StreamStats was initially developed through a cooperative effort of the USGS and ESRI, Inc.* It is an integrated GIS application that is partly based on a combination of ArcGIS Server technology and the ArcHydro Tools, as well as on Python scripts. Most StreamStats functionality is available as web services. StreamStats incorporates a map-based user interface for site selection; a database that contains information for data-collection stations; a GIS program that delineates drainage-basin boundaries and measures physical and climatic characteristics of the drainage basins; and a GIS database that contains data needed for delineating basins, for measuring drainage-basin characteristics, and for locating sites of interest in the user interface. GIS data needed for delineations generally were developed by integrating elevation data from the USGS 3D Elevation Program, streams from the National Hydrography Dataset, and previously determined watershed boundaries from the Watershed Boundary Dataset. After StreamStats measures the drainage-basin characteristics for a selected site, the values are input to a separate program named the USGS National Streamflow Statistics (NSS) program, which is a Microsoft Windows program that contains all of the USGS-developed equations for estimating flood-frequency statistics in the Nation. NSS has been modified for StreamStats so that it can also contain equations for estimating other types of streamflow statistics. All of the equations in NSS are documented through links to each individual State from the NSS Web site. Output from NSS and from the Access database is presented to StreamStats users pop-up windows on their computer desktop. 

*The use of trade or product names is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey.