USGS Streamgages Linked to the Medium Resolution NHD

The locations of approximately 23,000 current and historical U.S. Geological Survey (USGS) streamgages 
in the United States and Puerto Rico (with the exception of Alaska) have been snapped to the medium resolution 
National Hydrography Dataset (NHD).  The NHD contains geospatial information about mapped surface-water 
features, such as streams, lakes, and reservoirs, etc., creating a hydrologic network that can be used to 
determine what is upstream or downstream from a point of interest on the NHD network. An automated 
snapping process made the initial determination of the NHD location of each streamgage. These initial NHD 
locations were comprehensively reviewed by local USGS personnel to ensure that streamgages were snapped 
to the correct NHD reaches. About 75 percent of the streamgages snapped to the appropriate NHD reach 
location initially and 25 percent required adjustment and relocation.  This process resulted in approximately 
23,000 gages being successfully snapped to the NHD.
		 
This dataset contains the latitude and longitude coordinates of the point on the NHD to which the streamgage 
is snapped and the location of the gage house for each streamgage. A process known as indexing may be used 
to create reference points (event tables) to the NHD reaches, expressed as a reach code and measure (distance 
along the reach). Indexing is dependent on the version of NHD to which the indexing is referenced. These data are 
well suited for use in indexing because nearly all the streamgage NHD locations have been reviewed and adjusted 
if necessary, to ensure they will index to the appropriate NHD reach.
		
Flow characteristics were computed from the daily streamflow data recorded at each streamgage for the period of 
record. The flow characteristics associated with each streamgage include:
		
First date (year, month, day) of streamflow data
Last date (year, month, day) of streamflow data
Number of days of streamflow data
Number of days of non-zero streamflow data
Minimum and maximum daily flow for the period of record (cubic feet per second)
Percentiles (1, 5, 10, 20, 25, 50, 75, 80, 90, 95, 99) of daily flow for the period of record (cubic feet per second)
Average and standard deviation of daily flow for the period of record (cubic feet per second)
Mean annual base-flow index (BFI) computed for the period of record (fraction, ranging from 0 to 1)
Year-to-year standard deviation of the annual base-flow index computed for the period of record (fraction)
Number of years of data used to compute the base-flow index (years)
		
The streamflow data used to compute flow characteristics were copied from the NWIS-Web historical daily discharge 
archive (http://waterdata.usgs.gov/nwis/sw) on June 15, 2005.

Tags: alabama, arizona, arkansas, base-flow-index, california, colorado, connecticut, deleware, district-of-columbia, florida, gages, gaging-stations, georgia, hawaii, hydrography, idaho, illinois, indiana, inlandwaters, iowa, kansas, kentucky, louisiana, maine, maryland, massachusetts, michigan, minnesota, mississippi, missouri, montana, national-hydrography-dataset, nebraska, nevada, new-hampshire, new-jersey, new-mexico, new-york, nhd, north-carolina, north-dakota, ohio, oklahoma, oregon, pennsylvania, puerto-rico, rhode-island, south-carolina, south-dakota, streamflow-data, streamflow-statistics, streamgages, tennessee, texas, united-states, united-states-of-america, usa, usgs-d4d13c9d-dc52-4fc9-b8f6-cc42ce9b1a10, usgs-streamgage-network-locations-for-nhd-version-june-2002-medium-resolution, utah, vermont, virginia, washington, west-virginia, wisconsin, wyoming
Organization: Department of the Interior