The National Hydrography Dataset (NHD) High Resolution flowlines were used as a base to provide additional information on the connectivity of the stream network for the hydrographic basins in and around Montana. In addition to the attributes that are published as part of the NHD data, two fields were added to the attribute table to associate streams that do not have a Geographic Names Information System (GNIS) name with the GNIS name and NHD reachcode of the nearest downstream named flowline. The National Hydrography Dataset (NHD) is a feature-based database that interconnects and uniquely identifies the stream segments or reaches that make up the nation's surface water drainage system. NHD data were originally developed at 1:100,000-scale and exists at that scale for the whole country. This high-resolution NHD, generally developed at 1:24,000/1:12,000 scale, adds detail to the original 1:100,000-scale NHD. Local resolution NHD is being developed where partners and data exist. The ...

The National Hydrography Dataset (NHD) is a feature-based database that interconnects and uniquely identifies the stream segments or reaches that make up the nation's surface water drainage system. NHD data was originally developed at 1:100,000-scale and exists at that scale for the whole country. This high-resolution NHD, generally developed at 1:24,000/1:12,000 scale, adds detail to the original 1:100,000-scale NHD. (Data for Alaska, Puerto Rico and the Virgin Islands was developed at high-resolution, not 1:100,000 scale.) Local resolution NHD is being developed where partners and data exist. The NHD contains reach codes for networked features, flow direction, names, and centerline representations for areal water bodies. Reaches are also defined on waterbodies and the approximate shorelines of the Great Lakes, the Atlantic and Pacific Oceans and the Gulf of Mexico. The NHD also incorporates the National Spatial Data Infrastructure framework criteria established by the Federal Geographic Data Committee. For additional information on NHD, go to https://www.usgs.gov/national-hydrography.

This is a simple map that uses map services of the National Hydrography Dataset (NHD) and Watershed Boundaries Dataset (WBD) from The National Map (TNM). Additional layers of the current US Topo and older USA Topo service from Esri are included, but turned off by default. This map is useful as a simple viewer to see the content of the NHD and WBD. In the Search tool pulldown, the “nhd - Flowline - Large Scale” and “nhd - Waterbody - Large Scale” choices search based on ReachCode. The “wbd - 8-digit HU (Subbasin)” and “wbd - 12-digit HU (Subwatershed)” choices search based on the HU code (HUC).

This high-level metadata data document will be supplemented with detailed regional metadata at a later date. The NHDPlusV2 is an integrated suite of application-ready geospatial data sets that incorporate many of the best features of the National Hydrography Dataset (NHD) and the National Elevation Dataset (NED). Interest in estimating stream flow volume and velocity to support pollutant fate-and-transport modeling was the driver behind the joint USEPA and USGS effort to develop the initial NHDPlus, referenced in this document as NHDPlusV1. NHDPlusV1 has been used in a wide variety of applications since its initial release in the fall of 2006. This widespread positive response prompted the multi-agency NHDPlus team to develop NHDPlus Version 2 (NHDPlusV2). The NHDPlusV2 includes a stream network (based on the NHD), improved networking, naming, and "value-added attributes" (VAA's). NHDPlusV2 also includes elevation-derived catchments (drainage areas) produced using a drainage enforcement technique first broadly applied in New England, and thus dubbed "The New-England Method". This technique involves "burning-in" the NHD network and building "walls" using the national Watershed Boundary Dataset (WBD). The hydro-enforced digital elevation model (DEM) is used to produce hydrologic derivatives that agree with the NHD and WBD. An interdisciplinary team from the USGS, USEPA and contractors, has found this method to produce the best quality NHD catchments using an automated process. The VAAs include greatly enhanced capabilities for upstream and downstream navigation, analysis and modeling. Examples include: retrieve all flowlines (predominantly confluence-to-confluence stream segments) and catchments upstream of a given flowline using queries rather than by slower flowline-by-flowline navigation; retrieve flowlines by stream order; select a stream level path sorted in hydrologic order for stream profile mapping, analysis and plotting; and, calculate cumulative catchment attributes using streamlined VAA hydrologic sequencing routing attributes. The VAAs include results from the use of these cumulative routing techniques, including cumulative drainage areas, precipitation, temperature, and runoff distributions. Several of these cumulative attributes are used to estimate mean annual flow and velocity as part of the VAAs. NHDPlusV2 in CONUS contains a snapshot (2012) of the 1:100,000-scale NHD that has been extensively improved over the snapshot used in NHDPlusV1. These updates have not been stored in the central NHD repository at USGS. NHDPlusV2 in the islands is basin on a 2014/2015 snapshot of the 1:24,000 NHD. NHDPlusV2 users may not make updates to the NHD portions of NHDPlusV2 with the intent of sending these updates back to the USGS. Updates to the 1:100,000-scale NHD snapshot should be sent to the USEPA as the primary steward. Updates to the 1:24,000-scale NHD shapshot should be sent to the USGS. Purpose: The geospatial data sets included in NHDPlusV2 are intended to support a variety of water-related applications. They already have been used in an application to develop estimates of mean annual streamflow and velocity for each NHDFlowline feature in the conterminous United States. The results of these analyses are included with the NHDPlusV2 data. NHDPlusV2 serves as the sample frame for the stream and lake surveys conducted by the USEPA under the National Aquatic Resources Surveys program. A water-quality model developed by the U.S. Geological Survey (USGS) called SPARROW (Spatially Referenced Regressions on Watershed Attributes), can utilizes the NHDPlusV2 network functionality to track the downstream transport of nutrients, sediments, or other substances. NHDPlusV2 water bodies and estimates of streamflow and velocity are used in SPARROW to identify reservoir retention and in-stream loss factors. NHDPlusV2 climatic and land surface attributes can be used in SPARROW to identify potential factors in the delivery of nutrients from the land surface to streams. NHDPlusV2 data is also being used in select areas for a USGS Web-based application, called StreamStats. StreamStats provides tools to interactively select any point in the implemented areas, delineate watersheds, and to obtain streamflow and watershed characteristics for the selected point. NHDPlusV2 has been designed to accommodate many users' needs for future applications. NHDPlusV2 provides the framework and tools necessary to customize the behavior of the network relationships as well as building upon the attribute database, for which the user can assign their own data to the network.

The USGS 3D Hydrography Program (3DHP) ArcGIS REST service (3DHP_all) from The National Map is the first of several data services that will be delivered by the 3D Hydrography Program. The 3DHP_all comprises a national network of flowlines, hydrolocations, and water bodies, and will include catchments, drainage areas, and flow network derivatives as they are populated in the future. The 3DHP_all service will provide access to a 3D-enabled geospatial hydrography vector dataset built from 3DHP data and intended to provide the most comprehensive but general rendering of 3DHP data. 3DHP data is derived from elevation-derived hydrography (EDH) Elevation-Derived Hydrography Specifications | U.S. Geological Survey (usgs.gov) where available. Where EDH has not been collected, 3DHP data will be supplemented by data from the National Hydrography Dataset (NHD) National Hydrography Dataset | U.S. Geological Survey (usgs.gov). As further EDH data is collected, the EDH data will replace the NHD data in that data collection area. 3DHP data ingested from EDH sources will include catchments, drainage areas derived from catchments, and flowline network attribute derivatives.Use Constraints: _ None. All data are open and non-proprietary. However, users should be aware that temporal changes may have occurred since this dataset was collected and that some parts of this data may no longer represent actual conditions. Users should not use this data for critical applications without a full awareness of its limitations. This dataset is not intended to be used for site-specific regulatory determinations. Acknowledgment of the U.S. Geological Survey would be appreciated for products derived from these data.For additional information on the 3DHP, go to https://www.usgs.gov/3dhp.See https://apps.nationalmap.gov/help/ for assistance with The National Map viewer, download client, services, or metadata.

The National Hydrography Dataset (NHD) is a feature-based database that interconnects and uniquely identifies the stream segments or reaches that make up the nation's surface water drainage system. NHD data was originally developed at 1:100,000-scale and exists at that scale for the whole country. This high-resolution NHD, generally developed at 1:24,000/1:12,000 scale, adds detail to the original 1:100,000-scale NHD. (Data for Alaska, Puerto Rico and the Virgin Islands was developed at high-resolution, not 1:100,000 scale.) Local resolution NHD is being developed where partners and data exist. The NHD contains reach codes for networked features, flow direction, names, and centerline representations for areal water bodies. Reaches are also defined on waterbodies and the approximate shorelines of the Great Lakes, the Atlantic and Pacific Oceans and the Gulf of Mexico. The NHD also incorporates the National Spatial Data Infrastructure framework criteria established by the Federal Geographic Data Committee. Use the metadata link, http://nhdgeo.usgs.gov/metadata/nhd_high.htm, for additional information.

This U.S. Geological Survey (USGS) data release includes locations for 12,422 USGS streamgages as indexed along the network of streams (flowlines) in NHDPlus Version 2.1 (NHDPlus v2, Moore and Dewald, 2016). The dataset is one of two datasets developed for the Streamgage Watershed InforMation (SWIM) project. This dataset, which is referred to as “SWIM streamgage locations,” was created in support of the second dataset of basin characteristics and disturbance indexes. The streamgages are located in the conterminous United States and have a minimum record length of 20 years of daily streamflow values or at least 20 years of peak flows (USGS National Water Information System (NWIS) database, U.S. Geological Survey, 2016). This dataset has a total of 13,248 streamgages, 826 of which could not be indexed to NHDPlus v2.1. A custom ArcGIS tool was programmed to conduct linear referencing, which moved each point representing a streamgage to intersect with the nearest flowline and calculated the measure along the segment (expressed as a percentage from its downstream end). The tool then performed a series of automated tests to identify potentially inaccurate locations that were, in turn, individually checked. Comments collected during multiple levels of review were retained in raw form to aid future decisions about the accuracy of the streamgage locations along the medium-resolution (1:100,000-scale) NHDPlus stream segments. The results include the unique flowline identifier (COMID) and measure along the flowline, the reach code and measure along its reach (stream feature that consists of one or more flowlines), review notes, plus the latitude and longitude of the stream-referenced location for each streamgage. This designated position along the NHDPlus network may also be referred to as the hydrographic address of the streamgage. References: Falcone, J.A., 2011, GAGES-II: Geospatial Attributes of Gages for Evaluating Streamflow: U.S. Geological Survey dataset, https://doi.org/10.3133/70046617 Moore, R.B., and Dewald, T.G., 2016, The Road to NHDPlus — Advancements in digital stream networks and associated catchments: Journal of the American Water Resources Association, https://doi.org/10.1111/1752-1688.12389 U.S. Geological Survey, 2016, USGS water data for the Nation: U.S. Geological Survey National Water Information System database, accessed October 2016, at https://doi.org/10.5066/F7P55KJN

The National Hydrography Dataset Plus, Version 2 (NHDPlusV2) is an attribute rich, digital hydrologic network for the Conterminous U.S. developed by the U.S. Environmental Protection Agency (EPA) and U.S. Geological Survey (USGS). SPAtially Referenced Regressions On Watershed attributes (SPARROW), is a process-based/statistical model that relies on a digital hydrologic network, like NHDPlusV2, in order to establish spatial relations between monitored contaminant loads, contaminant sources, and other watershed characteristics. The USGS National Water Quality Assessment (NAWQA) project adopted the medium-resolution NHDPlusV2 network as the primary framework supporting SPARROW modeling, and has become a unifying system for reporting hydrologic information. This metadata describes enhancements made to improve the routing capabilities and ancillary hydrologic attributes of NHDPlusV2 to support modeling and other hydrologic analyses. The resulting enhanced network is named E2NHDPlusV2_us.

This data release provides a list of 2,304 water-quality sampling sites indexed to NHDPlus v2.1 flowlines along with the verified ComIDs. ComIDs are the unique identifiers for NHDPlus flowlines and allow the sites to be joined to ancillary and watershed information from other sources published for that purpose. The sites include those assembled for the period 1972-2012 by the U.S. Geological Survey Surface Water Status and Trends project of the National Water-Quality Program (Oelsner and others, 2017, https://doi.org/10.3133/sir20175006), as well as additional water-quality sites assembled for the 2013-2017 time period. Land cover information from the National Land Cover Dataset for the period 2001 through 2016 is also provided for the watershed of each site in this data release.

