the coastline.



NHDLine: NHDLines represent linear NHD hydrographic landmark features used for cartographic representation.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
FCode Feature Code. Numeric value that encodes a set of characteristics for a type of feature. This five-digit code has two parts: the first three digits encode the feature type (FType); the last two digits encode values for a unique set of characteristics associated with the feature type. The set of characteristics may be single valued or multi-valued. Long Integer true 0 default value varies, depending on feature
FDate Date of last feature modification. Date false 0 8
FType Feature Type. Numeric value that encodes a type of feature, represented as a three-digit code. For further refinement of the feature type classification, see FCode. Long Integer false 0 default value varies, depending on feature
GNIS_ID A permanent, unique number assigned by the Geographic Names Information System (GNIS) to a geographic feature name for the sole purpose of uniquely identifying that name application as a record in any information system database, dataset, file, or document Text true 10 GNIS_ID = "null" if no name is associated with the feature. Removed from WBD as of version 2.3 schema.
GNIS_Name The Geographic Names Information System (GNIS) assigned proper name, specific term, or expression by which a particular geographic entity is known. Text true 65
LengthKM Length of linear feature. Value is computed when data are in Albers Equal Area projection. Double true 0 Computed
NHDPlusID NHDPlus HR Unique identifier of a NHDFlowline feature. Found in NHDPlus HR Only. Double true This field only exists when NHD feature classes are brought into NHDPlus HR.
OBJECTID Internal feature or event number. OBJECTID false
Permanent_Identifier A 40-character globally unique ID (GUID) value that uniquely identifies the occurrence of each feature or event in The National Map. Text false 40
Resolution Source resolution. Long Integer false 0 Resolution Currently NHD is available as separate resolutions. Domain values: Local > 1:12,000 High 1:24,000/12,000 Medium 1:100,000
Shape Feature geometry. Geometry true
Shape_Length Length of the feature, which may differ from the field measured length due to differences in calculation. Units are map units. Double true 0 All features should have a positive integer value.
VPUID Vector Processing Unit Identifier. Found in NHDPlus HR only. Text true 8 This field only exists when NHD feature classes are brought into NHDPlus HR.
VisibilityFilter Allows for filtering of features for usage of vector data at approximate scales. Long Integer false VisibilityFilter 0

SubTypes of NHDLine

SubTypeDescriptionDefinition
318BridgeStructure spanning and providing passage over a waterway, railroad, or other obstacle.
343DamWeirBarrier constructed to control the flow or raise the level of water.
362FlumeOpen, inclined, artificial channel constructed of wood, metal, or concrete; generally elevated.
369GateStructure that may be swung, drawn, or lowered, to block an entrance or passageway.
398Lock ChamberEnclosure on a waterway used to raise/lower vessels as they pass from one level to another.
411Nonearthen ShoreStructure built of stone, concrete, or other building material, that borders a body of water.
434ReefChain of rocks or coral at, or near, the surface of water.
450SinkRisePlace at which a stream disappears underground or reappears at the surface in a karst area.
478TunnelUnderground or underwater passage.
483WallUpright structure of masonry, wood, plaster, or other building material serving to enclose, divide, or protect an area.
487WaterfallVertical or near vertical descent of water over a step or ledge in the bed of a river.
503Sounding Datum LineLine representing the tidal datum to which bathymetric contours are referenced.
568LeveeA natural or manmade embankment along the edge of a stream/river, canal/ditch, or waterbody, that protects the surrounding land from flooding.



NHDLineEventFC: Linear Events are used to attach information about a flowline segment to the NHD. Linear events are built into the NHD Model but are not accepted back into the National Database. They are meant to be used on an individual basis. They also need a from and to location and a reachcode.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
EventDate Date an event was created or modified. Date true 0 8
EventOffset Distance from the network to be used to display event. Double true 0 Negative offsets display the event to the left of the network and positive offsets display the event to the right of the line. Offsets are useful for displaying overlapping events.
EventType Type of feature reference as an event. Long Integer false Line Event Type
FMeasure Measure along the reach, in percent from downstream end, where a linear event begins (from). Double false 0
FeatureClassRef NHD feature class that holds FeatureComID. Long Integer true 0
FeatureDetailURL URL where detailed event entity data can be found. Text true 255
Feature_Permanent_Identifier Permanent_Identifier of NHD feature that the event is referenced to. Text false 40
OBJECTID Internal feature or event number. OBJECTID false
Permanent_Identifier A 40-character globally unique ID (GUID) value that uniquely identifies the occurrence of each feature or event in The National Map. Text false 40
ReachCode Unique identifier. The first eight digits are the WBD_HUC8. The next six digits are randomly assigned, sequential numbers that are unique within a HUC8. Text true 14 For event feature classes, this value is the ReachCode on which the event is located.
ReachResolution Source resolution. Long Integer false 0 Currently NHD is available as separate resolutions. Domain of values: Local > 1:12,000 High 1:24,000/12,000 Medium: 1:100,000
ReachSMDate Reach spatial modification date. Date true 0 8 The ReachCodeMaintenance table is updated by the NHD Update Tool. When a geometric edit is performed on a feature that contains a ReachCode (NHDFlowline or NHDWaterbody), the NHDReachCodeMaintenance table is updated to the current date to reflect the last spatial modification (SM) date of the associated ReachCode. Any previous records for that Resolution (Medium or High, depending on the target feature class resolution) are overwritten. The Permanent_Identifier field is unique to this table and is not related to NHDFlowline or Waterbody features. The GNIS_ID and GNIS_Name are updated, as these are unique per ReachCode. MValue updates are not considered spatial modifications and thus do not trigger ReachSMDate updates. For events (NHDPointEvent, NHDLineEvent, NHDAreaEvent), when an event is created by the Hydrography Event Management (HEM) Tool, the tool pulls the current ReachSMDate from the ReachCodeMaintenance table for the ReachCode the event is associated with. So, if underlying hydrography features are updated, and events are not, the ReachSMDate in the event table will be out of date in relation to the current hydrography. Users can either synchronize their events using the HEM Tool or they may not, depending on their needs. For example, a user may not want to synchronize their events to the current hydrography if a study was performed on a certain version of the NHD.
Shape Feature geometry. Geometry true
Shape_Length Length of the feature, which may differ from the field measured length due to differences in calculation. Units are map units. Double true 0 All features should have a positive integer value.
Source_DataDesc Brief narrative of the source dataset. Text true 100
Source_FeatureID Identifier of the feature or event in the source dataset. Text true 100
Source_Originator Name of the organization or individual that developed the source dataset. Text true 130
TMeasure Measure along the reach, in percent from downstream end, where a linear event ends (to). Double false 0




NHDPlusBurnLineEvent: Events describing the parts of NHDFlowline features used for hydro-enforcement

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
Burn 0 (no) or 1 (yes) if line will be used for hydro-enforcement Short Integer true 0 NoYesDomain
BurnLengKm Length of BurnLineEvent feature Double true 0
Catchment 0 (no) or 1 (yes) if line will receive catchment Short Integer true 0 NoYesDomain
FromMeas Downstream BurnLineEvent Measure (m-value) Double true 0
GridCode Unique, compact identification number assigned to a Sink point Long Integer true 0
NHDPlusID NHDPlus HR Unique identifier of a NHDFlowline feature. Found in NHDPlus HR Only. Double true This field only exists when NHD feature classes are brought into NHDPlus HR.
OBJECTID Internal feature or event number. OBJECTID false
RPUID Raster Processing Unit Identifier Text true 8
ReachCode Unique identifier. The first eight digits are the WBD_HUC8. The next six digits are randomly assigned, sequential numbers that are unique within a HUC8. Text true 14 For event feature classes, this value is the ReachCode on which the event is located.
Shape Feature geometry. Geometry true
Shape_Length Length of the feature, which may differ from the field measured length due to differences in calculation. Units are map units. Double true 0 All features should have a positive integer value.
StatusFlag Flag reserved for use during NHDPlus Build/Refresh Process Text true 1 StatusFlag Domain
ToMeas Upstream BurnLineEvent Measure (m-value) Double true 0
VPUID Vector Processing Unit Identifier. Found in NHDPlus HR only. Text true 8 This field only exists when NHD feature classes are brought into NHDPlus HR.




NHDPlusBurnWaterbody: NHDWaterbody and NHDArea features used for hydro-enforcement

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
Burn 0 (no) or 1 (yes) if line will be used for hydro-enforcement Short Integer true 0 NoYesDomain
NHDPlusID NHDPlus HR Unique identifier of a NHDFlowline feature. Found in NHDPlus HR Only. Double true This field only exists when NHD feature classes are brought into NHDPlus HR.
OBJECTID Internal feature or event number. OBJECTID false
OnOffNet On/Off network flag (1 = On network, 0 = Off network) Short Integer true 0 NoYesDomain Alias "OnNetwork"
PurpCode Code describing purpose of feature Text true 2 PurposeCode Domain Alias "PurposeCode"
Shape Feature geometry. Geometry true
Shape_Area Area of feature in map units squared. Double true 0
Shape_Length Length of the feature, which may differ from the field measured length due to differences in calculation. Units are map units. Double true 0 All features should have a positive integer value.
SourceFC Source NHD Feature Class – "NHDWaterbody", "NHDArea." Text true 20 Alias, "SourceFeatureClass."
VPUID Vector Processing Unit Identifier. Found in NHDPlus HR only. Text true 8 This field only exists when NHD feature classes are brought into NHDPlus HR.




NHDPlusCatchment: Feature class that contains a catchment polygon for an NHDFlowline feature or a sink feature

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
AreaSqKm AreaSqKm is calculated at the hydrologic unit from the intrinsic area value maintained by the GIS software; therefore, the square kilometer values may vary from user calculations, depending on the projection of the data. North American Albers Equal Area Conic, North American Datum 1983 is the default projection. Double true
GridCode Unique, compact identification number assigned to a Sink point Long Integer true 0
NHDPlusID NHDPlus HR Unique identifier of a NHDFlowline feature. Found in NHDPlus HR Only. Double true This field only exists when NHD feature classes are brought into NHDPlus HR.
OBJECTID Internal feature or event number. OBJECTID false
Shape Feature geometry. Geometry true
Shape_Area Area of feature in map units squared. Double true 0
Shape_Length Length of the feature, which may differ from the field measured length due to differences in calculation. Units are map units. Double true 0 All features should have a positive integer value.
SourceFC Source NHD Feature Class – "NHDWaterbody", "NHDArea." Text true 20 Alias, "SourceFeatureClass."
VPUID Vector Processing Unit Identifier. Found in NHDPlus HR only. Text true 8 This field only exists when NHD feature classes are brought into NHDPlus HR.




NHDPlusLandSea: Polygons used for hydro-enforcement along the NHD coastline

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
Land A numeric code to identify land/sea/estuary area Short Integer true 0 LandSea Domain 1
NHDPlusID NHDPlus HR Unique identifier of a NHDFlowline feature. Found in NHDPlus HR Only. Double true This field only exists when NHD feature classes are brought into NHDPlus HR.
OBJECTID Internal feature or event number. OBJECTID false
Shape Feature geometry. Geometry true
Shape_Area Area of feature in map units squared. Double true 0
Shape_Length Length of the feature, which may differ from the field measured length due to differences in calculation. Units are map units. Double true 0 All features should have a positive integer value.
VPUID Vector Processing Unit Identifier. Found in NHDPlus HR only. Text true 8 This field only exists when NHD feature classes are brought into NHDPlus HR.




NHDPlusSink: Point locations of sinks used for hydro-enforcement

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
Burn 0 (no) or 1 (yes) if line will be used for hydro-enforcement Short Integer true 0 NoYesDomain
Catchment 0 (no) or 1 (yes) if line will receive catchment Short Integer true 0 NoYesDomain
FeatureID ID of feature in another feature class (ComID, Gaz_ID, PolyID) Double true 0
GridCode Unique, compact identification number assigned to a Sink point Long Integer true 0
NHDPlusID NHDPlus HR Unique identifier of a NHDFlowline feature. Found in NHDPlus HR Only. Double true This field only exists when NHD feature classes are brought into NHDPlus HR.
OBJECTID Internal feature or event number. OBJECTID false
PurpCode Code describing purpose of feature Text true 2 PurposeCode Domain Alias "PurposeCode"
RPUID Raster Processing Unit Identifier Text true 8
Shape Feature geometry. Geometry true
SourceFC Source NHD Feature Class – "NHDWaterbody", "NHDArea." Text true 20 Alias, "SourceFeatureClass."
StatusFlag Flag reserved for use during NHDPlus Build/Refresh Process Text true 1 StatusFlag Domain
VPUID Vector Processing Unit Identifier. Found in NHDPlus HR only. Text true 8 This field only exists when NHD feature classes are brought into NHDPlus HR.




NHDPlusWall: Lines used as walls in hydro-enforcement

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
Burn 0 (no) or 1 (yes) if line will be used for hydro-enforcement Short Integer true 0 NoYesDomain
NHDPlusID NHDPlus HR Unique identifier of a NHDFlowline feature. Found in NHDPlus HR Only. Double true This field only exists when NHD feature classes are brought into NHDPlus HR.
OBJECTID Internal feature or event number. OBJECTID false
Shape Feature geometry. Geometry true
Shape_Length Length of the feature, which may differ from the field measured length due to differences in calculation. Units are map units. Double true 0 All features should have a positive integer value.
VPUID Vector Processing Unit Identifier. Found in NHDPlus HR only. Text true 8 This field only exists when NHD feature classes are brought into NHDPlus HR.
WallSource Source used for wall Text true 30




NHDPoint: NHDPoints contain points representing NHD hydrographic landmark features.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
FCode Feature Code. Numeric value that encodes a set of characteristics for a type of feature. This five-digit code has two parts: the first three digits encode the feature type (FType); the last two digits encode values for a unique set of characteristics associated with the feature type. The set of characteristics may be single valued or multi-valued. Long Integer true 0 default value varies, depending on feature
FDate Date of last feature modification. Date false 0 8
FType Feature Type. Numeric value that encodes a type of feature, represented as a three-digit code. For further refinement of the feature type classification, see FCode. Long Integer false 0 default value varies, depending on feature
GNIS_ID A permanent, unique number assigned by the Geographic Names Information System (GNIS) to a geographic feature name for the sole purpose of uniquely identifying that name application as a record in any information system database, dataset, file, or document Text true 10 GNIS_ID = "null" if no name is associated with the feature. Removed from WBD as of version 2.3 schema.
GNIS_Name The Geographic Names Information System (GNIS) assigned proper name, specific term, or expression by which a particular geographic entity is known. Text true 65
NHDPlusID NHDPlus HR Unique identifier of a NHDFlowline feature. Found in NHDPlus HR Only. Double true This field only exists when NHD feature classes are brought into NHDPlus HR.
OBJECTID Internal feature or event number. OBJECTID false
Permanent_Identifier A 40-character globally unique ID (GUID) value that uniquely identifies the occurrence of each feature or event in The National Map. Text false 40
ReachCode Unique identifier. The first eight digits are the WBD_HUC8. The next six digits are randomly assigned, sequential numbers that are unique within a HUC8. Text true 14 Required for all NHDFlowlines. NHDWaterbody and NHDPoint feature classes allow reach codes, but do not require them.
Resolution Source resolution. Long Integer false 0 Resolution Currently NHD is available as separate resolutions. Domain values: Local > 1:12,000 High 1:24,000/12,000 Medium 1:100,000
Shape Feature geometry. Geometry true
VPUID Vector Processing Unit Identifier. Found in NHDPlus HR only. Text true 8 This field only exists when NHD feature classes are brought into NHDPlus HR.

SubTypes of NHDPoint

SubTypeDescriptionDefinition
343DamWeirBarrier constructed to control the flow or raise the level of water.
367Gaging StationStructure used to measure the characteristics of a hydrographic feature.
369GateStructure that may be swung, drawn, or lowered, to block an entrance or passageway.
398Lock ChamberEnclosure on a waterway used to raise/lower vessels as they pass from one level to another.
431RapidsArea of swift current in a stream or river, characterized by standing waves or by boulders and rocks.
436ReservoirConstructed basin formed to contain water or other liquids.
441RockConcreted mass of stony material.
450SinkRisePlace at which a stream disappears underground or reappears at the surface in a karst area.
458SpringSeepPlace where water issues from the ground naturally.
485Water IntakeOutflowStructure through which water enters or exits a conduit.
487WaterfallVertical or near vertical descent of water over a step or ledge in the bed of a river.
488WellPit or hole, dug or bored into the earth for the extraction of water or other fluids, or gases.



NHDPointEventFC: Point events are tied to a specific location on a stream network by a reachcode and a measure. While several types of Point Events are accepted back into the National Database, additional Point Event Types may be used on an individual basis.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
EventDate Date an event was created or modified. Date true 0 8
EventOffset Distance from the network to be used to display event. Double true 0 Negative offsets display the event to the left of the network and positive offsets display the event to the right of the line. Offsets are useful for displaying overlapping events.
EventType Type of feature reference as an event. Long Integer false Point Event Type
FeatureClassRef NHD feature class that holds FeatureComID. Long Integer true 0
FeatureDetailURL URL where detailed event entity data can be found. Text true 255
Feature_Permanent_Identifier Permanent_Identifier of NHD feature that the event is referenced to. Text false 40
Measure Measure along the reach, in percent from downstream end, where a point event is located. Double false 0
OBJECTID Internal feature or event number. OBJECTID false
Permanent_Identifier A 40-character globally unique ID (GUID) value that uniquely identifies the occurrence of each feature or event in The National Map. Text false 40
ReachCode Unique identifier. The first eight digits are the WBD_HUC8. The next six digits are randomly assigned, sequential numbers that are unique within a HUC8. Text true 14 For event feature classes, this value is the ReachCode on which the event is located.
ReachResolution Source resolution. Long Integer false 0 Currently NHD is available as separate resolutions. Domain of values: Local > 1:12,000 High 1:24,000/12,000 Medium: 1:100,000
ReachSMDate Reach spatial modification date. Date true 0 8 The ReachCodeMaintenance table is updated by the NHD Update Tool. When a geometric edit is performed on a feature that contains a ReachCode (NHDFlowline or NHDWaterbody), the NHDReachCodeMaintenance table is updated to the current date to reflect the last spatial modification (SM) date of the associated ReachCode. Any previous records for that Resolution (Medium or High, depending on the target feature class resolution) are overwritten. The Permanent_Identifier field is unique to this table and is not related to NHDFlowline or Waterbody features. The GNIS_ID and GNIS_Name are updated, as these are unique per ReachCode. MValue updates are not considered spatial modifications and thus do not trigger ReachSMDate updates. For events (NHDPointEvent, NHDLineEvent, NHDAreaEvent), when an event is created by the Hydrography Event Management (HEM) Tool, the tool pulls the current ReachSMDate from the ReachCodeMaintenance table for the ReachCode the event is associated with. So, if underlying hydrography features are updated, and events are not, the ReachSMDate in the event table will be out of date in relation to the current hydrography. Users can either synchronize their events using the HEM Tool or they may not, depending on their needs. For example, a user may not want to synchronize their events to the current hydrography if a study was performed on a certain version of the NHD.
Shape Feature geometry. Geometry true
Source_DataDesc Brief narrative of the source dataset. Text true 100
Source_FeatureID Identifier of the feature or event in the source dataset. Text true 100
Source_Originator Name of the organization or individual that developed the source dataset. Text true 130




NHDWaterbody: Features representing areal NHD hydrographic waterbody features. Some Waterbody features such as LakePond, Reservoir, and Estuary must have a reachcode. SwampMarsh may have a reachcode. Ice Mass and Playa do not have reachcodes.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
AreaSqKm Area of feature in square kilometers based on Albers Equal Area projection. Double true 0 Computed.
Elevation The vertical distance from a given datum. Double true 0 ElevationRange Stage of the water elevation is encoded in the FCode.
FCode Feature Code. Numeric value that encodes a set of characteristics for a type of feature. This five-digit code has two parts: the first three digits encode the feature type (FType); the last two digits encode values for a unique set of characteristics associated with the feature type. The set of characteristics may be single valued or multi-valued. Long Integer true 0 default value varies, depending on feature
FDate Date of last feature modification. Date false 0 8
FType Feature Type. Numeric value that encodes a type of feature, represented as a three-digit code. For further refinement of the feature type classification, see FCode. Long Integer false 0 default value varies, depending on feature
GNIS_ID A permanent, unique number assigned by the Geographic Names Information System (GNIS) to a geographic feature name for the sole purpose of uniquely identifying that name application as a record in any information system database, dataset, file, or document Text true 10 GNIS_ID = "null" if no name is associated with the feature. Removed from WBD as of version 2.3 schema.
GNIS_Name The Geographic Names Information System (GNIS) assigned proper name, specific term, or expression by which a particular geographic entity is known. Text true 65
NHDPlusID NHDPlus HR Unique identifier of a NHDFlowline feature. Found in NHDPlus HR Only. Double true This field only exists when NHD feature classes are brought into NHDPlus HR.
OBJECTID Internal feature or event number. OBJECTID false
Permanent_Identifier A 40-character globally unique ID (GUID) value that uniquely identifies the occurrence of each feature or event in The National Map. Text false 40
ReachCode Unique identifier. The first eight digits are the WBD_HUC8. The next six digits are randomly assigned, sequential numbers that are unique within a HUC8. Text true 14 Required for all NHDFlowlines. NHDWaterbody and NHDPoint feature classes allow reach codes, but do not require them.
Resolution Source resolution. Long Integer false 0 Resolution Currently NHD is available as separate resolutions. Domain values: Local > 1:12,000 High 1:24,000/12,000 Medium 1:100,000
Shape Feature geometry. Geometry true
Shape_Area Area of feature in map units squared. Double true 0
Shape_Length Length of the feature, which may differ from the field measured length due to differences in calculation. Units are map units. Double true 0 All features should have a positive integer value.
VPUID Vector Processing Unit Identifier. Found in NHDPlus HR only. Text true 8 This field only exists when NHD feature classes are brought into NHDPlus HR.
VisibilityFilter Allows for filtering of features for usage of vector data at approximate scales. Long Integer false VisibilityFilter 0

SubTypes of NHDWaterbody

SubTypeDescriptionDefinition
361PlayaFlat area at the lowest part of an undrained desert basin, generally devoid of vegetation.
378Ice MassField of ice, formed in regions of perennial frost.
390LakePondStanding body of water with a predominantly natural shoreline surrounded by land.
436ReservoirConstructed basin formed to contain water or other liquids.
466SwampMarshNoncultivated, vegetated area that is inundated or saturated for a significant part of the year. The vegetation is adapted for life in saturated soil conditions.
493EstuaryLower end of a river, or a semi-enclosed coastal body of water with access to the open ocean, which is affected by the tides and where fresh and salt water mix.



NWIS Drainage Area: Drainage area as reported by NWIS.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
AgencyCode The code for the agency that reported the data to NWIS. Text true 5
AreaSqKm Area of feature in square kilometers based on Albers Equal Area projection. Double true 0 Computed.
ContributingAreaSqMi Drainage areas that contribute flow toward the outlet of a hydrologic unit, measured in square miles. Double true
GLOBALID An ID that is generated by the geodatabase when database versioning is enabled in ArcSDE. false
LoadDate LoadDate represents the date when the data were loaded into the official USGS WBD ArcSDE database. The field is the effective date for all feature edits, and it is automatically generated. Date false 0 22
MetaSourceID A unique identifier that links the element to the metadata tables. This ID is generated and assigned automatically by the database and remains with the object permanently. Text true 40
NWISContributingAreaSqMi Drainage areas that contribute flow toward the outlet of a hydrologic unit, measured in square miles - text field. Text true 10
NWISTotalAreaSqMi NWIS total drainage area for a site, measured in square miles - text field. Text true 10
ReferenceTNMIDNHDPointEvent Reference The National Map National Hydrography Dataset Point Event ID Text true 40
Shape Feature geometry. Geometry true
Shape_Area The size of the area in square decimal degrees. The values for this field are generated by ArcGIS. Primarily used in geodatabases. Double true 0
Shape_Length The perimeter of the area in decimal degrees or the length of the feature in decimal degrees. The values for this field are generated by ArcGIS. Primarily used in geodatabases. Double true 0
SiteNumber Unique 8- to 15-digit identification number for each site in the NWIS database. Text true 15
SourceDataDesc SourceDataDesc is a space provided for a brief description of the type of base data used to update or change the current WBD. The WBD In-State Steward completes this field as part of the metadata form. Text true 100
SourceFeatureID A long, unique code that identifies the parent of the feature if the feature is the result of a split or merge, and it is automatically generated and assigned. Text true 40
SourceOriginator SourceOriginator is the description of the agency that created the base data used to improve the WBD. The WBD In-State Steward completes this field as part of the metadata form. Text false 130
StationName Official station name for a site in NWIS. Text true 50
TNMID TNMID (short for The National Map Identification) is a unique 40-character field that identifies each element in the database exclusively. Text true 40
TotalAreaSqMi NWIS total drainage area for a site, measured in square miles. Double true
remarks Remarks for dataset. Text true 250




NWISDrainageLine: Drainage area boundary as reported by NWIS.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
AgencyCode The code for the agency that reported the data to NWIS. Text true 5
GLOBALID An ID that is generated by the geodatabase when database versioning is enabled in ArcSDE. false
LengthKM Length of linear feature. Value is computed when data are in Albers Equal Area projection. Double true 0 Computed
LineSource LineSource represents the code for the base data used for delineating hydrologic unit boundaries. Text true 75 Updated to 75 characters for WBD 2.3 schema.
LoadDate LoadDate represents the date when the data were loaded into the official USGS WBD ArcSDE database. The field is the effective date for all feature edits, and it is automatically generated. Date false 0 22
MetaSourceID A unique identifier that links the element to the metadata tables. This ID is generated and assigned automatically by the database and remains with the object permanently. Text true 40
Shape Feature geometry. Geometry true
Shape_Length The perimeter of the area in decimal degrees or the length of the feature in decimal degrees. The values for this field are generated by ArcGIS. Primarily used in geodatabases. Double true 0
SiteNumber Unique 8- to 15-digit identification number for each site in the NWIS database. Text true 15
SourceDataDesc SourceDataDesc is a space provided for a brief description of the type of base data used to update or change the current WBD. The WBD In-State Steward completes this field as part of the metadata form. Text true 100
SourceFeatureID A long, unique code that identifies the parent of the feature if the feature is the result of a split or merge, and it is automatically generated and assigned. Text true 40
SourceOriginator SourceOriginator is the description of the agency that created the base data used to improve the WBD. The WBD In-State Steward completes this field as part of the metadata form. Text false 130
TNMID TNMID (short for The National Map Identification) is a unique 40-character field that identifies each element in the database exclusively. Text true 40




NonContributingDrainageArea: Drainage areas that do not contribute flow toward the outlet of a hydrologic unit.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
AreaSqKm Area of feature in square kilometers based on Albers Equal Area projection. Double true 0 Computed.
GLOBALID An ID that is generated by the geodatabase when database versioning is enabled in ArcSDE. false
LoadDate LoadDate represents the date when the data were loaded into the official USGS WBD ArcSDE database. The field is the effective date for all feature edits, and it is automatically generated. Date false 0 22
MetaSourceID A unique identifier that links the element to the metadata tables. This ID is generated and assigned automatically by the database and remains with the object permanently. Text true 40
NonContributingAreaSqMi Drainage areas that do not contribute flow toward the outlet of a hydrologic unit, measured in square miles. Double true
Shape Feature geometry. Geometry true
Shape_Area The size of the area in square decimal degrees. The values for this field are generated by ArcGIS. Primarily used in geodatabases. Double true 0
Shape_Length The perimeter of the area in decimal degrees or the length of the feature in decimal degrees. The values for this field are generated by ArcGIS. Primarily used in geodatabases. Double true 0
SourceDataDesc SourceDataDesc is a space provided for a brief description of the type of base data used to update or change the current WBD. The WBD In-State Steward completes this field as part of the metadata form. Text true 100
SourceFeatureID A long, unique code that identifies the parent of the feature if the feature is the result of a split or merge, and it is automatically generated and assigned. Text true 40
SourceOriginator SourceOriginator is the description of the agency that created the base data used to improve the WBD. The WBD In-State Steward completes this field as part of the metadata form. Text false 130
TNMID TNMID (short for The National Map Identification) is a unique 40-character field that identifies each element in the database exclusively. Text true 40
remarks Remarks for dataset. Text true 250




NonContributingDrainageLine: Drainage lines that do not contribute flow toward the outlet of a hydrologic unit.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
GLOBALID An ID that is generated by the geodatabase when database versioning is enabled in ArcSDE. false
LengthKM Length of linear feature. Value is computed when data are in Albers Equal Area projection. Double true 0 Computed
LineSource The code for the base data used for delineating hydrologic unit boundaries. Text true 30
LoadDate LoadDate represents the date when the data were loaded into the official USGS WBD ArcSDE database. The field is the effective date for all feature edits, and it is automatically generated. Date false 0 22
MetaSourceID A unique identifier that links the element to the metadata tables. This ID is generated and assigned automatically by the database and remains with the object permanently. Text true 40
Shape Feature geometry. Geometry true
Shape_Length The perimeter of the area in decimal degrees or the length of the feature in decimal degrees. The values for this field are generated by ArcGIS. Primarily used in geodatabases. Double true 0
SourceDataDesc SourceDataDesc is a space provided for a brief description of the type of base data used to update or change the current WBD. The WBD In-State Steward completes this field as part of the metadata form. Text true 100
SourceFeatureID A long, unique code that identifies the parent of the feature if the feature is the result of a split or merge, and it is automatically generated and assigned. Text true 40
SourceOriginator SourceOriginator is the description of the agency that created the base data used to improve the WBD. The WBD In-State Steward completes this field as part of the metadata form. Text false 130
TNMID TNMID (short for The National Map Identification) is a unique 40-character field that identifies each element in the database exclusively. Text true 40




WBDHU10: A comprehensive aggregated collection of hydrologic unit data consistent with the national criteria for delineation and resolution. The WBD defines the perimeters of drainage areas (hydrologic units), formed by the terrain and other landscape charactersitcs, at a 1:24,000 scale in the United States, except for Alaska at 1:63,360 scale and 1:25,000 scale in the Caribbean, and it consists of digital geographic data that include six levels of detailed nested hydrologic unit boundaries. WBDHU10 represents the 10-digit hydrologic unit boundaries (previously referred to as Watersheds). Only the attribution is editable at the 10-digit hydrologic unit by the WBD In-State Steward. Within the United States, approximately 18,075 10-digit hydrologic units (Watersheds) are in the WBD.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
AreaAcres AreaAcres is common to all polygon feature classes and is calculated at the hydrologic unit from the intrinsic area value maintained by the GIS software; therefore, acreage values may vary from user calculations, depending on the projection of the data. North American Albers Equal Area Conic, North American Datum 1983 is the required projection to use for calculation. Double true
AreaSqKm AreaSqKm is calculated at the hydrologic unit from the intrinsic area value maintained by the GIS software; therefore, the square kilometer values may vary from user calculations, depending on the projection of the data. North American Albers Equal Area Conic, North American Datum 1983 is the default projection. Double true
HUC10 The HUC10 field is a unique 10-digit hydrologic unit code. Text true 10 This value is used in WBD and NHDPlus HR datasets. For NHDPlus HR, the hydrologic unit is used as a reference during NHDPlus HR data production.
HUMod The 10-digit hydrologic unit modification attribute is a two-character, uppercase abbreviation(s) for either (1) the type of modification to natural overland flow that alters the natural delineation of a 10-digit hydrologic unit or (2) the special conditions GF-groundwater flow, GL-glacier, IF-ice field, KA-karst, and NC-noncontributing area. Text true 30 For HU polygons
HUType The 10-digit hydrologic unit type attribute is the single-letter abbreviation for Watershed type from the list of official names. Text true 1 HUType Domain Has domain. Updated to 1 character for WBD 2.3 schema.
LoadDate LoadDate represents the date when the data were loaded into the official USGS WBD ArcSDE database. The field is the effective date for all feature edits, and it is automatically generated. Date false 0 22
MetaSourceID A unique identifier that links the element to the metadata tables. This ID is generated and assigned automatically by the database and remains with the object permanently. Text true 40
Name Watershed name refers to the GNIS name for the geographic area in which the hydrologic unit is located. Text true 120
ReferenceGNIS_IDs Comma delimited list of up to three GNIS_ID's identifying the hydrologic, geologic, or geographic features for which the Hydrologic Unit is named. Text true 50 New attribute for WBD 2.3 schema.
SourceDataDesc SourceDataDesc is a space provided for a brief description of the type of base data used to update or change the current WBD. The WBD In-State Steward completes this field as part of the metadata form. Text true 100
SourceFeatureID A long, unique code that identifies the parent of the feature if the feature is the result of a split or merge, and it is automatically generated and assigned. Text true 40
SourceOriginator SourceOriginator is the description of the agency that created the base data used to improve the WBD. The WBD In-State Steward completes this field as part of the metadata form. Text false 130
States The States or outlying area attribute identifies the State(s) or outlying areas that the hydrologic unit falls within or touches. The U.S. Census Bureau 1:100,000-scale State layer will be used to establish State boundaries in the derivation process. Text true 50 For WBD, indicates the states that contribute drainage to a hydrologic unit area.
TNMID TNMID (short for The National Map Identification) is a unique 40-character field that identifies each element in the database exclusively. Text true 40




