# NHDMetadata

ProcessDescription:
Replaced branched and disjoint (disconnected) reaches with linear reaches in NHDFlowline.  This change occurred during the conversion to the geodatabase model.  Each NHDFlowline that was part of a branched or disjoint reach was assigned to a new reach.  The ComID of the NHDFlowline was unchanged   The change information from the old reach to the new reach was captured in the NHDReachCrossReference table.  Each new reach has M values assigned from 0 to 100.


ProcessDescription:
Merged and/or split area features (NHDWaterbody, NHDArea, region.wb, region.lm) and updated associated artificial path WBAreaComID (wb_com_id) values.  This change occurred during the conversion to the geodatabase model.  If adjacent or overlapping area features had identical classifications, including ReachCode where applicable, the features were merged.  If an area feature exceeded 100 sq. km. (25 sq. km. for canal/ditch, stream/river, or submerged stream) and crossed a subbasin boundary, the feature was split at the subbasin boundary.  If any sliver polygons of a size of less than 5 sq. km. adjoined the split features, the slivers were merged back into the larger area feature.  Merged or split area features were assigned a new ComID.


ProcessDescription:
Updated WBAreaComID (WB_COM_ID) on NHDFlowline (route.drain) where the associated area features were assigned new ComIDs from merge or split during the conversion to geodatabase.


ProcessDescription:
Create high-resolution NHD from USGS/WRD hydrography data.  This process started with the acquistion of two sources of  vectors provided by USGS NMD.  Existing 1:24,000-scale USGS  Digital Line Graph data was available.  Feature code  attributes present in the DLG major and minor codes  were used to populate a temporary working coding scheme used by WRD.  For the remaining quadrangle files, NMD  provided unattributed vector data, from scanned Mylar 1:24,000-scale hydrography separates.  The quads were  then converted into ArcInfo coverages and projected into  the Vermont State Plane coordinate system (VTSP NAD83 meters). Having the data in VTSP allowed for the draping of the vector  data with the State of Vermont's projected Digital Raster  Graphic Images (source: USGS).  Quadrangle-based hydro  coverages were then edge-matched, where arcs 12 meters of  each other along the neatline were snapped together if the feature types were the same.  Next, the 12-digit Hydrologic  Unit Code (HUC) boundary was obtained from the State's NRCS  office.  The 12-digit HUC coverage was manually interpreted  from USGS, 1:24,000-scale, 7.5' topographic maps.  The HUC  boundary was used to break up the basin into tiles based on the 12-digit HUCs which defined the basin boundary.   Paneling the hydrography according to the 12-digit HUCs  allowed for systematic processing using a logical approach  and manageable format.  Where necessary, the HUC boundary  was slightly modified or the hydrography was corrected  to completely include or exclude features that  incorrectly overlapped the HUC boundaries.  Substantial  alterations to the HUC boundary were confirmed on the  topographic maps (DRGs).  Using available evidence or  cartographic judgement, lines called connectors were added  to join features that were deemed to have flow between each  other.  Artificial paths were digitized on-screen, manually,  through 2-D waterbodies using the waterbody geometry to  digitize a centerline through the features.  Next, arcs from the extracted coverage were grouped in order to examine the  connectivity of the data set for flow determination.  In some  cases it was necessary to correct digitizing errors.  Next,  feature code attributes were assigned for all arcs which did not already have coding assigned.  Feature codes were assigned using WRD's coding scheme.  Next, arcs from the extracted  coverages were grouped in order to examine the connectivity  of the data set for flow determination.  The individual hydro files were then appended back together into one single  hydrography coverage.  All arcs fnode to tnode topology were  corrected to insure all arcs in the network pointed in a  downstream direction.  Last, all WRD feature codes were  transferred over into the NHD fcode scheme, and projected  into the NHD common projection (ALBERS NAD83, meters).  Feature codes (fcodes) were assigned to landmark, network,  waterbody features through a crosswalk that converts DLG-3  attributes to fcodes, where an fcode is a five digit integer  that encodes a set of feature type characteristics.  Reach  codes and associated attributes were conflated from the 100K NHD data to the 24K drainage network and 2-D waterbodies. Several checks were performed to validate the reach transfer process.  Any reach codes that could not be maintained are  tracked in the Reach Cross Reference table.  New reaches  that do not exist in the 100K data were defined according  to reach delineation rules  (See http://nhd.usgs.gov/chapter1/index.html).  New waterbody  reaches were assigned to 2-D lake/pond and reservoir features  that do not exist in the 100K NHD.  New reaches were assigned reach code values that are sequentially ordered to 2-D and  then 1-D reaches.  New 24K reach codes are larger than any  existing 100K reach code in the associated Catalog Unit.  Additional Geographic Names that exist in the Geographic Names  Information System (GNIS) were added to reaches in the 24K  dataset.  Nam

AttributeAccuracyreport:
The accuracy of the attributes of the source Digital Line  Graph data is estimated to be 98.5 percent.  One or more of  the following methods were used to test attribute accuracy:  manual comparison of the source with hardcopy plots;  symbolized display of the digital line graph on an  interactive computer graphic system; selected attributes  that could not be visually verified on plots or on screen  were interactively queried and verified on screen.  In  addition, software validated feature types and  characteristics against a master set of types and  characteristics, checked that combinations of types and  characteristics were valid, and that types and  characteristics were valid for the delineation of the  feature.  Feature types, characteristics, and other  attributes conform to the Standards for National  Hydrography Dataset - High Resolution (USGS, 1999) as of  the date they were loaded into the database.  All names  on the 1:24,000-scale reaches were validated against a  April 1999 extract from the Geographic Names Information  System.  The entry and identifier for the names match those  in the Geographic Names Information System.  The association  of each name to reaches has been interactively checked  against an April 1999 Geographic Names Information System  names extract, however, operator error could in some cases  apply a name to a wrong reach.

LogicalConsistencyReport:
Points, nodes, lines, and areas conform to topological rules.   Lines intersect only at nodes, and all nodes anchor the ends  of lines.  Lines do not overshoot or undershoot other lines  where they are supposed to meet.  There are no duplicate lines.  Lines bound areas and lines identify the areas to the left and  right of the lines.  Gaps and overlaps among areas do not  exist.  All areas close.

CompletenessReport:
The completeness of the data reflects the published USGS  topographic quadrangle usually, supplemented by Digital  Orthophoto Quadrangles (DOQs).  Features found on the ground may  have been eliminated or generalized on the source map because  of scale and legibility constraints.  In general, streams longer  than one mile (approximately 1.6 kilometers) were collected.  Most streams that flow from a lake were collected regardless  of their length.  Only definite channels were collected so  not all swamp/marsh features have stream/rivers delineated  through them.  Lake/ponds 100 feet or greater in the shortest  axis were collected.  Note, however, that these general rules  were applied unevenly among maps during compilation.  Transport reaches are defined on nearly all features of type  stream/river, canal/ditch, artificial path, and connector.   Waterbody reaches are defined on all lake/pond features.  Detailed  capture conditions are provided for every feature type in the  Standards for National Hydrography Dataset - High Resolution  (USGS, 1999), available online through  http://mapping.usgs.gov/standards/.

HorizPositionalAccuracyReport:
Statements of horizontal positional accuracy are based on  accuracy statements made for U.S. Geological Survey topographic  quadrangle maps.  These maps were compiled to meet National Map  Accuracy Standards.  For horizontal accuracy, this standard is  met if at least 90 percent of points tested are within 0.02  inch (at map scale) of the true position.  Additional offsets  to positions may have been introduced where feature density is  high to improve the legibility of map symbols.  In addition, the  digitizing of maps is estimated to contain a horizontal  positional error of less than or equal to 0.003 inch standard  error (at map scale) in the two component directions relative  to the source maps.  Visual comparison between the map graphic  (including digital scans of the graphic) and plots or digital  displays of points, lines, and areas, is used as control to  assess the positional accuracy of digital data.  Digital map  elements along the adjoining edges of data sets are aligned if  they are within a 0.02 inch tolerance (at map scale).  Features  with like dimensionality (for example, features that all are  delineated with lines), with or without like characteristics,  that are within the tolerance are aligned by moving the  features equally to a common point.  Features outside the  tolerance are not moved; instead, a feature of type connector  is added to join the features.