The National Hydrography Dataset Plus (NHDplus) maps the lakes, ponds, streams, rivers and other surface waters of the United States. Created by the US EPA Office of Water and the US Geological Survey, the NHDPlus provides mean annual and monthly flow estimates for rivers and streams. Additional attributes provide connections between features facilitating complicated analyses. For more information on the NHDPlus dataset see the NHDPlus v2 User Guide.Dataset SummaryPhenomenon Mapped: Surface waters and related features of the United States and associated territories not including Alaska.Geographic Extent: The United States not including Alaska, Puerto Rico, Guam, US Virgin Islands, Marshall Islands, Northern Marianas Islands, Palau, Federated States of Micronesia, and American SamoaProjection: Web Mercator Auxiliary Sphere Visible Scale: Visible at all scales but layer draws best at scales larger than 1:1,000,000Source: EPA and USGSUpdate Frequency: There is new new data since this 2019 version, so no updates planned in the futurePublication Date: March 13, 2019Prior to publication, the NHDPlus network and non-network flowline feature classes were combined into a single flowline layer. Similarly, the NHDPlus Area and Waterbody feature classes were merged under a single schema.Attribute fields were added to the flowline and waterbody layers to simplify symbology and enhance the layer's pop-ups. Fields added include Pop-up Title, Pop-up Subtitle, On or Off Network (flowlines only), Esri Symbology (waterbodies only), and Feature Code Description. All other attributes are from the original NHDPlus dataset. No data values -9999 and -9998 were converted to Null values for many of the flowline fields.What can you do with this layer?Feature layers work throughout the ArcGIS system. Generally your work flow with feature layers will begin in ArcGIS Online or ArcGIS Pro. Below are just a few of the things you can do with a feature service in Online and Pro.ArcGIS OnlineAdd this layer to a map in the map viewer. The layer is limited to scales of approximately 1:1,000,000 or larger but a vector tile layer created from the same data can be used at smaller scales to produce a webmap that displays across the full range of scales. The layer or a map containing it can be used in an application. Change the layer’s transparency and set its visibility rangeOpen the layer’s attribute table and make selections. Selections made in the map or table are reflected in the other. Center on selection allows you to zoom to features selected in the map or table and show selected records allows you to view the selected records in the table.Apply filters. For example you can set a filter to show larger streams and rivers using the mean annual flow attribute or the stream order attribute. Change the layer’s style and symbologyAdd labels and set their propertiesCustomize the pop-upUse as an input to the ArcGIS Online analysis tools. This layer works well as a reference layer with the trace downstream and watershed tools. The buffer tool can be used to draw protective boundaries around streams and the extract data tool can be used to create copies of portions of the data.ArcGIS ProAdd this layer to a 2d or 3d map. Use as an input to geoprocessing. For example, copy features allows you to select then export portions of the data to a new feature class. Change the symbology and the attribute field used to symbolize the dataOpen table and make interactive selections with the mapModify the pop-upsApply Definition Queries to create sub-sets of the layerThis layer is part of the ArcGIS Living Atlas of the World that provides an easy way to explore the landscape layers and many other beautiful and authoritative maps on hundreds of topics.Questions?Please leave a comment below if you have a question about this layer, and we will get back to you as soon as possible.

The NHDPlus Version 1.0 is an integrated suite of application-ready geospatial data sets that incorporate many of the best features of the National Hydrography Dataset (NHD) and the National Elevation Dataset (NED). The NHDPlus includes a stream network (based on the 1:100,000-scale NHD), improved networking, naming, and value-added attributes (VAAs). NHDPlus also includes elevation-derived catchments (drainage areas) produced using a drainage enforcement technique first broadly applied in New England, and thus dubbed The New-England Method. This technique involves burning-in the 1:100,000-scale NHD and when available building walls using the national Watershed Boundary Dataset (WBD). The resulting modified digital elevation model (HydroDEM) is used to produce hydrologic derivatives that agree with the NHD and WBD. An interdisciplinary team from the U. S. Geological Survey (USGS), U.S. Environmental Protection Agency (USEPA), and contractors, over the last two years has found this method to produce the best quality NHD catchments using an automated process.

The VAAs include greatly enhanced capabilities for upstream and downstream navigation, analysis and modeling. Examples include: retrieve all flowlines (predominantly confluence-to-confluence stream segments) and catchments upstream of a given flowline using queries rather than by slower flowline-by-flowline navigation; retrieve flowlines by stream order; subset a stream level path sorted in hydrologic order for stream profile mapping, analysis and plotting; and, calculate cumulative catchment attributes using streamlined VAA hydrologic sequencing routing attributes.