WBDHU12: A comprehensive aggregated collection of hydrologic unit data consistent with the national criteria for delineation and resolution. The WBD defines the perimeters of drainage areas (hydrologic units), formed by the terrain and other landscape charactersitcs, at a 1:24,000 scale in the United States, except for Alaska at 1:63,360 scale and 1:25,000 scale in the Caribbean, and it consists of digital geographic data that include six levels of detailed nested hydrologic unit boundaries. WBDHU12 represents the 12-digit hydrologic unit boundaries (previously referred to as Subwatersheds). Within the United States, approximately 98,363 12-digit hydrologic units are in the WBD.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
AreaAcres AreaAcres is common to all polygon feature classes and is calculated at the hydrologic unit from the intrinsic area value maintained by the GIS software; therefore, acreage values may vary from user calculations, depending on the projection of the data. North American Albers Equal Area Conic, North American Datum 1983 is the required projection to use for calculation. Double true
AreaSqKm AreaSqKm is calculated at the hydrologic unit from the intrinsic area value maintained by the GIS software; therefore, the square kilometer values may vary from user calculations, depending on the projection of the data. North American Albers Equal Area Conic, North American Datum 1983 is the default projection. Double true
HUC12 The HUC12 field is a unique 12-digit hydrologic unit code. Text true 0 12 This value is used in WBD and NHDPlus HR datasets. For NHDPlus HR, the hydrologic unit is used as a reference during NHDPlus HR data production.
HUMod The 10-digit hydrologic unit modification attribute is a two-character, uppercase abbreviation(s) for either (1) the type of modification to natural overland flow that alters the natural delineation of a 10-digit hydrologic unit or (2) the special conditions GF-groundwater flow, GL-glacier, IF-ice field, KA-karst, and NC-noncontributing area. Text true 30 For HU polygons
HUType The 12-digit hydrologic unit type attribute is the single-letter abbreviation for Subwatershed type from the list of official names. Text false 999 1 Has domain
LoadDate LoadDate represents the date when the data were loaded into the official USGS WBD ArcSDE database. The field is the effective date for all feature edits, and it is automatically generated. Date false 0 22
MetaSourceID A unique identifier that links the element to the metadata tables. This ID is generated and assigned automatically by the database and remains with the object permanently. Text true 40
NHDPlusID NHDPlus HR Unique identifier of a NHDFlowline feature. Found in NHDPlus HR Only. Double true This field only exists when NHD feature classes are brought into NHDPlus HR.
Name Subwatershed name refers to the GNIS name for the geographic area in which the hydrologic unit is located. Text true 120
NonContributingAreaAcres Drainage area (acres) that does not contribute flow toward the outlet of a hydrologic unit. New in WBD 2.3 schema. Double true 0
NonContributingAreaSqKm Drainage area (SqKM) that does not contribute flow toward the outlet of a hydrologic unit. Double true 0
ReferenceGNIS_IDs Comma delimited list of up to three GNIS_ID's identifying the hydrologic, geologic, or geographic features for which the Hydrologic Unit is named. Text true 50 New attribute for WBD 2.3 schema.
Shape_Area Area of feature in map units squared. Double true 0
Shape_Length Length of the feature, which may differ from the field measured length due to differences in calculation. Units are map units. Double true 0 All features should have a positive integer value.
SourceDataDesc SourceDataDesc is a space provided for a brief description of the type of base data used to update or change the current WBD. The WBD In-State Steward completes this field as part of the metadata form. Text true 100
SourceFeatureID A long, unique code that identifies the parent of the feature if the feature is the result of a split or merge, and it is automatically generated and assigned. Text true 40
SourceOriginator SourceOriginator is the description of the agency that created the base data used to improve the WBD. The WBD In-State Steward completes this field as part of the metadata form. Text false 130
States The States or outlying area attribute identifies the State(s) or outlying areas that the hydrologic unit falls within or touches. The U.S. Census Bureau 1:100,000-scale State layer will be used to establish State boundaries in the derivation process. Text true 50 For WBD, indicates the states that contribute drainage to a hydrologic unit area.
TNMID TNMID (short for The National Map Identification) is a unique 40-character field that identifies each element in the database exclusively. Text true 40
ToHUC The 12-digit hydrologic unit ToHUC code attribute is the code for the 12-digit hydrologic unit that is downstream from and naturally receives the majority of the flow from another 12-digit hydrologic unit. Text true 16
VPUID Vector Processing Unit Identifier. Found in NHDPlus HR only. Text true 8 This field only exists when NHD feature classes are brought into NHDPlus HR.




WBDHU14: A comprehensive aggregated collection of hydrologic unit data consistent with the national criteria for delineation and resolution. The WBD defines the perimeters of drainage areas (hydrologic units), formed by the terrain and other landscape charactersitcs, at a 1:24,000 scale in the United States, except for Alaska at 1:63,360 scale and 1:25,000 scale in the Caribbean, and it consists of digital geographic data that include six levels of detailed nested hydrologic unit boundaries. WBDHU14 represents the 14-digit hydrologic unit boundaries. This hydrologic unit lacks a common name. WBDHU14 is a new subdivision in the WBD. Subdivisions at the 14-digit hydrologic unit are not required, but these smaller units are being created to support specific project work at the local level. If they are created in accordance with this standard, they will be included in the WBD.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
AreaAcres AreaAcres is common to all polygon feature classes and is calculated at the hydrologic unit from the intrinsic area value maintained by the GIS software; therefore, acreage values may vary from user calculations, depending on the projection of the data. North American Albers Equal Area Conic, North American Datum 1983 is the required projection to use for calculation. Double true
AreaSqKm AreaSqKm is calculated at the hydrologic unit from the intrinsic area value maintained by the GIS software; therefore, the square kilometer values may vary from user calculations, depending on the projection of the data. North American Albers Equal Area Conic, North American Datum 1983 is the default projection. Double true
GNIS_ID GNIS_ID is a preassigned numeric field that uses a unique number to relate the name of the hydrologic unit to the GNIS names database. This field is automatically generated in the database. Long Integer false
HUC14 The HUC14 field is a unique 14-digit hydrologic unit code. Text true 14 This value is used in WBD and NHDPlus HR datasets. For NHDPlus HR, the hydrologic unit is used as a reference during NHDPlus HR data production.
HUMod The 10-digit hydrologic unit modification attribute is a two-character, uppercase abbreviation(s) for either (1) the type of modification to natural overland flow that alters the natural delineation of a 10-digit hydrologic unit or (2) the special conditions GF-groundwater flow, GL-glacier, IF-ice field, KA-karst, and NC-noncontributing area. Text true 30 For HU polygons
HUType The 14-digit hydrologic unit type attribute is the single-letter abbreviation for Subwatershed type from the list of official names. Text false 999 1 Has domain
LoadDate LoadDate represents the date when the data were loaded into the official USGS WBD ArcSDE database. The field is the effective date for all feature edits, and it is automatically generated. Date false 0 22
MetaSourceID A unique identifier that links the element to the metadata tables. This ID is generated and assigned automatically by the database and remains with the object permanently. Text true 40
Name The 14-digit hydrologic unit name refers to the GNIS name for the geographic area in which the hydrologic unit is located. Text true 120
NonContributingAreaSqKm Drainage area (SqKM) that does not contribute flow toward the outlet of a hydrologic unit. Double true 0
ReferenceGNIS_IDs Comma delimited list of up to three GNIS_ID's identifying the hydrologic, geologic, or geographic features for which the Hydrologic Unit is named. Text true 50 New attribute for WBD 2.3 schema.
Shape_Area Area of feature in map units squared. Double true 0
Shape_Length Length of the feature, which may differ from the field measured length due to differences in calculation. Units are map units. Double true 0 All features should have a positive integer value.
SourceDataDesc SourceDataDesc is a space provided for a brief description of the type of base data used to update or change the current WBD. The WBD In-State Steward completes this field as part of the metadata form. Text true 100
SourceFeatureID A long, unique code that identifies the parent of the feature if the feature is the result of a split or merge, and it is automatically generated and assigned. Text true 40
SourceOriginator SourceOriginator is the description of the agency that created the base data used to improve the WBD. The WBD In-State Steward completes this field as part of the metadata form. Text false 130
States The States or outlying area attribute identifies the State(s) or outlying areas that the hydrologic unit falls within or touches. The U.S. Census Bureau 1:100,000-scale State layer will be used to establish State boundaries in the derivation process. Text true 50 For WBD, indicates the states that contribute drainage to a hydrologic unit area.
TNMID TNMID (short for The National Map Identification) is a unique 40-character field that identifies each element in the database exclusively. Text true 40
ToHUC The 14-digit hydrologic unit ToHUC code attribute is the code for the 14-digit hydrologic unit that is downstream from and naturally receives the majority of the flow from another 14-digit hydrologic unit. Text true 16 Has domain. Added to WBDHU14 for WBD 2.3 schema.




WBDHU16: A comprehensive aggregated collection of hydrologic unit data consistent with the national criteria for delineation and resolution. The WBD defines the perimeters of drainage areas (hydrologic units), formed by the terrain and other landscape charactersitcs, at a 1:24,000 scale in the United States, except for Alaska at 1:63,360 scale and 1:25,000 scale in the Caribbean, and it consists of digital geographic data that include six levels of detailed nested hydrologic unit boundaries. WBDHU16 represents the 16-digit hydrologic unit boundaries. This hydrologic unit lacks a common name. This is a new subdivision in the WBD. Subdivisions at the 16-digit hydrologic unit are not required, but these smaller units are being created to support specific project work at the local level. If they are created in accordance with this standard, they will be included in the WBD.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
AreaAcres AreaAcres is common to all polygon feature classes and is calculated at the hydrologic unit from the intrinsic area value maintained by the GIS software; therefore, acreage values may vary from user calculations, depending on the projection of the data. North American Albers Equal Area Conic, North American Datum 1983 is the required projection to use for calculation. Double true
AreaSqKm AreaSqKm is calculated at the hydrologic unit from the intrinsic area value maintained by the GIS software; therefore, the square kilometer values may vary from user calculations, depending on the projection of the data. North American Albers Equal Area Conic, North American Datum 1983 is the default projection. Double true
GNIS_ID A permanent, unique number assigned by the Geographic Names Information System (GNIS) to a geographic feature name for the sole purpose of uniquely identifying that name application as a record in any information system database, dataset, file, or document Text true 10 GNIS_ID = "null" if no name is associated with the feature. Removed from WBD as of version 2.3 schema.
HUC16 The HUC16 field is a unique 16-digit hydrologic unit code. Text true 16 This value is used in WBD and NHDPlus HR datasets. For NHDPlus HR, the hydrologic unit is used as a reference during NHDPlus HR data production.
HUMod The 10-digit hydrologic unit modification attribute is a two-character, uppercase abbreviation(s) for either (1) the type of modification to natural overland flow that alters the natural delineation of a 10-digit hydrologic unit or (2) the special conditions GF-groundwater flow, GL-glacier, IF-ice field, KA-karst, and NC-noncontributing area. Text true 30 For HU polygons
HUType The 16-digit hydrologic unit type attribute is the single-letter abbreviation for Subwatershed type from the list of official names. Text false 999 1 Has domain
LoadDate LoadDate represents the date when the data were loaded into the official USGS WBD ArcSDE database. The field is the effective date for all feature edits, and it is automatically generated. Date false 0 22
MetaSourceID A unique identifier that links the element to the metadata tables. This ID is generated and assigned automatically by the database and remains with the object permanently. Text true 40
Name The 16-digit hydrologic unit name refers to the GNIS name for the geographic area in which the hydrologic unit is located. Text false 999 120
NonContributingAreaSqKm Drainage area (SqKM) that does not contribute flow toward the outlet of a hydrologic unit. Double true 0
ReferenceGNIS_IDs Comma delimited list of up to three GNIS_ID's identifying the hydrologic, geologic, or geographic features for which the Hydrologic Unit is named. Text true 50 New attribute for WBD 2.3 schema.
Shape_Area Area of feature in map units squared. Double true 0
Shape_Length Length of the feature, which may differ from the field measured length due to differences in calculation. Units are map units. Double true 0 All features should have a positive integer value.
SourceDataDesc SourceDataDesc is a space provided for a brief description of the type of base data used to update or change the current WBD. The WBD In-State Steward completes this field as part of the metadata form. Text true 100
SourceFeatureID A long, unique code that identifies the parent of the feature if the feature is the result of a split or merge, and it is automatically generated and assigned. Text true 40
SourceOriginator SourceOriginator is the description of the agency that created the base data used to improve the WBD. The WBD In-State Steward completes this field as part of the metadata form. Text false 130
States The States or outlying area attribute identifies the State(s) or outlying areas that the hydrologic unit falls within or touches. The U.S. Census Bureau 1:100,000-scale State layer will be used to establish State boundaries in the derivation process. Text true 50 For WBD, indicates the states that contribute drainage to a hydrologic unit area.
TNMID TNMID (short for The National Map Identification) is a unique 40-character field that identifies each element in the database exclusively. Text true 40
ToHUC The 16-digit hydrologic unit ToHUC code attribute is the code for the 16-digit hydrologic unit that is downstream from and naturally receives the majority of the flow from another 16-digit hydrologic unit. Text true 16 Has domain. Added to WBDHU14 for WBD 2.3 schema.




WBDHU2: A comprehensive aggregated collection of hydrologic unit data consistent with the national criteria for delineation and resolution. The WBD defines the perimeters of drainage areas (hydrologic units), formed by the terrain and other landscape charactersitcs, at a 1:24,000 scale in the United States, except for Alaska at 1:63,360 scale and 1:25,000 scale in the Caribbean, and it consists of digital geographic data that include six levels of detailed nested hydrologic unit boundaries. WBDHU2 represents the 2-digit hydrologic unit boundaries (previously referred to as Regions) and are part of the WBD delivery, but these boundaries are not editable by the WBD In-State Steward. There are 22 2-digit hydrologic units (Regions) in the WBD

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
AreaAcres AreaAcres is common to all polygon feature classes and is calculated at the hydrologic unit from the intrinsic area value maintained by the GIS software; therefore, acreage values may vary from user calculations, depending on the projection of the data. North American Albers Equal Area Conic, North American Datum 1983 is the required projection to use for calculation. Double true
AreaSqKm AreaSqKm is calculated at the hydrologic unit from the intrinsic area value maintained by the GIS software; therefore, the square kilometer values may vary from user calculations, depending on the projection of the data. North American Albers Equal Area Conic, North American Datum 1983 is the default projection. Double true
GNIS_ID A permanent, unique number assigned by the Geographic Names Information System (GNIS) to a geographic feature name for the sole purpose of uniquely identifying that name application as a record in any information system database, dataset, file, or document Text true 10 GNIS_ID = "null" if no name is associated with the feature. Removed from WBD as of version 2.3 schema.
HUC2 The HUC2 field is a unique 2-digit hydrologic unit code. Text true 2 This value is used in WBD and NHDPlus HR datasets. For NHDPlus HR, the hydrologic unit is used as a reference during NHDPlus HR data production.
LoadDate LoadDate represents the date when the data were loaded into the official USGS WBD ArcSDE database. The field is the effective date for all feature edits, and it is automatically generated. Date false 0 22
MetaSourceID A unique identifier that links the element to the metadata tables. This ID is generated and assigned automatically by the database and remains with the object permanently. Text true 40
Name Name refers to the GNIS name for the geographic area in which the hydrologic unit is located. Text false 999 120
ReferenceGNIS_IDs Comma delimited list of up to three GNIS_ID's identifying the hydrologic, geologic, or geographic features for which the Hydrologic Unit is named. Text true 50 New attribute for WBD 2.3 schema.
Shape_Area Area of feature in map units squared. Double true 0
Shape_Length Length of the feature, which may differ from the field measured length due to differences in calculation. Units are map units. Double true 0 All features should have a positive integer value.
SourceDataDesc SourceDataDesc is a space provided for a brief description of the type of base data used to update or change the current WBD. The WBD In-State Steward completes this field as part of the metadata form. Text true 100
SourceFeatureID A long, unique code that identifies the parent of the feature if the feature is the result of a split or merge, and it is automatically generated and assigned. Text true 40
SourceOriginator SourceOriginator is the description of the agency that created the base data used to improve the WBD. The WBD In-State Steward completes this field as part of the metadata form. Text false 130
States The States or outlying area attribute identifies the State(s) or outlying areas that the hydrologic unit falls within or touches. The U.S. Census Bureau 1:100,000-scale State layer will be used to establish State boundaries in the derivation process. Text true 50 For WBD, indicates the states that contribute drainage to a hydrologic unit area.
TNMID TNMID (short for The National Map Identification) is a unique 40-character field that identifies each element in the database exclusively. Text true 40




