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February 7, 2022

Users can now easily give their water data the equivalent of a street address on the stream network thanks to the new web-based USGS Hydrography Addressing Tool, or HydroAdd. As of January 28, 2022, HydroAdd is available to all users

Hydrographic addressing, also referred to as linear referencing, indexing, or linking, is a means to align water data with the mapped stream network. Tools for addressing water data provide reference locations on the stream network, similar to street addresses, that can be attached to a user’s data records. Any kind of water-related information can be addressed, such as hydrology, geomorphology, water quality, biology, regulations, and more. 

Introducing HydroAdd 

HydroAdd is a web-based tool that enables users to address data to the National Hydrography Dataset (NHD). HydroAdd allows users to keep their data synchronized with the NHD as the stream network is updated, so users can continually track and manage geospatial assets. Because HydroAdd is a web-based tool, multiple users can collaborate on shared projects.

Benefits of Hydrographic Addressing 

The benefits of addressed water data are numerous. Once water data has been addressed to the NHD, it can be analyzed within the stream network to understand relationships between different data records or observations. For example, addressing water data allows scientists to accurately portray the distance between water quality samples and an environmental spill, the downstream relationship of a fish population to a dam, or time of travel analyses of pollutants. 

HydroAdd interface screen capture
HydroAdd interface screen capture. This image is used in the news article HydroAdd Available to All Users Jan 28!

How to Access HydroAdd 

To use HydroAdd, a user must have an active ArcGIS Online (AGOL) account. HydroAdd displays a user’s data as an editable web features service from AGOL. More information on using HydroAdd is available at  

HydroAdd into the Future 

HydroAdd is just one part of the broader USGS effort to remake how water data is shared and discovered. Building on the decades of experience developing and managing the National Hydrography Dataset, the USGS is establishing the 3D Hydrography Program (3DHP) initiative to completely refresh the Nation’s hydrography data and improve discovery and sharing of water data.  When fully implemented, 3DHP is estimated to provide more than $1 billion in benefits every year, in addition to myriad societal benefits. Additionally, decisions that directly affect water will be better informed. 

3DHP will establish an information infrastructure, or “infostructure”, to support sharing and discovering water-related information in the context of the 3DHP stream network. The 3DHP stream network will be a significant improvement to the level of detail, currency, and inclusion of hydrography data by deriving a 3D stream network from high-quality 3D Elevation Program (3DEP) data. The 3DHP infostructure will also provide the geospatial underpinning for the Internet of Water (IoW), which seeks to advance the transformation and modernization of water data infostructure in the U.S. The 3DHP infostructure will be collaborative, open, and available to everyone. 

HydroAdd will be a key component of the 3DHP infostructure. The 3DHP infostructure will also include tools to search and discover linked water data within the context of the stream network. 

Video Transcript
For an overview presentation of HydroAdd, please visit: Hydrologic Addressing Tool: Initial Release - YouTube. 

For a demonstration, training, or questions about HydroAdd, contact

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