The VAAs include results from the use of these cumulative routing techniques, including cumulative drainage areas, precipitation, temperature, and land cover distributions. Several of these cumulative attributes are used to estimate mean annual flow and velocity as part of the VAAs.

NHDPlus contains a snapshot (2005) of the 1:100,000-scale NHD that has been extensively improved. While these updates will eventually make their way back to the central NHD repository at USGS, this will not have happened prior to distribution of NHDPlus because the update process for the central NHD repository is still in development. Consequently, the NHDPlus will contain some temporary database keys and, as a result, NHDPlus users may not make updates to the NHD portions of NHDPlus with the intent of sending these updates back to the USGS. Once the NHDPlus updates have been posted to the central NHD repository, a fresh copy of the improved data can be downloaded from the central NHD repository and that copy will be usable for data maintenance. Note that the NHDPlus products are tightly integrated and user modifications to the underlying NHD can compromise this synchronization.

The National Hydrography Dataset (NHD) - link to USGS website - is a feature-based database that interconnects and uniquely identifies the stream segments or reaches that make up the nation's surface water drainage system. NHD data was originally developed at 1:100,000 scale and exists at that scale for the whole country. High resolution NHD adds detail to the original 1:100,000-scale NHD. (Data for Alaska, Puerto Rico and the Virgin Islands was developed at high-resolution, not 1:100,000 scale.) Like the 1:100,000-scale NHD, high resolution NHD contains reach codes for networked features and isolated lakes, flow direction, names, stream level, and centerline representations for areal water bodies. Reaches are also defined to represent waterbodies and the approximate shorelines of the Great Lakes, the Atlantic and Pacific Oceans and the Gulf of Mexico. The NHD also incorporates the National Spatial Data Infrastructure framework criteria set out by the Federal Geographic Data Committee.NHD is used with other data themes such as elevation, boundaries, and transportation to produce general reference maps. The NHD is often used by scientists using GIS technology. GIS takes advantage of a rich set of attributes that can be processed to generate specialized information. These analyses are possible because the NHD contains a flow direction network that traces the water downstream or upstream. The NHD also uses an addressing system to link specific information about the water such as discharge rates, water quality, and fish population. Using the basic NHD attributes, flow network, linked information, and other characteristics, it is possible to study cause and affect relationships such as how a source of poor water quality upstream might affect a fish population downstream. The features in the NHD are organized into polygons, lines and points. The polygons most commonly portray waterbodies such as lakes while lines commonly portray streams. The stream lines are broken into shorter segments stretching from confluence-to-confluence. The segments are then linked together to trace the flow of water across the landscape. Flowlines attributed as artificial paths are added inside water bodies to maintain the flow network.

The WA State National Hydrography Dataset (NHD) is the standard hydrography for Washington. NHD Flowline contains linear watercourses representing streams, rivers, canals, ditches, coastline, pipelines, and artificial paths (centerlines through water polygon features such as lakes, estuaries, or double-banked streams). Flowline data for Washington are developed at a resolution of 1:4,800 to 1:24,000. This dataset was extracted and projected into WA State Plane Coordinates South. The coastline in the Puget Sound was updated in 2022 and references the Mean High Water (MHW) datum. Strahler Stream Order has been calculated and added using Esri ArcGIS Pro tools. A trace network was created from simplified flowlines and has also been added. The National Hydrography Dataset (NHD) is a feature-based database that interconnects and uniquely identifies the stream segments or reaches that make up the nation's surface water drainage system. This high-resolution NHD, generally is developed at 1:24,000/1:12,000 scale, but many areas of Washington State have been improved to 1:4800 scale. NHD data was originally developed at 1:100,000-scale and exists at that scale for the whole country. Local resolution NHD is being developed where partners and data exist. The NHD contains reach codes for networked features, flow direction, names, and centerline representations for areal water bodies. Reaches are also defined on waterbodies and the approximate shorelines of the Great Lakes, the Atlantic and Pacific Oceans and the Gulf of Mexico. The NHD also incorporates the National Spatial Data Infrastructure framework criteria established by the Federal Geographic Data Committee. Stream Orders in Washington State range from 1 to 10. The smallest headwater streams are a 1, and the Columbia River is a 10. A detailed data dictionary is available at https://nhd.usgs.gov/userguide.html?url=NHD_User_Guide/Feature_Catalog/NHD_Feature_Catalog.htm

