# NHDMetadata

ProcessDescription:
Create high-resolution NHD from USGS DLG data. DLG files were  converted to ArcInfo coverages and projected to the New  Hampshire State Plane coordinate system (NHSP NAD83 Feet).  Having the data in NHSP allowed for the draping of the vector  data with the State of New Hampshire's projected Digital  Raster Graphic Images (DRGs, source: USGS), when needed for  feature verification/connection. The DLG coverages were  edgematched using a 40 foot snapping tolerance.  Features  outside the tolerance were not moved; instead, a feature of  type connector was added to join the features. DLG feature  coding was visually verified using hardcopy plots. Coverages  were then paneled into one coverage and arcs within 40 feet  of each other along the neatline were again snapped together  if the feature types were the same.  Next, the 11-digit  Hydrologic Unit Code (HUC) boundary was used to extract  features from the paneled coverage that fell within the  boundary. Next, arcs from the extracted coverage were grouped  in order to examine the connectivity of the data set for  flow determination. In some cases it was necessary to correct  digitizing errors.  Using contour lines from the New Hampshire  DRGs, lines called connectors were added to join features that  were deemed to have flow between each other.  All arcs were  directed downstream and the nodes were prepared to help create artificial paths through 2-D waterbodies and complete the flow through the hydrography network.  The artificial path coverage was combined with the single line stream network to create the drainage network.  The drainage network was grouped again,  and each group was directed downstream.  The data was then  appended to conform to the 8-digit CU boundaries.  Feature codes  (fcodes)were assigned to network and 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. Names for the 24K drainage network were  interactively transferred from the vector GNIS coverage.  Additional GNIS names for waterbody features were also added.

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 the 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(DOQ's). 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 topographicquadrangle 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:
FGDC Content Standards For Digital Geospatial Metadata

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:
Mid-Continent Mapping Center - 1400 Independence Road


ProcessDescription:
Create high-resolution NHD from the Maine Office of GIS hydrography  data, which has historically been stored and managed by 1:24,000-scale  quadrangles and ArcInfo Librarian.  ArcInfo Librarian was used to  extract the hydrography library layers (streams, ponds, rivers, and  coast), append the tiles together, and merge like polygon features  together.  The 8-digit Hydrologic Unit Code (HUC) boundary was  obtained from the State NRCS office to clip features from the paneled  coverage that fell partially or entirely within the boundary.  Where  necessary, the HUC boundary was slightly modified to completely  include or exclude features that incorrectly overlapped the boundary.   Substantial alterations to the HUC boundary were confirmed on the  topographic maps and with NRCS.  DRGCLIPs and MEDOQs were used as a  reference to revise the current hydrography data by edge matching  between quadrangles and digitizing photorevised features.  Features  were modified to the DRGCLIPs and MEDOQs only where compelling evidence  of change existed.  The National Wetlands Inventory (NWI) was used to  confirm connectors through wetlands with none of the existing NWI  linework being incorporated into the NHD data.  Arcs from the  extracted coverages were grouped in order to examine the connectivity  of the dataset for flow determination.  In some cases it was necessary  to correct digitizing errors.  Using available evidence or cartographic  judgement, lines called connectors were added to join features that  were deemed to have flow between each other.  All arcs were directed  downstream and the nodes were prepared to help create artificial paths  through 2-D waterbodies to complete the flow through the hydrography  network.  The artificial path coverage was combined with the single  line stream network to create the drainage network.  The drainage  network was grouped again, and each group was directed downstream.   Feature codes (fcodes) were assigned to landmark, network, waterbody  features through a crosswalk that converts DLG-3 attributes to fcodes,  where an fcode is a five digit integer that encodes a set of feature  type characteristics.  Reach codes and associated attributes were  conflated from the 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 subbasin.  Additional Geographic Names that exist  in the Geographic Names Information System (GNIS) were added to  reaches in the 24K dataset.  Names for the 24K drainage network were  interactively transferred from the vector GNIS coverage.  Additional  GNIS names for point and waterbody features were also added.

AttributeAccuracyreport:
Attribute accuracy was tested by visual comparison of the source or symbolized display of digital files.  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 June 2002  extract from the Geographic Names Information System (GNIS).  The  entry and identifier for the names match those in GNIS.  The  association of each name to reaches has been interactively checked  against the GNIS 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 amoung areas do not exist.  All areas close.  Spatial topology meets the Maine Office of GIS Data  Standards.  Label errors and node errors have been resolved.   Spatial topology is clean and free of errors.  The coverage was  built with polygon topology.

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  datasets 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 type of  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:
FGDC Content Standard for Digital Geospatial Metadata, ver.2

DataSetCredit:
U.S. Geological Survey, in cooperation with U.S. Environmental  Protection Agency and Maine Office of Geographic Information  Systems


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.


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


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.

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.

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

Address:
U. S. Geological Survey,National Geospatial Technical Operations Center, 1400 Indepence Roaf


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


ProcessDescription:
Maintenance of known errors to the NHD using 2009 NAIP imagery and 2006 NHDOT 1 foot orthoimagery. Maintenance includes changes to flowline and waterbody geomety and attribution, including but not limited to changing connectors to stream/river where appropriate, and adding in flowlines from internal databases. Also updated 2D river features to reflect bankfull extent as defined by the limit of perenial vegetation.

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


# NHDSourceCitation

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


SourceCurrentnessReference:
Date the revision process step was completed


Originator:
U.S. Geological Survey (USGS), in cooperation with the Natural Resources Conservation Service (NRCS),  and the New Hampshire Department of Environmental Services.


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

SourceContribution:
Reach codes and flow direction attributes.


Originator:
U.S. Geological Survey (USGS), in cooperation with the  Natural Resources Conservation Service (NRCS) and the  Maine Office of GIS (MEGIS)


Title:
Geographic Names Information System Oracle Database

SourceContribution:
Names for reaches and areal water bodies


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

SourceContribution:
Reach codes and flow direction attributes


SourceContribution:
Names for reaches and areal water bodies.


# 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)