VertPositionalAccuracyReport:
Statements of vertical positional accuracy for elevation of  water surfaces are based on accuracy statements made for  U.S. Geological Survey topographic quadrangle maps.  These  maps were compiled to meet National Map Accuracy Standards.   For vertical accuracy, this standard is met if at least 90  percent of well-defined points tested are within one-half  contour interval of the correct value.  Elevations of water  surface printed on the published map meet this standard;  the contour intervals of the maps vary.  These elevations  were transcribed into the digital data; the accuracy of  this transcription was checked by visual comparison between  the data and the map.

MetadataStandardName:
Content Standard For Digital Geospatial Metadata, ver.2

DataSetCredit:
U.S. Geological Survey in cooperation with U. S. Environmental Protection Agency.


ProcessDescription:
Create high-resolution NHD from USGS/WRD hydrography data.  This process started with the acquisition of two sources of  vectors provided by USGS NMD.  Existing 1:24,000-scale USGS  Digital Line Graph data was available.  Feature code attributes  present in the DLG major and minor codes were used to populate a  temporary working coding scheme used by WRD.  For the remaining  quadrangle files, NMD provided unattributed vector data, from  scanned Mylar 1:24,000-scale hydrography separates.  The quads  were then converted into ArcInfo coverages and projected into  the Vermont State Plane coordinate system (VTSP NAD83 meters).   Having the data in VTSP allowed for the draping of the vector  data with the State of Vermont's projected Digital Raster Graphic  Images (source: USGS).  Quadrangle-based hydro coverages were  then edge-matched, where arcs 12 meters of each other along the  neatline were snapped together if the feature types were the same.   Next, the 12-digit Hydrologic Unit Code (HUC) boundary was  obtained from the State's NRCS office.  The 12-digit HUC coverage  was manually interpreted from USGS, 1:24,000-scale, 7.5'  topographic maps.  The HUC boundary was used to break up the basin  into tiles based on the 12-digit HUCs which defined the basin  boundary.  Paneling the hydrography according to the 12-digit HUCs  allowed for systematic processing using a logical approach and  manageable format.  Where necessary, the HUC boundary was slightly  modified or the hydrography was corrected to completely include or  exclude features that incorrectly overlapped the HUC boundaries.   Substantial alterations to the HUC boundary were confirmed on the  topographic maps (DRGs).  Using available evidence or cartographic  judgement, lines called connectors were added to join features  that were deemed to have flow between each other.  Artificial  paths were digitized on-screen, manually, through 2-D waterbodies  using the waterbody geometry to digitize a centerline through the  features.  Next, arcs from the extracted coverage were grouped in  order to examine the connectivity of the data set for flow  determination.  In some cases it was necessary to correct  digitizing errors.  Next, feature code attributes were assigned  for all arcs which did not already have coding assigned.  Feature  codes were assigned using WRD's coding scheme.  Next, arcs from  the extracted coverages were grouped in order to examine the  connectivity of the data set for flow determination.  The  individual hydro files were then appended back together into one  single hydrography coverage.  All arcs fnode to tnode topology  were corrected to insure all arcs in the network pointed in a  downstream direction.  Last, all WRD feature codes were  transferred over into the NHD fcode scheme, and projected into  the NHD common projection (ALBERS NAD83, meters).  Feature codes  (fcodes) were assigned to landmark, network, waterbody features  through a crosswalk that converts DLG-3 attributes to fcodes,  where an fcode is a five digit integer that encodes a set of  feature type characteristics.  Reach codes and associated  attributes were conflated from the 100K NHD data to the 24K  drainage network and 2-D waterbodies.  Several checks were  performed to validate the reach transfer process.  Any reach  codes that could not be maintained are tracked in the Reach  Cross Reference table.  New reaches that do not exist in the  100K data were defined according to reach delineation rules  (See http://nhd.usgs.gov/chapter1/index.html).  New waterbody  reaches were assigned to 2-D lake/pond and reservoir features  that do not exist in the 100K NHD.  New reaches were assigned  reach code values that are sequentially ordered to 2-D and then  1-D reaches.  New 24K reach codes are larger than any existing  100K reach code in the associated Catalog Unit.  Additional  Geographic Names that exist in the Geographic Names Information  System (GNIS) were added to reaches in the 24K d