WBDHU4: A comprehensive aggregated collection of hydrologic unit data consistent with the national criteria for delineation and resolution. The WBD defines the perimeters of drainage areas (hydrologic units), formed by the terrain and other landscape charactersitcs, at a 1:24,000 scale in the United States, except for Alaska at 1:63,360 scale and 1:25,000 scale in the Caribbean, and it consists of digital geographic data that include six levels of detailed nested hydrologic unit boundaries. WBDHU4 represents the 4-digit hydrologic unit boundaries (previously referred to as Subregions) that are part of the WBD delivery, but the boundaries are not editable by the WBD In-State Steward. There are 222 4-digit hydrologic units (Subregions) in the WBD.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
AreaAcres AreaAcres is common to all polygon feature classes and is calculated at the hydrologic unit from the intrinsic area value maintained by the GIS software; therefore, acreage values may vary from user calculations, depending on the projection of the data. North American Albers Equal Area Conic, North American Datum 1983 is the required projection to use for calculation. Double true
AreaSqKm AreaSqKm is calculated at the hydrologic unit from the intrinsic area value maintained by the GIS software; therefore, the square kilometer values may vary from user calculations, depending on the projection of the data. North American Albers Equal Area Conic, North American Datum 1983 is the default projection. Double true
GNIS_ID GNIS_ID is a preassigned numeric field that uses a unique number to relate the name of the hydrologic unit to the GNIS names database. This field is automatically generated in the database. Long Integer false
HUC4 The HUC4 field is a unique 4-digit hydrologic unit code. Text true 4 This value is used in WBD and NHDPlus HR datasets. For NHDPlus HR, the hydrologic unit is used as a reference during NHDPlus HR data production.
LoadDate LoadDate represents the date when the data were loaded into the official USGS WBD ArcSDE database. The field is the effective date for all feature edits, and it is automatically generated. Date false 0 22
MetaSourceID A unique identifier that links the element to the metadata tables. This ID is generated and assigned automatically by the database and remains with the object permanently. Text true 40
Name Subregion name refers to the GNIS name for the geographic area in which the hydrologic unit is located. Text false 999 120
ReferenceGNIS_IDs Comma delimited list of up to three GNIS_ID's identifying the hydrologic, geologic, or geographic features for which the Hydrologic Unit is named. Text true 50 New attribute for WBD 2.3 schema.
Shape_Area Area of feature in map units squared. Double true 0
Shape_Length Length of the feature, which may differ from the field measured length due to differences in calculation. Units are map units. Double true 0 All features should have a positive integer value.
SourceDataDesc SourceDataDesc is a space provided for a brief description of the type of base data used to update or change the current WBD. The WBD In-State Steward completes this field as part of the metadata form. Text true 100
SourceFeatureID A long, unique code that identifies the parent of the feature if the feature is the result of a split or merge, and it is automatically generated and assigned. Text true 40
SourceOriginator SourceOriginator is the description of the agency that created the base data used to improve the WBD. The WBD In-State Steward completes this field as part of the metadata form. Text false 130
States The States or outlying area attribute identifies the State(s) or outlying areas that the hydrologic unit falls within or touches. The U.S. Census Bureau 1:100,000-scale State layer will be used to establish State boundaries in the derivation process. Text true 50 For WBD, indicates the states that contribute drainage to a hydrologic unit area.
TNMID TNMID (short for The National Map Identification) is a unique 40-character field that identifies each element in the database exclusively. Text true 40




WBDHU6: A comprehensive aggregated collection of hydrologic unit data consistent with the national criteria for delineation and resolution. The WBD defines the perimeters of drainage areas (hydrologic units), formed by the terrain and other landscape charactersitcs, at a 1:24,000 scale in the United States, except for Alaska at 1:63,360 scale and 1:25,000 scale in the Caribbean, and it consists of digital geographic data that include six levels of detailed nested hydrologic unit boundaries. WBDHU6 represents the 6-digit hydrologic unit boundaries (previously referred to as Basins) and are part of the WBD delivery, but the boundaries are not editable by the WBD In-State Steward. Approximately 386 6-digit hydrologic units (Basins) are in the WBD.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
AreaAcres AreaAcres is common to all polygon feature classes and is calculated at the hydrologic unit from the intrinsic area value maintained by the GIS software; therefore, acreage values may vary from user calculations, depending on the projection of the data. North American Albers Equal Area Conic, North American Datum 1983 is the required projection to use for calculation. Double true
AreaSqKm AreaSqKm is calculated at the hydrologic unit from the intrinsic area value maintained by the GIS software; therefore, the square kilometer values may vary from user calculations, depending on the projection of the data. North American Albers Equal Area Conic, North American Datum 1983 is the default projection. Double true
HUC6 The HUC6 field is a unique 6-digit hydrologic unit code. Text true 6 This value is used in WBD and NHDPlus HR datasets. For NHDPlus HR, the hydrologic unit is used as a reference during NHDPlus HR data production.
LoadDate LoadDate represents the date when the data were loaded into the official USGS WBD ArcSDE database. The field is the effective date for all feature edits, and it is automatically generated. Date false 0 22
MetaSourceID A unique identifier that links the element to the metadata tables. This ID is generated and assigned automatically by the database and remains with the object permanently. Text true 40
Name Basin name refers to the GNIS name for the geographic area in which the hydrologic unit is located. Text false 999 120
ReferenceGNIS_IDs Comma delimited list of up to three GNIS_ID's identifying the hydrologic, geologic, or geographic features for which the Hydrologic Unit is named. Text true 50 New attribute for WBD 2.3 schema.
Shape_Area Area of feature in map units squared. Double true 0
Shape_Length Length of the feature, which may differ from the field measured length due to differences in calculation. Units are map units. Double true 0 All features should have a positive integer value.
SourceDataDesc SourceDataDesc is a space provided for a brief description of the type of base data used to update or change the current WBD. The WBD In-State Steward completes this field as part of the metadata form. Text true 100
SourceFeatureID A long, unique code that identifies the parent of the feature if the feature is the result of a split or merge, and it is automatically generated and assigned. Text true 40
SourceOriginator SourceOriginator is the description of the agency that created the base data used to improve the WBD. The WBD In-State Steward completes this field as part of the metadata form. Text false 130
States The States or outlying area attribute identifies the State(s) or outlying areas that the hydrologic unit falls within or touches. The U.S. Census Bureau 1:100,000-scale State layer will be used to establish State boundaries in the derivation process. Text true 50 For WBD, indicates the states that contribute drainage to a hydrologic unit area.
TNMID TNMID (short for The National Map Identification) is a unique 40-character field that identifies each element in the database exclusively. Text true 40




WBDHU8: A comprehensive aggregated collection of hydrologic unit data consistent with the national criteria for delineation and resolution. The WBD defines the perimeters of drainage areas (hydrologic units), formed by the terrain and other landscape charactersitcs, at a 1:24,000 scale in the United States, except for Alaska at 1:63,360 scale and 1:25,000 scale in the Caribbean, and it consists of digital geographic data that include six levels of detailed nested hydrologic unit boundaries. WBDHU8 represents the 8-digit hydrologic unit boundaries (previously referred to as Subbasins) and are part of the WBD delivery, but the boundaries are not editable by the WBD In-State Steward. Approximately 2,297 8-digit hydrologic units (Subbasins) are in the WBD.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
AreaAcres AreaAcres is common to all polygon feature classes and is calculated at the hydrologic unit from the intrinsic area value maintained by the GIS software; therefore, acreage values may vary from user calculations, depending on the projection of the data. North American Albers Equal Area Conic, North American Datum 1983 is the required projection to use for calculation. Double true
AreaSqKm AreaSqKm is calculated at the hydrologic unit from the intrinsic area value maintained by the GIS software; therefore, the square kilometer values may vary from user calculations, depending on the projection of the data. North American Albers Equal Area Conic, North American Datum 1983 is the default projection. Double true
GNIS_ID GNIS_ID is a preassigned numeric field that uses a unique number to relate the name of the hydrologic unit to the GNIS names database. This field is automatically generated in the database. Long Integer false
HUC8 The HUC8 field is a unique 8-digit hydrologic unit code. Text true 8 This value is used in WBD and NHDPlus HR datasets. For NHDPlus HR, the hydrologic unit is used as a reference during NHDPlus HR data production.
LoadDate LoadDate represents the date when the data were loaded into the official USGS WBD ArcSDE database. The field is the effective date for all feature edits, and it is automatically generated. Date false 0 22
MetaSourceID A unique identifier that links the element to the metadata tables. This ID is generated and assigned automatically by the database and remains with the object permanently. Text true 40
Name Subbasin name refers to the GNIS name for the geographic area in which the hydrologic unit is located. Text false 999 120
ReferenceGNIS_IDs Comma delimited list of up to three GNIS_ID's identifying the hydrologic, geologic, or geographic features for which the Hydrologic Unit is named. Text true 50 New attribute for WBD 2.3 schema.
Shape_Area Area of feature in map units squared. Double true 0
Shape_Length Length of the feature, which may differ from the field measured length due to differences in calculation. Units are map units. Double true 0 All features should have a positive integer value.
Shape_Length Length of the feature, which may differ from the field measured length due to differences in calculation. Units are map units. Double true 0 All features should have a positive integer value.
SourceDataDesc SourceDataDesc is a space provided for a brief description of the type of base data used to update or change the current WBD. The WBD In-State Steward completes this field as part of the metadata form. Text true 100
SourceFeatureID A long, unique code that identifies the parent of the feature if the feature is the result of a split or merge, and it is automatically generated and assigned. Text true 40
SourceOriginator SourceOriginator is the description of the agency that created the base data used to improve the WBD. The WBD In-State Steward completes this field as part of the metadata form. Text false 130
States The States or outlying area attribute identifies the State(s) or outlying areas that the hydrologic unit falls within or touches. The U.S. Census Bureau 1:100,000-scale State layer will be used to establish State boundaries in the derivation process. Text true 50 For WBD, indicates the states that contribute drainage to a hydrologic unit area.
TNMID TNMID (short for The National Map Identification) is a unique 40-character field that identifies each element in the database exclusively. Text true 40




WBDLine: Hydrologic unit boundaries are delineated and digitized as lines. The digital lines are processed by using GIS software to form polygons.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
HUDigit HUDigit is a domain-based field that indicates the minimum number of digits used to represent the hydrologic unit bounded by the line. Long Integer true 24 This is for the line feature class, has domain
HUMod The HUMod line modification attribute, completed by the WBD In-State Steward, is the two-character, uppercase abbreviation(s) code used to track either the modification to natural overland flow that alters the location of the hydrologic unit boundary or special conditions that are applied to a specific boundary line segment. The value identifies the type of modification, from the list provided, that has been applied to the boundary segment. Text false 999 20 This is for the line feature class
LineSource LineSource represents the code for the base data used for delineating hydrologic unit boundaries. Text true 75 Updated to 75 characters for WBD 2.3 schema.
LoadDate LoadDate represents the date when the data were loaded into the official USGS WBD ArcSDE database. The field is the effective date for all feature edits, and it is automatically generated. Date false 0 22
MetaSourceID A unique identifier that links the element to the metadata tables. This ID is generated and assigned automatically by the database and remains with the object permanently. Text true 40
NHDPlusID NHDPlus HR Unique identifier of a NHDFlowline feature. Found in NHDPlus HR Only. Double true This field only exists when NHD feature classes are brought into NHDPlus HR.
NHDPlusID NHDPlus HR Unique identifier of a NHDFlowline feature. Found in NHDPlus HR Only. Double true This field only exists when NHD feature classes are brought into NHDPlus HR.
Shape Feature geometry. Geometry true
Shape_Length Length of the feature, which may differ from the field measured length due to differences in calculation. Units are map units. Double true 0 All features should have a positive integer value.
TNMID TNMID (short for The National Map Identification) is a unique 40-character field that identifies each element in the database exclusively. Text true 40
VPUID Vector Processing Unit Identifier. Found in NHDPlus HR only. Text true 8 This field only exists when NHD feature classes are brought into NHDPlus HR.





NON-SPATIAL TABLES

ExternalCrosswalk : Contains associations of Permanent_Identifiers to external source Identifiers.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
ExternalID ID that identifies the feature in the source dataset. Text true 40
ExternalIDEntryDate Load date of the ExternalID record. Date true
ExternalIDName Field name in the external source dataset that contains the unique IDs. Text true 50
ExternalIDOriginator Name of the organization or individual who developed the external dataset/features. Text true 130
OBJECTID Internal feature or event number. OBJECTID false
OrganizationType Administrative level code of the organization or individual who developed the external dataset/features. Long Integer true 0
Permanent_Identifier A 40-character globally unique ID (GUID) value that uniquely identifies the occurrence of each feature or event in The National Map. Text false 40

FeatureToMetadata : Table that links the features / objects to one or more processes and their sources. This table gives the model the capability of lineage or the capability of tracking the history of changes for a given feature.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
MetaProcessID Unique ID for a metadata process description. Text false 40 Features are associated to specific process descriptions. The Meta_ProcessID links to the NHDMetadata table.
OBJECTID Internal feature or event number. OBJECTID false
TNMID TNMID (short for The National Map Identification) is a unique 40-character field that identifies each element in the database exclusively. Text true 40

MetaProcessDetail : Table with information specific to the processor (contact information) and the process used in loading or updating the dataset features or objects.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
Address Address line for the address. Text true 100
City City of the address. Text true 40
ContactEmailAddress E-mail address to reach contact organization or individual. Text true 40
ContactInstructions Supplemental instructions to contact Organization or individual. Text true 120
ContactOrganization Name or organization to which type of contact applies. Text true 100
ContactURL The address of a resource on the internet (i.e., a website address) for the contact organization or individual that is associated with loading or updating the data. Text true 100
ContactVoiceTelephone Telephone number to reach Organization or individual. Text true 40
DataSetCredit Recognition of those who contributed to the dataset. Text true 4000
EditType A description of the type of edit made. true 4 EditType Domain
LoadDate Date and time feature or event was loaded into the database. Timestamp indicating when the feature or event was last edited. true 8
MetaProcessID Unique ID for a metadata process description. Text false 40 Features are associated to specific process descriptions. The Meta_ProcessID links to the NHDMetadata table.
OBJECTID Internal feature or event number. OBJECTID false
PostalCode ZIP or other postal code of the address. Text true 20
ProcessDate Date when the event was completed. false 8
ProcessDescription Explanation of the event and related parameters or tolerances. Text false 4000
StateOrProvince State or province of the address. Text true 30

MetaSourceDetail : Information specific to the source of the data, including the citation, data quality and metadata information.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
AttributeAccuracyReport Explanation of entities and assignments of values in dataset. Text true 1800
BeginningDate First year of the event (if Range_of_Dates applies). Date true 8
CalendarDate The year (if Single Date applies). Date true 8
CompletenessReport Information about omissions, criteria, definitions used to derive dataset. Text true 2400
Edition The version of the title for the dataset (generally pertains to digital sources only). Text true 100
EndingDate Last year for the event (if Range_of_Dates applies). Date true 8
HorizPositionalAccuracyReport Horizontal coordinate measurements and description of tests used. Text true 3100
LogicalConsistencyReport Explanation of fidelity of relationships in dataset and tests used. Text true 1000
MetaSourceID A unique identifier that links the element to the metadata tables. This ID is generated and assigned automatically by the database and remains with the object permanently. Text true 40
MetadataDate Date the metadata was last created or updated. Date true 8
MetadataStandardName Name of the metadata standard used to document the dataset. Text true 100
MetadataStandardVersion Identification of the version of the metadata standard used to document the dataset. Text true 40
OBJECTID Internal feature or event number. OBJECTID false
PublicationDate Date the dataset is published or made available for release. Date true
SeriesIssue Information identifying the issue of the series publication of which the datset is a part (i.e. ). Text true 200
SeriesName The name of the series publication of which the data set is a part (i.e. USGS 1:24,000-scale topographic maps). Text true 200
SourceCitationAbbreviation Short form alias for source citation. Text true 255
SourceContribution Brief statement identifying the information contributed by the source to the datset. Text true 750
SourceCurrentnessReference The basis on which the source time period of content information of the source data set is determined. Text true 255
SourceIDFieldName The name of the attribute field that contains the globally unique and persistent identifier of an instance (for example: an instance of a feature or record) in the source data set. Note this is not the ObjectID, OID, FID fields which are auto-generated in ArcGIS. Text true 50
SourceOriginator The name of an organization or individual that developed the dataset. Text true 130
SourceRefType Long Integer true 5 SourceRefType Domain
SourceScaleDenominator Long Integer true 4
SourceURL The name of an online computer resource that contains the source of the dataset, for datasets with website or dataset (online) SourceRefTypes. Text true 100
Title The name by which the dataset is known (generally pertains to digital sources only). Text true 100
VertPositionalAccuracyReport Vertical coordinate measurements and description of tests used. Text true 3100

NHDFCode :

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
CanalDitchType Function or purpose of the feature (Aqueduct or Unspecified). Text true Values are Aqueduct or Unspecified.
ConstructionMaterial Predominant material used to construct the feature. Text true Values are Earthen, Nonearthen, or Unspecified.
Description Character string that contains all the characteristics and values associated with a feature code. Text false 255 Only some features have attributes; only feature type is used if no additional values are encoded.
FCode Feature Code. Numeric value that encodes a set of characteristics for a type of feature. This five-digit code has two parts: the first three digits encode the feature type (FType); the last two digits encode values for a unique set of characteristics associated with the feature type. The set of characteristics may be single valued or multi-valued. Long Integer true 0 default value varies, depending on feature
HydrographicCategory Portion of the year the feature contains water. Text true 32 Values are Intermittent, Ephemeral or Perennial.
InundationControlStatus Existence of functional control structures. Text true 32 Values are Controlled or Not Controlled.
OBJECTID Internal feature or event number. OBJECTID false
OperationalStatus State or condition of the feature. Text true 32 Values are Abandoned or Operational.
PipelineType Function or purpose of the feature. Text true 32 Values are Aqueduct, General, Penstock or Siphon.
PositionalAccuracy The accuracy within which a feature may be confidently positioned. Text true 32 Values are Approximate or Definite.
RelationshipToSurface Vertical location of the feature relative to the surface. Text true 32 Values are Abovewater or Underwater.
ReservoirType Function or purpose of the feature. Text true 32 Values are Aquaculture, Decorative Pool, Disposal, Evaporator, Swim Pool, Treatment, Unspecified or Water Storage.
Stage Height of the feature's water surface. Text true 32 Values are High Water Elevation, Date of Photography, Average Water Elevation, Normal Pool, Date of Photography, Spillway Elevation, Flood Elevation.