This high-level metadata data document will be supplemented with detailed regional metadata at a later date. The NHDPlusV2 is an integrated suite of application-ready geospatial data sets that incorporate many of the best features of the National Hydrography Dataset (NHD) and the National Elevation Dataset (NED). Interest in estimating stream flow volume and velocity to support pollutant fate-and-transport modeling was the driver behind the joint USEPA and USGS effort to develop the initial NHDPlus, referenced in this document as NHDPlusV1. NHDPlusV1 has been used in a wide variety of applications since its initial release in the fall of 2006. This widespread positive response prompted the multi-agency NHDPlus team to develop NHDPlus Version 2 (NHDPlusV2). The NHDPlusV2 includes a stream network (based on the 1:100,000-scale NHD), improved networking, naming, and "value-added attributes" (VAA's). NHDPlusV2 also includes elevation-derived catchments (drainage areas) produced using a drainage enforcement technique first broadly applied in New England, and thus dubbed "The New-England Method". This technique involves "burning-in" the 1:100,000-scale NHD and building "walls" using the national Watershed Boundary Dataset (WBD). The hydro-enforced digital elevation model (DEM) is used to produce hydrologic derivatives that agree with the NHD and WBD. An interdisciplinary team from the USGS, USEPA and contractors, has found this method to produce the best quality NHD catchments using an automated process. The VAAs include greatly enhanced capabilities for upstream and downstream navigation, analysis and modeling. Examples include: retrieve all flowlines (predominantly confluence-to-confluence stream segments) and catchments upstream of a given flowline using queries rather than by slower flowline-by-flowline navigation; retrieve flowlines by stream order; select a stream level path sorted in hydrologic order for stream profile mapping, analysis and plotting; and, calculate cumulative catchment attributes using streamlined VAA hydrologic sequencing routing attributes. The VAAs include results from the use of these cumulative routing techniques, including cumulative drainage areas, precipitation, temperature, and runoff distributions. Several of these cumulative attributes are used to estimate mean annual flow and velocity as part of the VAAs. NHDPlusV2 contains a snapshot (2012) of the 1:100,000-scale NHD that has been extensively improved over the snapshot used in NHDPlusV1. While these updates will eventually be stored in the central NHD repository at USGS, this will not be accomplished prior to distribution of NHDPlusV2. NHDPlusV2 users may not make updates to the NHD portions of NHDPlusV2 with the intent of sending these updates back to the USGS. Updates to the 1:100,000-scale NHD snapshot in NHDPlusV2 should be sent to the USEPA as the primary steward. Purpose: The geospatial data sets included in NHDPlusV2 are intended to support a variety of water-related applications. They already have been used in an application to develop estimates of mean annual streamflow and velocity for each NHDFlowline feature in the conterminous United States. The results of these analyses are included with the NHDPlusV2 data. NHDPlusV2 serves as the sample frame for the stream and lake surveys conducted by the USEPA under the National Aquatic Resources Surveys program. A water-quality model developed by the U.S. Geological Survey (USGS) called SPARROW (Spatially Referenced Regressions on Watershed Attributes), can utilizes the NHDPlusV2 network functionality to track the downstream transport of nutrients, sediments, or other substances. NHDPlusV2 water bodies and estimates of streamflow and velocity are used in SPARROW to identify reservoir retention and in-stream loss factors. NHDPlusV2 climatic and land surface attributes can be used in SPARROW to identify potential factors in the delivery of nutrients from the land surface to streams. NHDPlusV2 data is also being used in select areas for a USGS Web-based application, called StreamStats. StreamStats provides tools to interactively select any point in the implemented areas, delineate watersheds, and to obtain streamflow and watershed characteristics for the selected point. NHDPlusV2 has been designed to accommodate many users' needs for future applications. NHDPlusV2 provides the framework and tools necessary to customize the behavior of the network relationships as well as building upon the attribute database, for which the user can assign their own data to the network.