DataSetCredit:
U.S. Geological Survey in cooperation with U. S. Environmental  Protection Agency


ProcessDescription:
Added flow relationships between subbasins and other updates as appropriate.


ProcessDescription:
1:100,000 scale medium-resolution stream gage shapefiles obtained from the U.S. Geological Survey Nation Water Information System and 1:24,000 scale high-resolution watercourse digital data sets collected by the U.S. Geological Survey, National Geospatial Technical Operations Centers (NGTOC), were used to linear reference the medium resolution 0d stream gages to the corresponding high-resolution watercourse geometry.  Quality Assurance was preformed to guarantee that each gage was properly indexed to the watercourse geometry and that the correct spatial address and location on the network were obtained.  The position of the high-resolution gages was not further enhanced based on 1:24,000 scale sources such as DRGs or DOQs.


ProcessDescription:
Create high-resolution NHD Dam features and events from the National Inventory of Dams by snapping NID position to the appropriate position on the appropriate NHDFlowline and obtaining the network address.  Since dams are located on the network, they may be offset from the actual physical position.  Dams that cannot be logically associated with a NHDFlowline are not included.  Dams under a size threshold of 2,400 acre-feet normal storage capacity are generally not included

DataSetCredit:
U.S. Geological Survey, National Geospatial Technical Operations Center

Address:
U.S. Geological Survey, National Technical Operations Center, P.O. Box 25046


ProcessDescription:
Maintenance Lite 1D review. Evaluate and correct network connectivity and flow direction as needed. Review and edit gapped GNIS Name and IDs and branched or gapped ReachCodes. Repair overlapping flowline features.

DataSetCredit:
U.S. Geological Survey in cooperation with U. S. Environmental Protection Agency, Complex Systems Research Center at the University of New Hampshire, and New Hampshire Department of Environmental Services.


Address:
U.S. Geological Survey, National Geospatial Technical Operations Center, P.O. Box 25046


ProcessDescription:
Update GNIS ids and names to match the current GNIS ids/names.


ProcessDescription:
Reach codes migrated to match new Watershed Boundary Dataset (WBD) boundaries, which are different from the 250 HUC boundaries used previously to derive reach codes.

MetadataStandardName:
FGDC Content Standards For Digital Geospatial Metadata

DataSetCredit:
U.S. Geological Survey National Geospatial Technical Operations Center (USGS\NGTOC)


ProcessDescription:
NHD High Resolution Maintenance Lite II by Sub Region.  Procedures include the following: Topology is checked for:  NHDWaterbodys must not overlap; NHDWaterbody must not overlap NHDArea; and NHDAreas must not overlap. Check all reaches to ensure that they have MValues (measures). Remove branched GNIS names. Check entire extent of GNIS name for gaps. Check all WBAreaComIDs and correct or add as necessary. Check all coastlines (coincident with 2D features) and correct as necessary. Extract transactional updates (XML) from updated personal geodatabase and load updates into original personal geodatabase for final transaction review. Re-check data integrity based on previous Sub Region Maintenance Lite.

Address:
U.S. Geological Survey, National Geospatial Technical Operations Center, 1400 Independence Road


ProcessDescription:
Edit stream gage locations using http://waterdata.usgs.gov/nwis/nwisman/?site_no= information.