NHDFeatureToMetadata : Table linking every feature in the NHD to one or many metadata records.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
GLOBALID An ID that is generated by the geodatabase when database versioning is enabled in ArcSDE. false
Meta_ProcessID 40-char GUID value that uniquely identifies a metadata process description in The National Map. Text false 40 Features are associated to specific process descriptions. The Meta_ProcessID links to the NHDMetadata table.
OBJECTID Internal feature or event number. OBJECTID false
Permanent_Identifier A 40-character globally unique ID (GUID) value that uniquely identifies the occurrence of each feature or event in The National Map. Text false 40

NHDFlow : Table containing values derived from the topologic connectivity of the geometric network and values of FlowDir attribute of NHDFlowline features. This table is not populated in pre-processed subregions.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
DeltaLevel Numerical difference between StreamLevel for From feature and stream level for To feature. Long Integer true 0 Only populated if StreamLevel has been calculated.
Direction Text or Code to describe direction of flow. Long Integer true 0 Flow direction domain values: In, Network Start, Network End, and Non-flowing.
From_Permanent_Identifier Permanent_Identifier of feature from which the water flows. Text false 40 Feature already assigned a ComID retains that value as the Permanent_ Identifier.
OBJECTID Internal feature or event number. OBJECTID false
To_Permanent_Identifier Permanent_Identifier of feature to which the feature flows. Text false 40 Feature already assigned a ComID retains that value as the Permanent_ Identifier.

NHDFlowlineVAA : NHDFlowline Value Added Attributes table. Table derived entirely from the NHDFlowline features and the NHDFlow table values.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
ArbolateSumKM Sum of the lengths of all the drains that drain to the downstream end of the current drain. Double true 0
DivergenceFlag If this drain is 1 branch of a flow split, 1=drain is main branch, 2=otherwise, 0= drain not a branch of flow split. Long Integer true 0
DnDrainCount Number of drains immediately downstream. Long Integer true 0
DnLevel Stream level of drain. Long Integer true 0
DnLevelPathID Level path ID of downstream drain. Double true 0
DnMinHydroSeq At a divergence, the Hydro sequence number of the minor downstream drain. Double true 0
FDate Date of last feature modification. Date false 0 8
FromNode Nationally unique ID for the "from" node endpoint of the drain. Double true 0
HydroSeq Nationally unique sequence number that places the reach in hydrologic sequence. Double true 0
LevelPathID Hydro Sequence No. of downstream drain that is on the same level path as this drain according to the DFlow Table. Double true 0
OBJECTID Internal feature or event number. OBJECTID false
PathLengthKM Distance from this drain pourpoint to its terminal drain's pourpoint according to the DFlow Table. Double true 0
Permanent_Identifier A 40-character globally unique ID (GUID) value that uniquely identifies the occurrence of each feature or event in The National Map. Text false 40
StartFlag Set to '1' if the drain is a headwater drain according to the DFlow Table, otherwise '0'. Long Integer true 0 NoYesDomain
StreamLevel Drain_level of the downstream mainstem drain. Long Integer true 0
StreamOrder Strahler stream order number for the drain. Long Integer true 0
TerminalFlag Set to '1' if drain is a terminal drain (flows into ocean, Great Lakes, Canada, Mex. or the ground) otherwise set to '0'. Long Integer true 0 NoYesDomain
TerminalPathID Hydrologic sequence number of terminal flowline. Double true 0
ThinnerCode Ordinal value designed to allow selection of progressively more dense networks. Least dense network=1. Long Integer true 0
ToNode Nationally unique ID for the "to" node endpoint of the drain. Double true 0
UpHydroSeq Hydro Sequence No. of upstream mainstem drain. Double true 0
UpLevelPathId LevelPathID of upstream mainstem drain. Double true 0
UpMinHydroSeq Minimum Hydro Sequence No. of all upstream drains. Double true 0

NHDMetadata : This table contains FGDC compliant data quality information.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
Address Address line for the address. Text true 100
AddressType Information provided by the address. Text true 40
AttributeAccuracyReport Explanation of entities and assignments of values in dataset. Text true 1800
City City of the address. Text true 40
CompletenessReport Information about omissions, criteria, definitions used to derive dataset. Text true 2400
ContactEmailAddress E-mail address to reach contact organization or individual. Text true 40
ContactInstructions Supplemental instructions to contact Organization or individual. Text true 120
ContactOrganization Name or organization to which type of contact applies. Text true 100
ContactVoiceTelephone Telephone number to reach Organization or individual. Text true 40
DataSetCredit Recognition of those who contributed to the dataset. Text true 4000
HorizPositionalAccuracyReport Horizontal coordinate measurements and description of tests used. Text true 3100
LogicalConsistencyReport Explanation of fidelity of relationships in dataset and tests used. Text true 1000
Meta_ProcessID 40-char GUID value that uniquely identifies a metadata process description in The National Map. Text false 40 Features are associated to specific process descriptions. The Meta_ProcessID links to the NHDMetadata table.
MetadataDate Date the metadata was last created or updated. Date true 0 8
MetadataStandardName Name of the metadata standard used to document the dataset. Text true 100
MetadataStandardVersion Identification of the version of the metadata standard used to document the dataset. Text true 40
OBJECTID Internal feature or event number. OBJECTID false
PostalCode ZIP or other postal code of the address. Text true 20
ProcessDate Date when the event was completed. Date false 0 8
ProcessDescription Explanation of the event and related parameters or tolerances. Text false 4000
StateOrProvince State or province of the address. Text true 30
VertPositionalAccuracyReport Vertical coordinate measurements and description of tests used. Text true 3100

NHDPlusDivFracMP : Contains specifications about the fraction of a cumulative attribute to be routed through each path in a divergence

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
DivFrac Fraction for routing cumulative attrbutes down flowline paths in a divergence Double true 0 Alias "DivergenceFraction"
NHDPlusID NHDPlus HR Unique identifier of a NHDFlowline feature. Found in NHDPlus HR Only. Double true This field only exists when NHD feature classes are brought into NHDPlus HR.
NodeNumber Unique identifier for the point at the top of the NHDFlowlien feature Double true 0
OBJECTID Internal feature or event number. OBJECTID false
StatusFlag Flag reserved for use during NHDPlus Build/Refresh Process Text true 1 StatusFlag Domain
VPUID Vector Processing Unit Identifier. Found in NHDPlus HR only. Text true 8 This field only exists when NHD feature classes are brought into NHDPlus HR.

NHDPlusEROMQAMA : A table that holds QA statistics for the EROM mean annual flow estimates

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
GageID NWIS GageID value Text true
GageRef Identifies if gage is Falcone Reference: 0=No, 1=Yes Short Integer true
NHDPlusID NHDPlus HR Unique identifier of a NHDFlowline feature. Found in NHDPlus HR Only. Double true This field only exists when NHD feature classes are brought into NHDPlus HR.
OBJECTID Internal feature or event number. OBJECTID false
QA Cumulative runoff (cfs) Double true
QADelta QE – QA (cfs) Double true
QAURoDelt Q_Eunitro – Q_Aunitro (cfs/sqkm) Double true
QAUnitRo QA / DivDASqKm (cfs/sqkm) Double true
QB QA – Excess ET (EET) (cfs) Double true
QBDelta QE – QB (cfs) Double true
QBURoDelt Q_Eunitro – Q_Bunitro (cfs/sqkm) Double true
QBUnitRo QB / DivDASqKm (cfs/sqkm) Double true
QC QA - EET +/- Refgage Regression Adjustment (cfs) Double true
QCDelta QE – QC (cfs) Double true
QCURoDelt Q_Eunitro – Q_Cunitro (cfs/sqkm) Double true
QCUnitRo QC / DivDASqKm (cfs/sqkm) Double true
QD QA – EET +/ Refgage Regression Adjustment +/- PlusFlowAR (cfs) Double true
QDDelta QE – QD (cfs) Double true
QDURoDelt Q_Eunitro – Q_Dunitro (cfs/sqkm) Double true
QDUnitRo QD / DivDASqKm (cfs/sqkm) Double true
QE Gage flow (cfs) Double true
QEUnitRo QE / DivDASqKm (cfs/sqkm) Double true
VPUID Vector Processing Unit Identifier. Found in NHDPlus HR only. Text true 8 This field only exists when NHD feature classes are brought into NHDPlus HR.

NHDPlusEROMQARPT : QA Report for each Vector Processing Unit(VPU) in run

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
OBJECTID Internal feature or event number. OBJECTID false
RptLine QA Report for each Vector Processing Unit (VPU) in run Text true 120

NHDPlusFlow : A table that describes flowing and non-flowing connections between NHDFlowline features

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
DeltaLevel Numerical difference between StreamLevel for From feature and stream level for To feature. Long Integer true 0 Only populated if StreamLevel has been calculated.
Direction Common identifier for the downstream NHDFlowline feature Short Integer true
FromPermID Is geometric connection: 0=No (geometric gap); 1=Yes (connected) Text true 40
FromVPUID Flow relationship type Text true 8
GapDistKm Node number at the bottom of FromComID and the top of ToComID Double true
HasGeo Numerical diff between StreamLevels for FromNHDPID and for ToNHDPID Double true
NHDPlusID NHDPlus HR Unique identifier of a NHDFlowline feature. Found in NHDPlus HR Only. Double true This field only exists when NHD feature classes are brought into NHDPlus HR.
NodeNumber Double true
OBJECTID Internal feature or event number. OBJECTID false
ToNHDPID Double true
ToPermID Is geometric connection: 0=No (geometric gap); 1=Yes (connected) Text true 40
ToVPUID Distance between the downstream and upstream ends Text true 8

NHDPlusFlowlineVAA : A table that holds Value Added Attributes (VAAs) for each NHDFlowline feature in the NHDPlusFlow table and is updated by NHDPlus Build/Refresh process. Differs from the NHDFlowlineVAA table

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
ArbolateSu Arbolate Sum - Kms of stream upstream of bottom of NHD Flowline feature Double true
AreaSqKm Area of feature in square kilometers based on Albers Equal Area projection. Double true 0 Computed.
DivDASqKm Divergence-routed cumulative drainage area at downstream end of NHDFlowline feature Double true
Divergence See Divergence Domain for coded values Short Integer true Divergence Domain
DnDrainCou Count of NHDFlowline features immediately downstream Short Integer true
DnHydroSeq Downstream mainstem hydrologic sequence number Double true
DnLevel Streamlevel of main stem downstream NHDflowline feature Short Integer true
DnLevelPat Downstream mainstem level path identifier Double true
DnMinorHyd Downstream minor hydrologic sequence number Double true
ElevFixed NHDFlowline feature length (kilometers) used to compute slope Short Integer true NoYesDomain
FromMeas Downstream BurnLineEvent Measure (m-value) Double true 0
FromNode Nationally unique ID for the "from" node endpoint of the drain. Double true 0
HWNodeSqKm Catchment area that drains to headwater node of the NHDFlowline feature Double true
HWType Headwater Type; 0=Real headwater, 1=Artificial headwater Short Integer true Headwater Type Domain
HydroSeq Nationally unique sequence number that places the reach in hydrologic sequence. Double true 0
LevelPathI Level Path Identifier – Hydrologic sequence no. of most downstream feature Double true
MaxElevRaw Maximum elevation unsmoothed, in centimeters Double true
MaxElevSmo Maximum elevation smoothed, in centimeters Double true
MinElevRaw Minimum elevation unsmoothed, in centimeters Double true
MinElevSmo Minimum elevation smoothed, in centimeters Double true
NHDPlusID NHDPlus HR Unique identifier of a NHDFlowline feature. Found in NHDPlus HR Only. Double true This field only exists when NHD feature classes are brought into NHDPlus HR.
OBJECTID Internal feature or event number. OBJECTID false
PathLength Distance to terminal NHDFlowline feature downstream along main path Double true
ReachCode Unique identifier. The first eight digits are the WBD_HUC8. The next six digits are randomly assigned, sequential numbers that are unique within a HUC8. Text true 14 For event feature classes, this value is the ReachCode on which the event is located.
RtnDiv Returning Divergence Flag Short Integer true NoYesDomain
Slope Slope of flowline (meters/meters) based on smoothed elevations Double true
SlopeLenKm Flag indicating that the downstream elevation is fixed, i.e.; not smoothed Double true
StartFlag Set to '1' if the drain is a headwater drain according to the DFlow Table, otherwise '0'. Long Integer true 0 NoYesDomain
StatusFlag Flag reserved for use during NHDPlus Build/Refresh Process Text true 1 StatusFlag Domain
StreamCalc Stream Calculator Short Integer true
StreamLeve Stream level Short Integer true
StreamOrde Modified Strahler Stream Order Short Integer true
TerminalFl 0=not a terminal NHDFlowline feature; 1=a terminal NHDFlowline feature Short Integer true
TerminalPa Terminal Path Identifier - Hydrologic sequence number of terminal Double true
Thinner Not valued; Reserved for future use Short Integer true
ToMeas Upstream BurnLineEvent Measure (m-value) Double true 0
ToNode Nationally unique ID for the "to" node endpoint of the drain. Double true 0
TotDASqKm Total upstream cumulative drainage area at downstream end of NHDFlowline feature Double true
UpHydroSeq Hydro Sequence No. of upstream mainstem drain. Double true 0
UpLevelPat Upstream mainstem level path identifier Double true
VPUID Vector Processing Unit Identifier. Found in NHDPlus HR only. Text true 8 This field only exists when NHD feature classes are brought into NHDPlus HR.
VPUIn Are there VPU inflows? 0(no) or 1(yes) Short Integer true NoYesDomain
VPUOut Are there VPU outflows? 0(no) or 1(yes) Short Integer true NoYesDomain

NHDPlusIncrLat : Mean latitude of each NHDPlusV2 catchment

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
ComID A value that uniquely identifies each feature in the Medium-Resolution NHD, NHDPlus Version 1, and NHDPlus Version 2 NHDFlowline data. The ComID also corresponds to the Permanent_Identifier in the High-Resolution NHD NHDFlowline data for Alaska, Puerto Rico, and the U.S. Virgin Islands (unless an NHDFlowline feature is updated and assigned a new value for its Permanent_Identifier). This attribute links 1:1M features to feature classes and attribute tables in the NHD and NHDPlus datasets. Because many features were split during the creation of the 1:1M data, there may be multiple features with the same value. Long Integer true There is no predefined set of valid ComID values. A value of "-999" means "There is no ComID because the stream did not come from the NHD or NHDPlus".
HydroSeq Nationally unique sequence number that places the reach in hydrologic sequence. Double true 0
MeanLat Mean latitude in degrees Double true
MissLat Area of catchment with no data Double true
OBJECTID Internal feature or event number. OBJECTID false
VPUID Vector Processing Unit Identifier. Found in NHDPlus HR only. Text true 8 This field only exists when NHD feature classes are brought into NHDPlus HR.

NHDPlusIncrPrecipMA : Mean annual precipitation averaged over the area of each catchment

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
HydroSeq Nationally unique sequence number that places the reach in hydrologic sequence. Double true 0
MissPMA Area of catchment with no data Double true
NHDPlusID NHDPlus HR Unique identifier of a NHDFlowline feature. Found in NHDPlus HR Only. Double true This field only exists when NHD feature classes are brought into NHDPlus HR.
OBJECTID Internal feature or event number. OBJECTID false
PrecipMA Mean annual precipitation in millimeters x 100 Double true
VPUID Vector Processing Unit Identifier. Found in NHDPlus HR only. Text true 8 This field only exists when NHD feature classes are brought into NHDPlus HR.

