Skip to main content
U.S. flag

An official website of the United States government

The following tools are provided to assist in the use of USGS Hydrography Datasets. Any problems encountered when using these tools should be reported to National Hydrography Support.

Tools for National Hydrography Datasets

Page NavigationHydrographic Addressing (HydroAdd and HEM) | NHD Utilities | Geographic Names Information System (GNIS

Hydrographic Addressing

►Contact: To learn more about HydroAdd, contact | To learn more about HEM contact

Hydrographic addressing, also referred to as linear referencing, indexing, or linking, is a means to align data features relevant to the stream network to be coincident with National Hydrography Dataset (NHD) features. Addressing data to the NHD enables it to be used as a base for analysis and knowledge. Any kind of hydro-related observations can be addressed to the NHD such as observations relating to hydrology, geomorphology, water quality, biology, regulations, etc.


Hydrography Addressing (HydroAdd) Tool

The Hydrography Addressing Tool, or HydroAdd, is a web-based tool that allows users to address data to the National Hydrography Dataset (NHD). The addressing process also spatially joins some NHD flowline attributes to data features being addressed. Because HydroAdd is a web-based tool, multiple users can collaborate on shared projects.

To use HydroAdd you must have an active Esri ArcGIS Online account.


Hydrography Event Management (HEM) Tool

The Hydrography Event Management (HEM) Tool is a desktop addressing tool for use in Esri ArcMap. The HEM tool can create point, line, and polygon events. 

To use HEM tools, you must have ArcMap 10.7.1.

Download: HEM Tool for ArcGIS 10.7.1

NHD Utilities

►Contact: For more information, email National Hydrography Support.

Note: These tools are unsupported. If users need previous versions of the NHD Utilities contact National Hydrography Support.

The NHD Utilities is a suite of stand-alone software functions that were designed to help users manipulate National Hydrography Dataset (NHD) data. These tools are not necessarily part of the maintenance/update process for NHD, but are very useful to those performing different sorts of data manipulation and analysis with NHD data. This suite of tools includes; Network Builder, Build Flow, M-Value Utility, Geodatabase to Shapefile (GDB2Shp), Shapefile to Geodatabase (Shp2GDB), Subset by Polygon, and NHD Merge. The USGS NGTOC maintains on one version of these NHD Utilities usually for the current version of the ESRI ArcGIS application.

Download: NHD Utilities for ArcGIS 10.7.1

What's included:

  • NHD Network Builder: The NHD uses a utility geometric network within the ESRI geodatabase. This network allows the user to use ESRI’s Utility Network Analyst extension to perform certain analysis techniques. This network must be deleted when performing edits or re-projecting the NHDFlowline feature class. After re-projecting or altering NHDFlowline data, it is necessary to re-build the geometric network to restore flow and directionality to work with Utility Network Analyst. Network Builder is a tool that rebuilds the geometric network, creates and sets the “Enabled” field, and sets the flow direction within the context of the “FlowDir” attribute. The tool does not rebuild or update the NHD Flow table.

  • NHD Build Flow: The NHD Build Flow utility requires the input of an NHD subbasin file geodatabase. The tool builds a geometric network using the NHDFlowline feature class within the geodatabase. Each node within the geometric network represents a confluence of two or more NHDFlowline features. This utility uses these nodes to populate the NHDFlow table with in and out flow directions for each node, based on the FlowDir attribute within the NHDFlowline feature class. The result is a populated NHDFlow table that shows the flow of water throughout the network.

  • M-Value Utilities: M-Values, or measures, are the percentage upstream from a given location based on the features reachcode on an NHDFlowline. Measures range from 0-100 percent with 0 being the most downstream point of a reach (mouth), and 100 being the most upstream end of the reach (source). This is opposite of the flow/digitized direction of the feature. The M-Value Utility assigns measures to reached flow lines only. Each reached feature will have measure associated with the reach code assigned to that feature. The M-Value provides the networked location of a point event or the extent of a linear event along a reach.

  • GDB2Shp: This utility will convert a NHD ESRI file geodatabase into a set of shapefiles and DBF tables which can then be used by other software. The output is stored under a specific folder directory specified by the user’s system environment variables. Please read the NHD Utilities User Guide in order to obtain more information.

  • Shp2GDB: This utility will convert a series of ESRI Shapefile and DBF tables that are stored in an NHD format to an ESRI file geodatabase. The input must be correctly formatted and located in the user’s system environment variables folder on order to be converted. Please read the NHD Utilities User Guide in order to obtain more information.

  • Subset by Polygon: The Subset by Polygon tool (ESRI Add-in) works within an ArcGIS session and is not a standalone executable. The tool allows users to create subsets of the NHD data based on one or more polygons from a CustomArea feature class within a NHD geodatabase. This tool only works on fully populated NHD data.

  • NHD Merge: The NHD Merge tool joins two or more NHD geodatabases into a single geodatabase.  For ease of use, it is recommended that the input geodatabases be in the same folder.

Geographic Names Information System (GNIS)

Access the Geographic Names Information System (GNIS) to check, submit new, or make changes to names in GNIS.