NHD Project Status
Network Improvement
Hydro/Image Integration
The goal of Hydro/Image Integration is to ensure hydrography data is sufficient to support accuracy requirements for USTopo production. This is done by:
Reviewing current NAIP imagery and updating the NHD to add lake/ponds 500,000 meters or larger and modifying the position of lake/ponds that are: greater than 1.0 sq km, that do not have an elevation value, if the shorelines are off by more than 500 ft, and to realign stream/rivers polygon features that are greater than 100 ft wide, when the position of the banks have moved more than 1000 ft.
National Water Information System Point-Event Indexing
The goal of National Water Information System (NWIS) Indexing Project is to create high-resolution NHD stream gage and water quality event features from NWIS data by indexing (snapping) the station to the appropriate position on the NHDFlowline. Links to external scientific data are known in the NHD as events. Because the NHD is designed as a connected flow network, events make many kinds of scientific analysis possible; such as how a source of poor water quality upstream might affect a fish population downstream, or how dams affect water temperatures downstream. The USGS is currently adding point events to the NHD including steam gages, water quality stations, dams, and diversions. The map shows progress of NWIS gage and water quality station indexing by Subregion.
