Tools for National Hydrography Datasets
Page Navigation: Hydrographic Addressing (HydroAdd and HEM) | NHD Utilities | Geographic Names Information System (GNIS)
Hydrographic Addressing
►Contact: To learn more about HydroAdd, contact hydroadd@usgs.gov | To learn more about HEM contact hem@usgs.gov
Notice: The legacy HydroAdd tool will be retired December 31, 2025. Critical components of the legacy HydroAdd system pose potential information technology risks. An updated version of HydroAdd compatible with 3DHP is in development.
Data you have addressed and published will remain available through AGOL, but you’ll want to complete any open projects by the end of the month.
We apologize for the inconvenience. If you have any questions or concerns please contact 3dhp@usgs.gov.
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.
Geographic Names Information System (GNIS)
Access the Geographic Names Information System (GNIS) to check, submit new, or make changes to names in GNIS.
