WestDAAT NLDI Geoconnex Documentation

Note: this page is being reviewed and updated over time. 

This page contains controls that allow a user to utilize the Hydro Network-Linked Index (NLDI) and Geoconnex Framework tool.  This tool is a system that can index spatial and river network-linked data and navigate the river network to allow the discovery of indexed information. NLDI puts a restful application programming interface (API) in front of the National Hydrography dataset.  For further information, see here: https://waterdata.usgs.gov/blog/nldi-intro/


  • The NLDI tool implemented in WestDAAT queries indexes water rights sites up to 500 kilometers (~310 miles) upstream or downstream of the selected location. While longer distances can be supported, the volume of data can be challenging to process for very larger river basins which may impact the user experience.
  • NLDI returns all the USGS and EPA-indexed sites to the search area which can be overwhelming. Further metadata filters are needed to limit the search to sites that have certain parameters of interest such as streamflow and total dissolved solids. WestDAAT provides links to external landing pages provided by USGS or EPA. Those external pages are outside the control of WaDE and users should refer to their providers’ metadata. 


Geoconnex is a system for connecting water data from different data providers via geographic location. Geoconnex rests on the widespread adoption of metadata best practices, automatically harvesting metadata and indexing data to real-world hydrologic features (e.g. lakes, reservoirs, wells, streams, water distribution systems, monitoring locations). The resulting water-specific search index will be browsable from a common water metadata catalog in both a human and machine-readable format. WestDAAT’s data is compliant with Geoconnex by (1) providing persistent identifiers and landing pages for all water rights data, and (2) including universal metadata where web crawlers can harvests links between data in WestDAAT and hydrologic features. More information is available here https://internetofwater.org/geoconnex/

This tool has the following applications for WaDE: (1) drag and drop pin tool, (2) text entry box for latitude values, (3) text entry box for longitude values, (4) toggle button to indicate the direction of the query of site data, (5) toggle button to receive site information for other federal agencies as part of the Geoconnex Framework.

1. Drag and Drop Pin Tool
A drag-and-drop pin that allows a user to generate NLDI results wherever they want on the accompanying map. After doing so, the latitude and longitude text box entries are auto-filled.  Uses EPSG: 4326 geographic coordinate system.

2. Latitude
The optional text entry field for latitude values for the NLDI query.  Auto-filled with the above Drag and Drop Pin tool. Uses EPSG: 4326 geographic coordinate system.

3. Longitude
The optional text entry field for longitude values for the NLDI query.  Auto-filled with the above Drag and Drop Pin tool. Uses EPSG: 4326 geographic coordinate system.

4. Direction
Toggle button(s) that indicate the direction of the river index query.  Can be toggled on or off.

5. Scope of Query
Toggle button(s) to indicate the scope of site data to query and return. Can be toggled on or off. Includes options from other Geoconnex Framework partners. Options at this time include (1) WaDE water right sites, (2) USGS stream gage sites, and (3) EPA water quality sites.