ProcessDescription:
Updated major areal (2-D) features to match current 2008 NAIP imagery. Added lake/ponds 500,000 sq meters or larger. Water surface elevations are not collected on new lake/ponds.  The shoreline for these lake/ponds is date of photography. Modified position of lake/ponds; greater than 1.0 sq km, that do not have a value for elevation in the data, if the shorelines were off by more than 500 ft.  Lake/ponds that have controlled water levels, indicated in the data by a value for “elevation” and “stage”, are not modified.  The elevation represents and average water level for the lake/pond and that elevation is maintained as the most common position of the shoreline over the years. Realigned areal (2-D) stream/rivers; greater than 100 ft wide, when the position of the banks had moved more than 1000 ft.  These areal stream/rivers were corrected to within 200 ft of the image.  If necessary, artificial paths and/or 1-D stream/rivers that were related to or in proximity to the revised 2-D features were edited to maintain flow and conform to the rules of the National Hydrography Dataset (NHD).  These updates were completed by USGS personnel as part of a national update program begun in 2009 to help align prominent features with the orthoimages being used for US Topo product.  After the 2-D features were modified, the standard QA/QC checks were run and any errors were corrected as part of this process.  This QA/QC step generally checks the flow network and topology of the dataset.  The most common edits are for flowlines with incorrect flow direction, invalid WBComIds on Artificial Paths and reach delineation problems.


ProcessDescription:
Maintenance of known errors to the NHD from user reports. Maintenance performed using 2009 NAIP imagery and includes changes to geometries and attibutes including but not limited to: changing connectors to stream/rivers, checking validity of reservoir features, adding in flowlines from internal databases

DataSetCredit:
New Hampshire Department of Environmental Services and New Hampshire Geological Survey


# NHDSourceCitation

Originator:
U.S. Geological Survey in cooperation with the  U.S. Environmental Protection Agency

SourceContribution:
Reach codes and flow direction attributes.


Title:
Geographic Names Information System Oracle Database

SourceContribution:
Names for reaches and areal water bodies.


SourceCurrentnessReference:
Date the revision process step was completed


SourceContribution:
Reach codes and flow direction attributes


SourceContribution:
Names for reaches and areal water bodies


Originator:
The Natural Resources Conservation Service (NRCS) in cooperation with the University of Vermont  Spatial Analysis Lab (UVM)


SourceContribution:
DRG, USGS topo, NED, DEM, DOP, local survey


# NHDFCode

Description:
Underground Conduit: Positional Accuracy = Definite


Description:
Underground Conduit: Positional Accuracy = Indefinite


Description:
Underground Conduit: Positional Accuracy = Approximate


Description:
Pipeline: Pipeline Type = Stormwater; Relationship to Surface = At or Near


Description:
Pipeline: Pipeline Type = Stormwater; Relationship to Surface = Elevated


Description:
Pipeline: Pipeline Type = Stormwater; Relationship to Surface = Underground


Description:
Pipeline: Pipeline Type = Stormwater; Relationship to Surface = Underwater


Description:
Swamp/Marsh: Hydrographic Category = Intermittent


Description:
Reservoir: Reservoir Type = Disposal; Construction Material = Earthen


Description:
Reservoir: Reservoir Type = Disposal; Construction Material = Nonearthen


Description:
Canal/Ditch: Canal/Ditch Type = Aqueduct


Description:
Dam/Weir: Construction Material = Earthen


Description:
Dam/Weir: Construction Material = Nonearthen


Description:
Swamp/Marsh: Hydrographic Category = Perennial


Description:
Lake/Pond: Hydrographic Category = Intermittent


Description:
Lake/Pond: Hydrographic Category = Perennial


Description:
Lake/Pond: Hydrographic Category = Intermittent; Stage = High Water Elevation


Description:
Lake/Pond: Hydrographic Category = Intermittent; Stage = Date of Photography


Description:
Lake/Pond: Hydrographic Category = Perennial; Stage = Average Water Elevation


Description:
Lake/Pond: Hydrographic Category = Perennial; Stage = Normal Pool


Description:
Lake/Pond: Hydrographic Category = Perennial; Stage = Date of Photography


