Here’s the release from the USGS:
As part of an ongoing effort to improve the suite of hydrography web-based map services, the USGS will separate the services for the National Hydrography Dataset (NHD) and Watershed Boundary Dataset (WBD).
Currently, the NHD dynamic service, “Hydrography (inc. watersheds)” includes both NHD and WBD layers. The existing address will be updated to include only NHD layers, and a new endpoint will be designated for WBD services.
The NHD and WBD represent inland waters for the U.S. as a part of The National Map. The NHD represents the drainage network with features such as rivers, streams, canals, lakes, ponds, coastline, dams, and streamgages. The WBD represents drainage basins as enclosed areas in eight different size categories.
Focusing these services to two endpoints enables the USGS to isolate changes and issues, and continue to improve the performance of each set of services independently. When complete, users will have the choice to consume the services of NHD or WBD independently. Accessing the WBD services will not require users to consume the additional NHD layers, and accessing NHD services will not require users to have to consume the additional WBD layers. Separating the services and increasing resources available has improved performance.
This change will impact applications presently consuming the combined NHD and WBD layers from the existing service address. Once this is implemented, users who would like to consume the WBD dynamic services will need to use the new service endpoint. In addition, users currently consuming the combined service may need to update application configurations for display of the desired layers.
Additionally, two NHD/WBD-related web services are being retired at the end of April. See the summary below for more information.
An announcement will be posted in the “What’s New” section on the The National Map website once changes are implemented.
New – Hydrography data service endpoints:
1. National Hydrography Dataset
Function: Provides national hydrography data Endpoint: https://services.nationalmap.gov/arcgis/rest/services/nhd/MapServer This NHD endpoint remains the same, the WBD layers have been removed.
2. National Watershed Boundary Dataset
Function: Provides watershed boundary data Endpoint: https://services.nationalmap.gov/arcgis/rest/services/wbd/MapServer
3. Hydrography (cached)
Function: Provides a fast USGS Topo styled hydrography overlay Endpoint: https://basemap.nationalmap.gov/arcgis/rest/services/USGSHydroCached/MapServer This service was announced and made public March 2017 and is also available as a WMTS service.
Retiring at the end of April 2017
NHD Base Map (former primary tile cache) Function: Cached base map of hillshade, NHD and WBD combined Endpoint: https://basemap.nationalmap.gov/arcgis/rest/services/USGSHydroNHD/MapServer
USGS NHD Base Map – Below 18K Scale Dynamic
Function: Dynamic map service used below 18K to work along with older NHD Base Map cache. This also contains hillshade, NHD and WBD combined Endpoint: https://services.nationalmap.gov/arcgis/rest/services/USGSHydroNHDLarge/MapServer
For any questions, comments, or concerns regarding this update, please contact Ariel Doumbouya (firstname.lastname@example.org).