A crosswalk table between NHDPlus version 2.1 flowlines (using the unique field COMID) and the Watershed Boundary Dataset (WBD) 12-digit-hydrologic units (HU-12) is provided for the 48 contiguous United States. The crosswalk table provides a WBD HU-12 assignment for every networked flowline in the NHDPlus. In this way, the network developed for navigation and modeling, NHDPlus, is aligned with accounting units of the WBD HU-12s to the extent possible given the assumptions that were made in creating each. A crosswalk table for NHDPlus isolated sinks was produced by a simple overlay process where the sinks were assigned HU-12 values based on their position relative to the WBD snapshot HU-12s. This table was integrated with the flowline associations into one crosswalk table for both feature types. There is good alignment between aggregated NHDPlus catchments and WBD HU-12 units in many locations. These are areas where the flows and chemical or nutrient loads that are accumulated leave the HU-12 at a single outlet and are passed down to the next HU-12 downstream (or to the coast) as is assumed in the WBD model. A second pass through the data was made to account for any secondary outlet from each HU-12. The location of a secondary outlet with a significant drainage from that HU was identified in the alignment with NHDPlus. This resulted in a reduction in areas of mismatch as well as an improved crosswalk table. The crosswalk table should be used with caution in areas where efforts could be made to improve the data. For example, with medium-resolution NHD, a better definition of flow direction of the flowlines in Southern Florida would result in more flowlines being included in the “networked” flowlines with catchments, and that, in turn, would result in better alignment between NHDPlus catchments and HU-12s. Correcting errors in either the medium-resolution NHD or WBD would improve the alignment between the two datasets.

Links to a geodatabase (gdb 10.1) download for the National Hydrography Dataset (NHD) for the state of Colorado. The NHD contains data on streams, areas, points, flowlines, and watershed basin boundaries in Hydrologic Units 2, 4, 6, 8, 10, and 12. Data is maintained by the U.S. Geological Survey.

This resource contains medium-resolution (1:100k) National Hydrography Dataset (NHDPlus) [1] map data for a region of 23 Hydrologic Unit Code (HUC) 6-digit (HUC6) basins around the Hurricane Irma impact zone across Florida, Georgia, and the Carolinas. This includes 5,236 subwatersheds, 217,308 catchments, and 220,418 flowlines.

State and county boundaries were obtained from the Esri Living Atlas [2].

USGS active stream gages can be downloaded from the USGS National Water Information System (NWIS) [3], or visualized at the USGS WaterWatch site [4]. NOAA Advanced Hydrologic Prediction System (AHPS) river forecast points can be downloaded as well [5]. Many of these are co-located with USGS NWIS gages to leverage authoritative observation data.

References [1] NHDPlus Version 2 [http://www.horizon-systems.com/NHDPlus/V2NationalData.php] [2] Esri Living Atlas [https://livingatlas.arcgis.com] [3] USGS NWIS [https://waterdata.usgs.gov/nwis] [4] USGS WaterWatch [https://waterwatch.usgs.gov] [5] NOAA AHPS [https://water.weather.gov/ahps/forecasts.php]

This tabular data set contains information on bankfull depth, width and cross-sectional area for each NHDPlus version 2.1 data suite (NHDPlusv2) flowline (Moore and Dewald, 2016) for the conterminous United States. These data were created using regional regression equations outlined in Bieger and others (2015). The equations predict bankfull width, depth and cross-sectional area as a function of drainage area for eight Physiographic Divisions of the conterminous United States (Fenneman, 1946).

Perennial streams in Idaho have been modeled using regression equations for 7-day, 2-year low flows (7Q2) described in Wood and others (2009, U.S. Geological Survey Scientific Investigations Report 2009-5015). The model produces "synthetic" streams based on 10-meter resolution digitial elevation models that have been processed to agree closely with 1:24,000-scale National Hydrography Dataset flowlines. See Larger_Work_Citation report text for a complete description of the modeling process. In this dataset, the synthetic stream lines have been indexed to the NHDPlus Version 01_02 (schema version 1, data version 2). Points along the synthetic streams where 7Q2 model estimates exceeded 0.1 cubic feet per second were snapped to the NHDPlus 1:100,000-scale flowlines, and then traced downstream using the NHDPlus network. The data are presented in the form of a dBase-format event table. The traced line events correspond to synthetic stream lines having PerCode values of 2 or 3.