Description:
Lake/Pond: Hydrographic Category = Perennial; Stage = Spillway Elevation


Description:
Inundation Area: Inundation Control Status = Not Controlled


Description:
Inundation Area: Inundation Control Status = Controlled


Description:
Inundation Area: Inundation Control Status = Controlled; Stage = Flood Elevation


Description:
Pipeline: Pipeline Type = Aqueduct; Relationship to Surface = At or Near


Description:
Pipeline: Pipeline Type = Aqueduct; Relationship to Surface = Elevated


Description:
Pipeline: Pipeline Type = Aqueduct; Relationship to Surface = Underground


Description:
Pipeline: Pipeline Type = Aqueduct; Relationship to Surface = Underwater


Description:
Pipeline: Pipeline Type = General Case; Relationship to Surface = At or Near


Description:
Pipeline: Pipeline Type = General Case; Relationship to Surface = Elevated


Description:
Pipeline: Pipeline Type = General Case; Relationship to Surface = Underground


Description:
Pipeline: Pipeline Type = General Case; Relationship to Surface = Underwater


Description:
Pipeline: Pipeline Type = Penstock; Relationship to Surface = At or Near


Description:
Pipeline: Pipeline Type = Penstock; Relationship to Surface = Elevated


Description:
Pipeline: Pipeline Type = Penstock; Relationship to Surface = Underground


Description:
Pipeline: Pipeline Type = Penstock; Relationship to Surface = Underwater


Description:
Reservoir: Reservoir Type = Decorative Pool


Description:
Reservoir: Reservoir Type = Tailings Pond; Construction Material = Earthen


Description:
Reservoir: Reservoir Type = Tailings Pond


Description:
Reservoir: Reservoir Type = Swimming Pool


Description:
Reservoir: Reservoir Type = Cooling Pond


Description:
Reservoir: Reservoir Type = Filtration Pond


Description:
Reservoir: Reservoir Type = Settling Pond


Description:
Reservoir: Reservoir Type = Sewage Treatment Pond


Description:
Reservoir: Reservoir Type = Water Storage; Construction Material = Nonearthen


Description:
Reservoir: Reservoir Type = Water Storage; Construction Material = Earthen; Hydrographic Category = Intermittent


Description:
Reservoir: Reservoir Type = Water Storage; Construction Material = Earthen; Hydrographic Category = Perennial


Description:
Reservoir: Reservoir Type = Water Storage


Description:
Reservoir: Construction Material = Earthen


Description:
Reservoir: Construction Material = Nonearthen


Description:
Reservoir: Reservoir Type = Water Storage; Hydrographic Category = Perennial


Description:
Reservoir: Reservoir Type = Evaporator; Construction Material = Earthen


Description:
Rock: Relationship to Surface = Abovewater


Description:
Rock: Relationship to Surface = Underwater


Description:
Special Use Zone: Special Use Zone Type = Dump Site; Operational Status = Operational


Description:
Special Use Zone: Special Use Zone Type = Dump Site; Operational Status = Abandoned


Description:
Special Use Zone: Special Use Zone Type = Spoil Area; Operational Status = Operational


Description:
Special Use Zone: Special Use Zone Type = Spoil Area; Operational Status = Abandoned


Description:
Stream/River: Hydrographic Category = Intermittent


Description:
Stream/River: Hydrographic Category = Perennial


Description:
Sounding Datum Line: Positional Accuracy = Approximate


Description:
Sounding Datum Line: Positional Accuracy = Definite


Description:
Special Use Zone Limit: Positional Accuracy = Definite


Description:
Special Use Zone Limit: Positional Accuracy = Indefinite


Description:
Stream/River: Hydrographic Category = Ephemeral


Description:
Canal Ditch: Canal Ditch Type = Stormwater


# WBD_HU12

HU_12_Name:
North Fork East Branch Pemigewasset River


# NHDPointEventFC

Source_DataDesc:
National Water Information System (NWIS)