NHDPlusIncrPrecipMM01 to MM12 : Mean monthly precipitation averaged over the area of each catchment

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
HydroSeq Nationally unique sequence number that places the reach in hydrologic sequence. Double true 0
MissPMM01 Area of catchment with no data Double true
NHDPlusID NHDPlus HR Unique identifier of a NHDFlowline feature. Found in NHDPlus HR Only. Double true This field only exists when NHD feature classes are brought into NHDPlus HR.
OBJECTID Internal feature or event number. OBJECTID false
PrecipMM01 Mean monthly precipitation in millimeters x 100 Double true
VPUID Vector Processing Unit Identifier. Found in NHDPlus HR only. Text true 8 This field only exists when NHD feature classes are brought into NHDPlus HR.

NHDPlusIncrROMA : Mean annual runoff values

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
HydroSeq Nationally unique sequence number that places the reach in hydrologic sequence. Double true 0
MissRMA Area of catchment with no data Double true
NHDPlusID NHDPlus HR Unique identifier of a NHDFlowline feature. Found in NHDPlus HR Only. Double true This field only exists when NHD feature classes are brought into NHDPlus HR.
OBJECTID Internal feature or event number. OBJECTID false
RunOffMA Mean runoff (mm) Double true
VPUID Vector Processing Unit Identifier. Found in NHDPlus HR only. Text true 8 This field only exists when NHD feature classes are brought into NHDPlus HR.

NHDPlusIncrTempMA : Mean annual precipitation averaged over the area of each catchment

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
HydroSeq Nationally unique sequence number that places the reach in hydrologic sequence. Double true 0
HydroSeq Hydrologic sequence Double true
NHDPlusID NHDPlus HR Unique identifier of a NHDFlowline feature. Found in NHDPlus HR Only. Double true This field only exists when NHD feature classes are brought into NHDPlus HR.
OBJECTID Internal feature or event number. OBJECTID false
TempMA Mean annual temperature in degrees centigrade x 100 Double true
VPUID Vector Processing Unit Identifier. Found in NHDPlus HR only. Text true 8 This field only exists when NHD feature classes are brought into NHDPlus HR.

NHDPlusIncrTempMM01 to MM12 : Mean monthly temperature averaged over the area of each catchment

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
HydroSeq Nationally unique sequence number that places the reach in hydrologic sequence. Double true 0
MissRMM01 Area of catchment with no data Double true
NHDPlusID NHDPlus HR Unique identifier of a NHDFlowline feature. Found in NHDPlus HR Only. Double true This field only exists when NHD feature classes are brought into NHDPlus HR.
OBJECTID Internal feature or event number. OBJECTID false
TempMM02 Mean monthly temperature in degrees centigrade x 100 Double true
VPUID Vector Processing Unit Identifier. Found in NHDPlus HR only. Text true 8 This field only exists when NHD feature classes are brought into NHDPlus HR.

NHDPlusMegaDiv : A table that holds PlusFlow records for divergences that have two or more outflow paths

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
FromNHDPID Common identifier of the upstream NHDFlowline feature Double true
OBJECTID Internal feature or event number. OBJECTID false
ToNHDPID Common identifier of the downstream NHDFlowline feature Double true
VPUID Vector Processing Unit Identifier. Found in NHDPlus HR only. Text true 8 This field only exists when NHD feature classes are brought into NHDPlus HR.

NHDProcessingParameters : This table lists the schema and the version of the master NHD database that was used to generate extracted NHD data. This table is most useful to USGS to verify the version used by data stewards for updates.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
OBJECTID Internal feature or event number. OBJECTID false
ParameterName The name of the parameter. Text false 24 ParameterName Domain Parameters include Version, Resolution, Processing_Organization and SchemaVersion
ParameterValue The value for the parameter. Text false 100

NHDReachCodeMaintenance : Table used to maintain links for backward compatibility with FOD-based systems.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
GNIS_ID A permanent, unique number assigned by the Geographic Names Information System (GNIS) to a geographic feature name for the sole purpose of uniquely identifying that name application as a record in any information system database, dataset, file, or document Text true 10 GNIS_ID = "null" if no name is associated with the feature. Removed from WBD as of version 2.3 schema.
GNIS_Name The Geographic Names Information System (GNIS) assigned proper name, specific term, or expression by which a particular geographic entity is known. Text true 100
OBJECTID Internal feature or event number. OBJECTID false
Permanent_Identifier A 40-character globally unique ID (GUID) value that uniquely identifies the occurrence of each feature or event in The National Map. Text false 40
ReachCode Unique identifier. The first eight digits are the WBD_HUC8. The next six digits are randomly assigned, sequential numbers that are unique within a HUC8. Text true 14 For event feature classes, this value is the ReachCode on which the event is located.
ReachSMDate Reach spatial modification date. Date true 0 8 The ReachCodeMaintenance table is updated by the NHD Update Tool. When a geometric edit is performed on a feature that contains a ReachCode (NHDFlowline or NHDWaterbody), the NHDReachCodeMaintenance table is updated to the current date to reflect the last spatial modification (SM) date of the associated ReachCode. Any previous records for that Resolution (Medium or High, depending on the target feature class resolution) are overwritten. The Permanent_Identifier field is unique to this table and is not related to NHDFlowline or Waterbody features. The GNIS_ID and GNIS_Name are updated, as these are unique per ReachCode. MValue updates are not considered spatial modifications and thus do not trigger ReachSMDate updates. For events (NHDPointEvent, NHDLineEvent, NHDAreaEvent), when an event is created by the Hydrography Event Management (HEM) Tool, the tool pulls the current ReachSMDate from the ReachCodeMaintenance table for the ReachCode the event is associated with. So, if underlying hydrography features are updated, and events are not, the ReachSMDate in the event table will be out of date in relation to the current hydrography. Users can either synchronize their events using the HEM Tool or they may not, depending on their needs. For example, a user may not want to synchronize their events to the current hydrography if a study was performed on a certain version of the NHD.
Resolution Source resolution. Long Integer false 0 Resolution Currently NHD is available as separate resolutions. Domain values: Local > 1:12,000 High 1:24,000/12,000 Medium 1:100,000

NHDReachCrossReference : Information that tracks changes, over time, to reach codes.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
ChangeCode Type of change to the reached feature. Text true 4
NewHUCode Hydrologic Unit of feature after migration. Text true 8 Used if the flowline was originally assigned a reach code based on an incorrect subbasin assignment.
NewReachCode Reach code after the change. Text true 17
NewReachDate Date new reach code was assigned (yyyymmdd). Date true 0
NewUPMI Upstream Marker Index of Old Reach (RF-3-Alpha Only). Text true 5
OBJECTID Internal feature or event number. OBJECTID false
OldHUCode Hydrologic Unit of feature prior to migration. Text true 8 Used if the flowline was originally assigned a reach code based on an incorrect subbasin assignment.
OldReachCode Reach code prior to change. Text true 17
OldReachDate Date old reach code was assigned. Date true 0 8
OldUPMI Upstream Marker Index of Old Reach (RF-3-Alpha Only). Text true 5
Process Name of the process that created the reach code change. Text true 6 Process Domain Many processes to create the NHD were done on the National Database and these have standard codes.
ReachFileVersion Reach File Version in which the change became effective. Text true 10 ReachFileVersion Domain

NHDSourceCitation : This table links to process description information found in the NHDMetadata table. Not all process descriptions have a source citation. Content is based on FGDC Metadata requirements.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
BeginningDate First year of the event (if Range_of_Dates applies). Date true 0 if CalendarDate is used.
CalendarDate The year (if Single Date applies). Date true 0 8 if BeginningDate and EndingDate are used.
EndingDate Last year for the event (if Range_of_Dates applies). Date true 0 if CalendarDate is used.
Meta_ProcessID 40-char GUID value that uniquely identifies a metadata process description in The National Map. Text false 40 Features are associated to specific process descriptions. The Meta_ProcessID links to the NHDMetadata table.
OBJECTID Internal feature or event number. OBJECTID false
Originator Name of an organization or individual that developed the dataset. Text true 400
PublicationDate Date the dataset is published or made available for release. Date true 0 8
SourceCitationAbbreviation Short form alias for source citation. Text true 255
SourceContribution Brief statement identifying information contributed by source to dataset. Text true 750
SourceCurrentnessReference The basis on which the source time period of content information of the source data set is determined. Text true 255
SourceScaleDenominator Denomination of representative fraction on a map. Long Integer true 0
Source_DatasetID Unique permanent ID value which uniquely identifies a source dataset used in The National Map. Text false 40
Title Name by which the dataset is known. Text true 255
TypeOfSourceMedia The medium of the source dataset, i.e. paper, CD-ROM, online, or other sources. Text true 255

NHDStatus : NHDStatus is used to track data changes for transaction uploads to the central repository. This table is only populated during editing. It is blank when NHD is downloaded for use.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
ID Temporary ID assigned to track feature edits. Text false 0 40 When edits are loaded into the national database, the temporary ID is replaced with an official PermID.
OBJECTID Internal feature or event number. OBJECTID false
Permanent_Identifier A 40-character globally unique ID (GUID) value that uniquely identifies the occurrence of each feature or event in The National Map. Text false 40
Status Type of edit. Long Integer false 0 UpdateStatus Domain

NHDVerticalRelationship : The table documents the vertical relationship for features (i.e. streams and canals) which cross but do not exchange flow.

NameDefinitionTypeAllow NullsPrecisionLengthDomainDefault ValueComments
Above_Permanent_Identifier Permanent_Identifier of feature above the vertical offset. Text false 40 Feature already assigned a ComID retains that value as the Permanent_ Identifier.
Below_Permanent_Identifier Permanent_Identifier of feature below the vertical offset. Text false 40 Feature already assigned a ComID retains that value as the Permanent_ Identifier.
OBJECTID Internal feature or event number. OBJECTID false
Permanent_Identifier A 40-character globally unique ID (GUID) value that uniquely identifies the occurrence of each feature or event in The National Map. Text false 40




FEATURE DOMAINS (FCODE DOMAINS)


Area of Complex Channels FCode

Feature CodeFeature DescriptionFeature Definition
53700Area of Complex Channels (no attributes)An area where a stream or river flows in an intricate network of sediment-driven interlacing channels. Not named features.

Area to be Submerged FCode

Feature CodeFeature DescriptionFeature Definition
30700Area to be Submerged (no attributes)The known extent of the intended lake that will be created behind a dam under construction. May be named feature.

ArtificialPath FCode

Feature CodeFeature DescriptionFeature Definition
55800Artificial Path (no attributes)A surrogate for general flow direction in NHDWaterbodies and NHDAreas. Artificial Paths carry the name of the flowline feature. NHDArea StreamRivers will have an Artificial Path that will carry the name of the river.

BayInlet FCode

Feature CodeFeature DescriptionFeature Definition
31200BayInlet (no attributes)A water area that is an opening of the sea/ocean into the land, or of an estuary, lake, or river into its shore. BayInlets are used in the NHD to provide named areas for other hydrographic features, and must overlap Estuary, LakePond, SeaOcean, or StreamRiver. May be named feature.

Bridge FCode

Feature CodeFeature DescriptionFeature Definition
31800Bridge (no attributes)A structure spanning and providing passage of a waterway over another waterway, railroad, or other obstacle. Bridge also exists as an NHDLine. May be a named feature.

CanalDitch FCode

Feature CodeFeature DescriptionFeature Definition
33600CanalDitch (CanalDitch Type = null)An artificial open waterway constructed to transport water, to irrigate or drain land, to connect two or more bodies of water, or to serve as a waterway for watercraft. May be a named feature.
33601CanalDitch (CanalDitch Type = Aqueduct)An artificial, open waterway designed to transport domestic or industrial water from a supply source to a distribution point, often by gravity.
33603CanalDitch (CanalDitch Type = Stormwater)An artificial, open waterway designed to convey stormwater through and from a drainage area.

Coastline FCode

Feature CodeFeature DescriptionFeature Definition
56600Coastline (no attributes)A line of contact between the open sea and the land, including imaginary lines separating inland water bodies from the open sea. The NHD acquires coastline data from the National Ocean and Atmospheric Agency (NOAA) and it is not a product of the USGS. Coastline in the NHD is a representation of the Mean High Water (MHW) as calculated by NOAA and may not match orthoimagery. Coastline in the NHD could be altered but must have an accompanying metadata record that identifies the scientific method used to calibrate the coastline to a known vertical datum. Coastline may be a named feature.

Connector FCode

Feature CodeFeature DescriptionFeature Definition
33400Connector (no attributes)A known, but nonspecific, invisible connection between two nonadjacent network segments.

DamWeir FCode

Feature CodeFeature DescriptionFeature Definition
34300DamWeir (Construction Material = null)A barrier constructed to control the flow or raise the level of water. No information on the predominant construction material.
34305DamWeir (Construction Material = Earthen)A barrier constructed to control the flow or raise the level of water where the predominant material used in construction is earth, or a combination of earth and rock.
34306DamWeir (Construction Material = Nonearthen)A barrier constructed to control the flow or raise the level of water where the predominant material used in construction is concrete, brick, or stone. Coincident with a Nonearthen Shore Feature.

Drainageway FCode

Feature CodeFeature DescriptionFeature Definition
46800DrainagewayDrainageway features are flowlines delineated where terrain modelling indicates potential headwater drainage but no channel is detectable. The drainageway code must only be applied at the initiation of flowlines or confluence of other drainageway features. The drainageway code must not be applied downstream of other non-drainageway NHD flowlines or waterbody features.

Estuary FCode

Feature CodeFeature DescriptionFeature Definition
49300Estuary (no attributes)An estuary is a semi-enclosed coastal body of water which has a free connection with the open sea and within which sea water is measurably diluted with fresh water derived from land drainage" (Cameron and Pritchard, 1963). An Estuary is defined by the NOAA's Coastal Aquatic Framework (CAF) or local information concerning the extent of the mixed zone of fresh and salt water.

Flume FCode

Feature CodeFeature DescriptionFeature Definition
36200Flume (no attributes)An open, inclined, artificial channel constructed of wood, metal, or concrete; generally elevated. Flume also exists as an NHDLine. May be a named feature.

Foreshore FCode

Feature CodeFeature DescriptionFeature Definition
36400Foreshore (no attributes)The area of shore that lies between the limits of the mean high water (MHW) and mean low low water (MLLW) tidal marks and is exposed during low tides. The NHD acquires Foreshore data from the National Ocean and Atmospheric Agency (NOAA) and it is not a product of the USGS. May be a named feature.

Gaging Station FCode

Feature CodeFeature DescriptionFeature Definition
36700Gaging Station (no attributes)A structure used to measure the characteristics of a hydrographic feature. Stream Gages are usually captured on the flowline and not necessarily on the physical location of the monitoring station. Stream Gages are also available as a Point Event. Not a named feature.
36701Gaging Station: Gaging Station Status=Active; Record=ContinuousA structure used to measure the characteristics of a hydrographic feature. Stream Gages are usually captured on the flowline and not necessarily on the physical location of the monitoring station. A site is considered active if: (1) it has collected time-series (automated) data within the last 183 days (6 months), or (2) it has collected discrete (manually collected) data within 397 days (13 months). Where data collection is continuous, data may be available in real-time, as individual observations, or as daily summaries.

Gate FCode

Feature CodeFeature DescriptionFeature Definition
36900Gate (no attributes)A structure that may be swung, drawn, or lowered to block an entrance or passageway. Gate may also be found as a line feature. Gate also exists as an NHDLine. Not a named feature.

Ice Mass FCode

Feature CodeFeature DescriptionFeature Definition
37800Ice Mass (no attributes)A field of ice usually formed in regions of perennial frost. Ice Mass primarily consists of glaciers. May be a named feature.

Inundation Area FCode

Feature CodeFeature DescriptionFeature Definition
40300Inundation Area (Innundation Control Status = null, Stage = null)An area of land subject to flooding. No information on the existence of functional structures controlling the flow of water into the area. No information on the height of the water surface.
40307Inundation Area (Innundation Control Status = Not Controlled, Stage = null)An area of land subject to flooding. No controlling structures exist; flooding is natural and periodic. No information on the height of the water surface.
40308Inundation Area (Innundation Control Status = Controlled, Stage = null)An area of land subject to flooding. Functional structures such as a levee or DamWeir, exist to control the water and inundate specific areas. No information on the height of the water surface.
40309Inundation Area (Innundation Control Status = Controlled, Stage = Flood Elevation)An area of land subject to flooding. Functional structures, such as a levees or DamWeirs, exist to control the water and inundate specific areas. Height of the surface water is flood elevation (the stage that prevails when a natural water body is at or near capacity).

LakePond FCode

Feature CodeFeature DescriptionFeature Definition
39000LakePond (Hydrographic Category = null, Stage = null)A standing body of water with a predominantly natural shoreline surrounded by land or a flooded river system where a dam has been built to withhold water. Portion of the year the LakePond contains water is unknown. Height of the water surface is unknown.
39001LakePond (Hydrographic Category = Intermittent, Stage = null)A standing body of water with a predominantly natural shoreline surrounded by land or a flooded river system where a dam has been built to withhold water. Contains water for only part of the year, but more than just after rainstorms and at snowmelt. Height of the water surface is unknown.
39004LakePond (Hydrographic Category = Perennial, Stage = null)A standing body of water with a predominantly natural shoreline surrounded by land or a flooded river system where a dam has been built to withhold water. Contains water throughout the year, except for infrequent periods of severe drought. Height of the water surface is unknown.
39005LakePond (Hydrographic Category = Intermittent, Stage = High Water Elevation)A standing body of water with a predominantly natural shoreline surrounded by land or a flooded river system where a dam has been built to withhold water. Contains water for only part of the year, but more than just after rainstorms and at snowmelt. Height of the water surface is the stage that prevails when a natural water body is at or near capacity.
39006LakePond (Hydrographic Category = Intermittent, Stage = Date of Photography)A standing body of water with a predominantly natural shoreline surrounded by land or a flooded river system where a dam has been built to withhold water. Contains water for only part of the year, but more than just after rainstorms and at snowmelt. Height of the water surface is the stage that exists at the date of the photography.
39009LakePond (Hydrographic Category = Perennial, Stage = Average Water Elevation)A standing body of water with a predominantly natural shoreline surrounded by land or a flooded river system where a dam has been built to withhold water. Contains water throughout the year, except for infrequent periods of severe drought. Height of the water surface is the the stage of a natural water body that prevails for the greater part of the year.
39010LakePond (Hydrographic Category = Perennial, Stage = Normal Pool)A standing body of water with a predominantly natural shoreline surrounded by land or a flooded river system where a dam has been built to withhold water. Contains water throughout the year, except for infrequent periods of severe drought. Height of the water surface is the stage of an artificially impounded water body that prevails for the greater part of the year.
39011LakePond (Hydrographic Category = Perennial, Stage = Date of Photography)A standing body of water with a predominantly natural shoreline surrounded by land or a flooded river system where a dam has been built to withhold water. Contains water throughout the year, except for infrequent periods of severe drought. Height of the water surface is the stage that exists at the date of the photography.
39012LakePond (Hydrographic Category = Perennial, Stage = Spillway Elevation)A standing body of water with a predominantly natural shoreline surrounded by land or a flooded river system where a dam has been built to withhold water. Contains water throughout the year, except for infrequent periods of severe drought. Height of the water surface is the stage of an artificially impounded water body as determined by the spillway.

Levee FCode

Feature CodeFeature DescriptionFeature Definition
56800Levee (no attributes)An embankment built to prevent flooding or to control or confine the flow of liquids. Levee also exists as an NHDLine. Not a named feature.

Lock Chamber FCode

Feature CodeFeature DescriptionFeature Definition
39800Lock Chamber (no attributes)An enclosure on a waterway used to raise and lower vessels as they pass from one level to another. Lock Chamber also exists as an NHDPoint or as an NHDLine. May be a named feature.

Nonearthen Shore FCode

Feature CodeFeature DescriptionFeature Definition
41100Nonearthen Shore (no attributes)A structure built of stone, brick, concrete, or other building materials that borders a body of water. Not a named feature.

Pipeline FCode

Feature CodeFeature DescriptionFeature Definition
42800Pipeline (Product = null, Pipeline Type = null, Relationship to Surface = null)A closed conduit, with pumps, valves and control devices, for conveying fluids, gases, or finely divided solids. Type of product conveyed by pipeline unknown. Type of function or purpose of pipeline unknown. Vertical location of pipeline relative to the surface unknown.
42801Pipeline (Product = water, Pipeline Type = Aqueduct, Relationship to Surface = At or near)A closed conduit, with pumps, valves and control devices, for conveying fluids, gases, or finely divided solids. Aqueduct pipeline, designed to transport domestic or industrial water from a supply source to a distribution point, often by gravity. Vertical location of pipeline is at or near the surface.
42802Pipeline (Product = water, Pipeline Type = Aqueduct, Relationship to Surface = Elevated)A closed conduit, with pumps, valves and control devices, for conveying fluids, gases, or finely divided solids. Aqueduct pipeline, designed to transport domestic or industrial water from a supply source to a distribution point, often by gravity. Vertical location of pipeline is elevated (supported above the earth).
42803Pipeline (Product = water, Pipeline Type = Aqueduct, Relationship to Surface = Underground)A closed conduit, with pumps, valves and control devices, for conveying fluids, gases, or finely divided solids. Aqueduct pipeline, designed to transport domestic or industrial water from a supply source to a distribution point, often by gravity. Vertical location of pipeline is underground (buried below the surface).
42804Pipeline (Product = water, Pipeline Type = Aqueduct, Relationship to Surface = Underwater)A closed conduit, with pumps, valves and control devices, for conveying fluids, gases, or finely divided solids. Aqueduct pipeline, designed to transport domestic or industrial water from a supply source to a distribution point, often by gravity. Vertical location of pipeline is underwater (always submerged).
42805Pipeline (Product = water, Pipeline Type = General Case, Relationship to Surface = At or near)A closed conduit, with pumps, valves and control devices, for conveying fluids, gases, or finely divided solids. General case (common use) pipeline, used to channel flowing water to another site. Vertical location of pipeline is at or near the surface.
42806Pipeline (Product = water, Pipeline Type = General Case, Relationship to Surface = Elevated)A closed conduit, with pumps, valves and control devices, for conveying fluids, gases, or finely divided solids. General case (common use) pipeline, used to channel flowing water to another site. Vertical location of pipeline is elevated (supported above the earth).
42807Pipeline (Product = water, Pipeline Type = General Case, Relationship to Surface = Underground)A closed conduit, with pumps, valves and control devices, for conveying fluids, gases, or finely divided solids. General case (common use) pipeline, used to channel flowing water to another site. Vertical location of pipeline is underground (buried below the surface).
42808Pipeline (Product = water, Pipeline Type = General Case, Relationship to Surface = Underwater)A closed conduit, with pumps, valves and control devices, for conveying fluids, gases, or finely divided solids. General case (common use) pipeline, used to channel flowing water to another site. Vertical location of pipeline is underwater (always submerged).
42809Pipeline (Product = water, Pipeline Type = Penstock, Relationship to Surface = At or near)A closed conduit, with pumps, valves and control devices, for conveying fluids, gases, or finely divided solids. Penstock pipeline, designed to convey water into the turbine of a hydroelectric generating plant. Vertical location of pipeline is at or near the surface.
42810Pipeline (Product = water, Pipeline Type = Penstock, Relationship to Surface = Elevated)A closed conduit, with pumps, valves and control devices, for conveying fluids, gases, or finely divided solids. Penstock pipeline, designed to convey water into the turbine of a hydroelectric generating plant. Vertical location of pipeline is elevated (supported above the earth).
42811Pipeline (Product = water, Pipeline Type = Penstock, Relationship to Surface = Underground)A closed conduit, with pumps, valves and control devices, for conveying fluids, gases, or finely divided solids. Penstock pipeline, designed to convey water into the turbine of a hydroelectric generating plant. Vertical location of pipeline is underground (buried below the surface).
42812Pipeline (Product = water, Pipeline Type = Penstock, Relationship to Surface = Underwater)A closed conduit, with pumps, valves and control devices, for conveying fluids, gases, or finely divided solids. Penstock pipeline, designed to convey water into the turbine of a hydroelectric generating plant. Vertical location of pipeline is underwater (always submerged).
42813Pipeline (Product = water, Pipeline Type = Siphon, Relationship to Surface = Unspecified)A closed conduit, with pumps, valves and control devices, for conveying fluids, gases, or finely divided solids. Siphon pipeline, designed to convey water by gravitational force over, or under, an obstruction. Vertical location of pipeline is The value is not known and is not required.
42814Pipeline (Product = water, Pipeline Type = General Case, Relationship to Surface = null)A closed conduit, with pumps, valves and control devices, for conveying fluids, gases, or finely divided solids. General case (common use) pipeline, used to channel flowing water to another site. Vertical location of pipeline is unknown.
42815Pipeline (Product = water, Pipeline Type = Penstock, Relationship to Surface = null)A closed conduit, with pumps, valves and control devices, for conveying fluids, gases, or finely divided solids. Penstock pipeline, designed to convey water into the turbine of a hydroelectric generating plant. Vertical location of pipeline is unknown.
42816Pipeline (Product = water, Pipeline Type = Aqueduct, Relationship to Surface = null)A closed conduit, with pumps, valves and control devices, for conveying fluids, gases, or finely divided solids. Aqueduct pipeline, designed to transport domestic or industrial water from a supply source to a distribution point, often by gravity. Vertical location of pipeline is unknown.
42820Pipeline (Product = water, Pipeline Type = Stormwater, Relationship to Surface = null)A closed conduit, with pumps, valves and control devices, for conveying fluids, gases, or finely divided solids. Stormwater pipeline, designed to convey stormwater through and from a drainage area. Vertical location of pipeline is unknown.
42821Pipeline (Product = water, Pipeline Type = Stormwater, Relationship to Surface = At or near)A closed conduit, with pumps, valves and control devices, for conveying fluids, gases, or finely divided solids. Stormwater pipeline, designed to convey stormwater through and from a drainage area. Vertical location of pipeline is at or near the surface.
42822Pipeline (Product = water, Pipeline Type = Stormwater, Relationship to Surface = Elevated)A closed conduit, with pumps, valves and control devices, for conveying fluids, gases, or finely divided solids. Stormwater pipeline, designed to convey stormwater through and from a drainage area. Vertical location of pipeline is elevated (supported above the earth).
42823Pipeline (Product = water, Pipeline Type = Stormwater, Relationship to Surface = Underground)A closed conduit, with pumps, valves and control devices, for conveying fluids, gases, or finely divided solids. Stormwater pipeline, designed to convey stormwater through and from a drainage area. Vertical location of pipeline is underground (buried below the surface).
42824Pipeline (Product = water, Pipeline Type = Stormwater, Relationship to Surface = Underwater)A closed conduit, with pumps, valves and control devices, for conveying fluids, gases, or finely divided solids. Stormwater pipeline, designed to convey stormwater through and from a drainage area. Vertical location of pipeline is underwater (always submerged).

Playa FCode

Feature CodeFeature DescriptionFeature Definition
36100Playa (no attributes)The flat area at the lowest part of an undrained desert basin, generally devoid of vegetation. May be a named feature.

Rapids FCode

Feature CodeFeature DescriptionFeature Definition
43100Rapids (no attributes)An area of swift current in a stream or river, characterized by standing waves or by boulders and rocks. Rapids also exist as NHDPoint or as NHDLine. May be a named feature.

Reef FCode

Feature CodeFeature DescriptionFeature Definition
43400Reef (no attributes)A Chain of rocks or coral at or near the surface of the water. May be a named feature.

Reservoir FCode

Feature CodeFeature DescriptionFeature Definition
43600Reservoir (Reservoir Type = null, Construction Material = null, Hydrographic Category = null)A constructed basin formed to contain water or other liquids. Function or purpose of resevoir is unknown. Predominant construction material used to construct the reservoir is unknown. The portion of the year the feature contains water is unknown.
43601Reservoir (Reservoir Type = Aquaculture, Construction Material = null, Hydrographic Category = null)A constructed basin formed to contain water or other liquids. Aquaculture reservoir used for rearing finfish, shell fish, or aquatic plants. Predominant construction material used to construct the reservoir is unknown. The portion of the year the feature contains water is unknown.
43603Reservoir (Reservoir Type = Decorative Pool, Construction Material = null, Hydrographic Category = null)A constructed basin formed to contain water or other liquids. Decorative pool reservoir used for improving the aesthetic appearance of the landscape. Predominant construction material used to construct the reservoir is unknown. The portion of the year the feature contains water is unknown.
43604Reservoir (Reservoir Type = Disposal - Tailing Pond, Construction Material = Earthen, Hydrographic Category = null)A constructed basin formed to contain water or other liquids. Tailing pond reservoir used for the disposal of tailing. Predominant construction material used to construct the reservoir is earthen, or a combination of earth and rock. The portion of the year the feature contains water is unknown.
43605Reservoir (Reservoir Type = Disposal - Tailings Pond, Construction Material = null, Hydrographic Category = null)A constructed basin formed to contain water or other liquids. Tailing pond reservoir used for the disposal of tailing. Predominant construction material used to construct the reservoir is unknown. The portion of the year the feature contains water is unknown.
43606Reservoir (Reservoir Type = Disposal - unspecified, Construction Material = null, Hydrographic Category = null)A constructed basin formed to contain water or other liquids. Disposal reservoir (function/purpose is not known and is not required). Predominant construction material used to construct the reservoir is unknown. The portion of the year the feature contains water is unknown.
43607Reservoir (Reservoir Type = Evaporator, Construction Material = null, Hydrographic Category = null)A constructed basin formed to contain water or other liquids. Evaporator reservoir for natural evaporation of water to allow harvesting of mineral concentrates. Predominant construction material used to construct the reservoir is unknown. The portion of the year the feature contains water is unknown.
43608Reservoir (Reservoir Type = Swimming Pool, Construction Material = null, Hydrographic Category = null)A constructed basin formed to contain water or other liquids. Swimming pool reservoir, used for recreation. Predominant construction material used to construct the reservoir is unknown. The portion of the year the feature contains water is unknown.
43609Reservoir (Reservoir Type = Treatment - Cooling Pond, Construction Material = null, Hydrographic Category = null)A constructed basin formed to contain water or other liquids. Treatment reservoir, used as a cooling pond. Predominant construction material used to construct the reservoir is unknown. The portion of the year the feature contains water is unknown.
43610Reservoir (Reservoir Type = Treatment - Filtration Pond, Construction Material = null, Hydrographic Category = null)A constructed basin formed to contain water or other liquids. Treatment reservoir, used as a filtration pond. Predominant construction material used to construct the reservoir is unknown. The portion of the year the feature contains water is unknown.
43611Reservoir (Reservoir Type = Treatment - Settling Pond, Construction Material = Unspecified, Hydrographic Category = null)A constructed basin formed to contain water or other liquids. Treatment reservoir, used as a settling pond. Predominant construction material used to construct the reservoir is not known and is not required. The portion of the year the feature contains water is unknown.
43612Reservoir (Reservoir Type = Treatment - Sewage Treatment Pond, Construction Material = null, Hydrographic Category = null)A constructed basin formed to contain water or other liquids. Treatment reservoir, used as a sewage treatment pond. Predominant construction material used to construct the reservoir is unknown. The portion of the year the feature contains water is unknown.
43613Reservoir (Reservoir Type = Water Storage, Construction Material = Nonearthen, Hydrographic Category = null)A constructed basin formed to contain water or other liquids. Water Storage reservoir, used or long or short-term storage of water. Predominant construction material used to construct the reservoir is concrete, brick, or stone. The portion of the year the feature contains water is unknown.
43614Reservoir (Reservoir Type = Water Storage, Construction Material = Earthen, Hydrographic Category = Intermittent)A constructed basin formed to contain water or other liquids. Water Storage reservoir, used or long or short-term storage of water. Predominant construction material used to construct the reservoir is earth, or a combination of earth and rock. The reservoir contains water for only part of the year, but more than just after rainstorms and at snowmelt.
43615Reservoir (Reservoir Type = Water Storage, Construction Material = Earthen, Hydrographic Category = Perennial)A constructed basin formed to contain water or other liquids. Water Storage reservoir, used or long or short-term storage of water. Predominant construction material used to construct the reservoir is earth, or a combination of earth and rock. The reservoir contains water throughout the year, except for infrequent periods of severe drought.
43617Reservoir (Reservoir Type = Water Storage, Construction Material = null, Hydrographic Category = null)A constructed basin formed to contain water or other liquids. Water Storage reservoir, used or long or short-term storage of water. Predominant construction material used to construct the reservoir is unknown. The portion of the year the feature contains water is unknown.
43618Reservoir (Reservoir Type = Unspecified, Construction Material = Earthen, Hydrographic Category = null)A constructed basin formed to contain water or other liquids. Type of reservoir is not known and is not required. Predominant construction material used to construct the reservoir is earth, or a combination of earth and rock. The portion of the year the feature contains water is unknown.
43619Reservoir (Reservoir Type = Unspecified, Construction Material = Nonearthen, Hydrographic Category = null)A constructed basin formed to contain water or other liquids. Type of reservoir is not known and is not required. Predominant construction material used to construct the reservoir is concrete, brick, or stone. The portion of the year the feature contains water is unknown.
43621Reservoir (Reservoir Type = Water Storage, Construction Material = null, Hydrographic Category = Perennial)A constructed basin formed to contain water or other liquids. Water Storage reservoir, used or long or short-term storage of water. Predominant construction material is unknown. The reservoir contains water throughout the year, except for infrequent periods of severe drought.
43623Reservoir (Reservoir Type = Evaporator, Construction Material = Earthen, Hydrographic Category = null)A constructed basin formed to contain water or other liquids. Evaporator reservoir for natural evaporation of water to allow harvesting of mineral concentrates. Predominant construction material used to construct the reservoir is earth, or a combination of earth and rock. The portion of the year the feature contains water is unknown.
43624Reservoir (Reservoir Type = Treatment, Construction Material = null, Hydrographic Category = null)A constructed basin formed to contain water or other liquids. Treatment reservoir. Predominant construction material used is unknown. The portion of the year the feature contains water is unknown.
43625Reservoir (Reservoir Type = Disposal, Construction Material = earthen, Hydrographic Category = null)A constructed basin formed to contain water or other liquids. Disposal Reservoir. Predominant construction material used to construct the reservoir is unknown. The portion of the year the feature contains water is unknown.
43626Reservoir (Reservoir Type = Disposal, Construction Material = Nonearthen, Hydrographic Category = null)A constructed basin formed to contain water or other liquids. Disposal Reservoir. Predominant construction material used to construct the reservoir is concrete, brick, or stone. The portion of the year the feature contains water is unknown.

Rock FCode

Feature CodeFeature DescriptionFeature Definition
44100Rock (Relationship to Surface = null)A concreted mass of stony material.
44101Rock (Relationship to Surface = Abovewater)A concreted mass of stony material. The vertical location of the rock relative to the surface is above water (exposed at mean lower low water).
44102Rock (Relationship to Surface = Underwater)A concreted mass of stony material. The vertical location of the rock relative to the surface is underwater (always submerged).

SeaOcean FCode

Feature CodeFeature DescriptionFeature Definition
44500SeaOcean (no attributes)The great body of salt water that covers much of the earth. May be a named feature.

SinkRise FCode

Feature CodeFeature DescriptionFeature Definition
45000SinkRise (no attributes)The place at which a stream disappears underground or reappears at the surface in a karst area. SinkRise also exists as an NHDPoint. May be a named feature.

Sounding Datum Line FCode

Feature CodeFeature DescriptionFeature Definition
50300Sounding Datum Line (Positional Accuracy = null)A line representing the bathymetric contour of mean low low water (MLLW) for which a foreshore feature is present or visible. The NHD acquires Sounding Datum Line data from the National Ocean and Atmospheric Agency (NOAA) and it is not a product of the USGS. The accuracy within which the feature may be confidently positioned is unknown.
50301Sounding Datum Line (Positional Accuracy = Approximate)A line representing the bathymetric contour of mean low low water (MLLW) for which a foreshore feature is present or visible. The NHD acquires Sounding Datum Line data from the National Ocean and Atmospheric Agency (NOAA) and it is not a product of the USGS. The accuracy within which the feature may be confidently positioned is approximate (conditions permit the feature to be confidently positioned between 0.02" and 0.1", at map scale, of its true ground position).
50302Sounding Datum Line (Positional Accuracy = Definite)A line representing the bathymetric contour of mean low low water (MLLW) for which a foreshore feature is present or visible. The NHD acquires Sounding Datum Line data from the National Ocean and Atmospheric Agency (NOAA) and it is not a product of the USGS. The accuracy within which the feature may be confidently positioned is definite (conditions permit the feature to be confidently positioned. Horizontal data are confidently positioned within 0.02", at map scale, of the true ground position. Vertical data are confidently positioned within one-half contour interval of the true ground position).

Spillway FCode

Feature CodeFeature DescriptionFeature Definition
45500Spillway (no attributes)A constructed passage for surplus water to run over or around a dam.

SpringSeep FCode

Feature CodeFeature DescriptionFeature Definition
45800SpringSeep (no attributes)A place where water issues from the ground naturally. May be a named feature.

StreamRiver FCode

Feature CodeFeature DescriptionFeature Definition
46000StreamRiver (no attributes)A body of flowing water. Portion of the year the feature contains water unknown.
46003StreamRiver (Hydrographic Category = Intermittent)A body of flowing water that contains water for only part of the year, but more than just after rainstorms and at snowmelt.
46006StreamRiver (Hydrographic Category = Perennial)A body of flowing water that contains water throughout the year, except for infrequent periods of severe drought.
46007StreamRiver (Hydrographic Category = Ephemeral)A body of flowing water that contains water only during or after a local rainstorm or heavy snowmelt.

Submerged Stream FCode

Feature CodeFeature DescriptionFeature Definition
46100Submerged Stream (no attributes)The original river course inundated by an impounded water body. These are mostly used in drowned river systems like the Tennessee Valley Authority (TVA) lakes. May be a named feature.

SwampMarsh FCode

Feature CodeFeature DescriptionFeature Definition
46600SwampMarsh (Hydrographic Category = null)A noncultivated, vegetated area that is inundated or saturated for a significant part of the year. The vegetation is adapted for life in saturated soil conditions.
46601SwampMarsh (Hydrographic Category = Intermittent)A noncultivated, vegetated area that is inundated or saturated for a significant part of the year. The vegetation is adapted for life in saturated soil conditions. Contains water for only part of the year, but more than just after rainstorms and at snowmelt.
46602SwampMarsh (Hydrographic Category = Perennial)A noncultivated, vegetated area that is inundated or saturated for a significant part of the year. The vegetation is adapted for life in saturated soil conditions. Contains water throughout the year, except for infrequent periods of severe drought.

Tunnel FCode

Feature CodeFeature DescriptionFeature Definition
47800Tunnel (no attributes)An underground or underwater passage that carries water bearing features such as CanalDitch or Pipeline. May be a named feature.

Underground Conduit FCode

Feature CodeFeature DescriptionFeature Definition
42000Underground Conduit (Positional Accuracy = null)A set of naturally occurring subsurface drainage channels formed from the dissolution of soluble rocks in Karst terrain or in terrain similar to karst but formed in nonsoluble rocks, as by melting of permafrost or ground ice, collapse after mining, and by outflow of liquid lava from beneath its solidified crust. The accuracy within which the feature may be confidently positioned is unknown.
42001Underground Conduit (Positional Accuracy = Definite)A set of naturally occurring subsurface drainage channels formed from the dissolution of soluble rocks in Karst terrain or in terrain similar to karst but formed in nonsoluble rocks, as by melting of permafrost or ground ice, collapse after mining, and by outflow of liquid lava from beneath its solidified crust. The accuracy within which the feature may be confidently positioned is definite (conditions permit the feature to be confidently positioned. Horizontal data are confidently positioned within 0.02" (40 feet at 1:24,000 scale), at map scale, of true ground position).
42002Underground Conduit (Positional Accuracy = Indefinite)A set of naturally occurring subsurface drainage channels formed from the dissolution of soluble rocks in Karst terrain or in terrain similar to karst but formed in nonsoluble rocks, as by melting of permafrost or ground ice, collapse after mining, and by outflow of liquid lava from beneath its solidified crust. The accuracy within which the feature may be confidently positioned is indefinite (conditions prevent the feature from being confidently positioned. Horizontal data cannot be confidently positioned within 0.02", at map scale, of the true ground position).
42003Underground Conduit (Positional Accuracy = Approximate)A set of naturally occurring subsurface drainage channels formed from the dissolution of soluble rocks in Karst terrain or in terrain similar to karst but formed in nonsoluble rocks, as by melting of permafrost or ground ice, collapse after mining, and by outflow of liquid lava from beneath its solidified crust. The accuracy within which the feature may be confidently positioned is approximate (conditions permit the feature to be confidently positioned between 0.02" and 0.1", at map scale, of its true ground position.).

Wall FCode

Feature CodeFeature DescriptionFeature Definition
48300Wall (no attributes)An upright structure of masonry, wood, plaster, or other building material serving to separate land from water with no additional structures present. If other associated structures, such as DamWeir, are present use Nonearthen Shore. Not a named feature.

Wash FCode

Feature CodeFeature DescriptionFeature Definition
48400Wash (no attributes)The usually dry portion of a stream bed that contains water only during or after a local rainstorm or heavy snowmelt. May be a named feature.

Water IntakeOutflow FCode

Feature CodeFeature DescriptionFeature Definition
48500Water Intake/Outflow (no attributes)A structure through which water enters or exits through a divergence structure. Water Intake/Outflow also exists as an NHDPoint. Not a named feature.

Waterfall FCode

Feature CodeFeature DescriptionFeature Definition
48700Waterfall (no attributes)A vertical or near vertical descent of water over a step or ledge in the bed of a river. Waterfall also exists as an NHDPoint. May be a named feature.

Well FCode

Feature CodeFeature DescriptionFeature Definition
48800Well (no attributes)A pit or hole dug or bored into the earth for the extraction of oil, water, other fluids, or gases. May be a named feature.




NON-FCODE DOMAINS

"Enabled" attribute values

CodeDescriptionDefinition
0Not enabledNot enabled, shown as False in the geodatabase.
1EnabledEnabled, shown as True in the geodatabase.

Area Event Type Domain

CodeDescriptionDefinition

ElevationRange

CodeDescriptionDefinition
MaxValue9000
MinValue-400

HUType Domain

CodeDescriptionDefinition
CClosed basinA drainage area where all surface flow is internal (100 percent noncontributing); no overland flow leaves the hydrologic unit through the outlet point.
DIndeterminate Areas of complex terrain or hydrology where flow within and connections between hydrologic units are uncertain or have potential to change. New for WBD 2.3 Schema.
FFrontalAn area along the coastline of a lake, ocean, bay, etc., that has more than one outlet. These hydrologic units are predominantly land with some water areas at or near the outlet(s).
IIslandAn area that is one or more islands, which includes surrounding water.
MMultiple outletAn area that has more than one natural outlet, such as an outlet located on a stream that has multiple channels (for example, braided streams, deltas or alluvial fans). Multiple Outlet does not include frontal or water hydrologic units, hydrologic units with artificial interbasin transfers, drainage outlets through karst or groundwater flow, or outlets that cross a stream with an island. Use this code only in rare instances.
SStandardAn area with drainage flowing to a single outlet point, excluding noncontributing areas. Some examples include “true,” “classic,” “composite,” and “remnant” hydrologic units.
UUrbanDrainage areas in urban areas that are altered by engineered surface and subsurface drainage systems. New for WBD 2.3 Schema.
WWaterAn area that is predominantly water with adjacent land areas; for example, a lake, estuary, or harbor.

HydroFlowDirections

CodeDescriptionDefinition
0UninitializedDirection of flow relative to coordinate order is uninitialized.
1WithDigitizedDirection of flow relative to coordinate order is witih digitized.

LandSea Domain

CodeDescriptionDefinition
0Estuary
1Land
2Sea

Line Event Type

CodeDescriptionDefinition

MainPath

CodeDescriptionDefinition
0UnspecifiedUnspecified
1Confluence MainLocation where separate streams join the main path.
2Divergence MainLocation where the main path diverges into separate streams.
3Both Confluence Main and Divergence MainLocation where streams both converge and diverge from main path.

NoYesDomain

CodeDescriptionDefinition
0NoNo
1YesYes

Point Event Type

CodeDescriptionDefinition
1Gaging StationThe entity in the event is a gaging station.
2DamThe entity in the event is a dam.
3Divergence Structure = GeneralThe entity in the event is a general divergence structure.
4Divergence Structure = WithdrawingThe entity in the event is a withdrawing divergence structure.
5Divergence Structure = ContributingThe entity in the event is a contributing divergence structure.
57001Streamgage; Status=Active; Record=ContinuousA structure used to measure the characteristics of a hydrographic feature. Gages are usually captured on the flowline, not necessarily on the physical location of the monitoring station. Site is active if: has collected time-series data within the last 183 days, or has collected discrete data within 397 days. Where data collection is continuous, data may be available in real-time, as individual observations, or as daily summaries, and data are collected on a regularly scheduled basis.
57002Streamgage Status=Active; Record=PartialStructure used to measure the characteristics of a hydrographic feature. Gages are usually captured on the flowline and not necessarily on the physical location of the monitoring station. Considered active if: has collected time-series data within the last 183 days, or has collected discrete data within 397 days. A partial-record station is a site where limited water-quality data are collected systematically over a period of years. Frequency of sampling is usually less than quarterly.
57003Streamgage Status=InactiveA structure used to measure the characteristics of a hydrographic feature. Gages are usually captured on the flowline and not necessarily on the physical location of the monitoring station. Considered active if: has collected time-series data within the last 183 days, or has collected discrete data within 397 days. If it does not meet these criteria, it is considered inactive.
57004Water Quality StationA point on the surface water network where a water sample is measured for water quality characteristics.
57100DamA barrier constructed to hold back water and raise its level, the resulting reservoir being used in the generation of electricity or as a water supply.
57201Flow Alteration=AdditionA point on the NHD surface water network where water is added to the network, typically through a conveyance such as a CanalDitch or pipeline.
57202Flow Alteration=Removal A point on the NHD surface water network where water is removed from the network, typically through a conveyance such as a CanalDitch or pipeline. 
57203Flow Alteration UnknownA point on the NHD surface water network where water is either removed or added to the network, typically through a conveyance such as a CanalDitch or pipeline.  
57300Hydrologic Unit OutletThe pour point of a watershed boundary dataset hydrologic unit.
6Water Quality StationThe entity in the event is a water quality station.

PurposeCode Domain

CodeDescriptionDefinition
ACCoastline from adj VPU
AIInflow connecting feature from upstream VPU
AOOutflow flowlines to elevation clip boundary
AUAdded feature from adjacent VPU (upstream)
DCDigitized connector flowline
DODigitized outflow path
OCNHDWaterbody sea, bay, estuary
SCNHDWaterbody closed lake
SDTopographic depression
SENetwork End
SHHUC12 polygon min point or centroid
SKKarst sinkhole
SNBurnLineEvent non-spatial connection
SOOther Sink
SPNHDWaterbody playa
UFUnused feature (FCode or by feature)
WBNHDWaterbody (other)

Resolution

CodeDescriptionDefinition
1Local1:12,000 source resolution.
2High1:24,000 - 12,000 source resolution.
3Medium1:100,000 source resolution.

StatusFlag Domain

CodeDescriptionDefinition
AAdd
CChange
DDelete
NNot Set

VisibilityFilter

CodeDescriptionDefinition
0UnspecifiedObjects with a Visibility Attribute = 0 have not been evaluated
100000Approximately 1:100,000 or Larger ScaleObjects with a Visibility Attribute = 100000 indicates that it is not appropriate to use the object at scales smaller than approximately 1:100,000 (i.e. object should be pruned at scales smaller than 1:100,000)
1000000Approximately 1:1,000,000 or Larger Objects with a Visibility Attribute = 1000000 indicates that it is not appropriate to use the object at scales smaller than approximately 1:1,000,000 (i.e. object should be pruned at scales smaller than 1:1,000,000)
12500Approximately 1:12,500 or Larger ScaleObjects with a Visibility Attribute = 12500 indicates that it is not appropriate to use the object at scales smaller than approximately 1:12,500 (i.e. object should be pruned at scales smaller than 1:12,500)
150000Approximately 1:150,000 or Larger ScaleObjects with a Visibility Attribute = 150000 indicates that it is not appropriate to use the object at scales smaller than approximately 1:150,000 (i.e. object should be pruned at scales smaller than 1:150,000)
2000000Approximately 1:2,000,000 or Larger ScaleObjects with a Visibility Attribute = 2000000 indicates that it is not appropriate to use the object at scales smaller than approximately 1:2,000,000 (i.e. object should be pruned at scales smaller than 1:2,000,000)
24000Approximately 1:24,000 or Larger ScaleObjects with a Visibility Attribute = 24000 indicates that it is not appropriate to use the object at scales smaller than approximately 1:24,000 (i.e. object should be pruned at scales smaller than 1:24,000)
250000Approximately 1:250,000 or Larger ScaleObjects with a Visibility Attribute = 250000 indicates that it is not appropriate to use the object at scales smaller than approximately 1:250,000 (i.e. object should be pruned at scales smaller than 1:250,000)
4800Approximately 1:4,800 or Larger ScaleObjects with a Visibility Attribute = 4800 indicates that it is not appropriate to use the object at scales smaller than approximately 1:4,800 (i.e. object should be pruned at scales smaller than 1:4,800)
50000Approximately 1:50,000 or Larger ScaleObjects with a Visibility Attribute = 50000 indicates that it is not appropriate to use the object at scales smaller than approximately 50,000 (i.e. object should be pruned at scales smaller than 1:50,000)
500000Approximately 1:500,000 or Larger ScaleObjects with a Visibility Attribute = 500000 indicates that it is not appropriate to use the object at scales smaller than approximately 1:500,000 (i.e. object should be pruned at scales smaller than 1:500,000)
5000000Approximately 1:5,000,000 or Larger Scale Objects with a Visibility Attribute = 5000000 indicates that it is not appropriate to use the object at scales smaller than approximately 1:5,000,000 (i.e. object should be pruned at scales smaller than 5,000,000)