This data release includes datasets with annual streamflow statistics determined with the Indicators of Hydrologic Alteration software and R source code to create time-series plots with overlaid locally weighted scatterplot smoothing (lowess) lines.

This data release includes datasets with annual streamflow statistics determined with the Indicators of Hydrologic Alteration software and R source code to create time-series plots with overlaid locally weighted scatterplot smoothing (lowess) lines.

In 2016, non-interpretive streamflow statistics were compiled for streamgages located throughout the Nation and stored in the StreamStatsDB database for use with StreamStats and other applications. Two previously published USGS computer programs that were designed to help calculate streamflow statistics were updated to better support StreamStats as part of this effort. These programs are named “GNWISQ” (Get National Water Information System Streamflow (Q) files) and “QSTATS” (Streamflow (Q) Statistics). Statistics for 20,438 streamgages that had 1 or more complete years of record during water years 1901 through 2015 were calculated from daily mean streamflow data; 19,415 of these streamgages were within the conterminous United States. About 89 percent of the 20,438 streamgages had 3 or more years of record, and 65 percent had 10 or more years of record. Drainage areas of the 20,438 streamgages ranged from 0.01 to 1,144,500 square miles. The magnitude of annual average streamflow yields (streamflow per square mile) for these streamgages varied by almost six orders of magnitude, from 0.000029 to 34 cubic feet per second per square mile. About 64 percent of these streamgages did not have any zero-flow days during their available period of record. The 18,122 streamgages with 3 or more years of record were included in the StreamStatsDB compilation so they would be available via the StreamStats interface for user-selected streamgages.

In 2016, non-interpretive streamflow statistics were compiled for streamgages located throughout the Nation and stored in the StreamStatsDB database for use with StreamStats and other applications. Two previously published USGS computer programs that were designed to help calculate streamflow statistics were updated to better support StreamStats as part of this effort. These programs are named “GNWISQ” (Get National Water Information System Streamflow (Q) files) and “QSTATS” (Streamflow (Q) Statistics). Statistics for 20,438 streamgages that had 1 or more complete years of record during water years 1901 through 2015 were calculated from daily mean streamflow data; 19,415 of these streamgages were within the conterminous United States. About 89 percent of the 20,438 streamgages had 3 or more years of record, and 65 percent had 10 or more years of record. Drainage areas of the 20,438 streamgages ranged from 0.01 to 1,144,500 square miles. The magnitude of annual average streamflow yields (streamflow per square mile) for these streamgages varied by almost six orders of magnitude, from 0.000029 to 34 cubic feet per second per square mile. About 64 percent of these streamgages did not have any zero-flow days during their available period of record. The 18,122 streamgages with 3 or more years of record were included in the StreamStatsDB compilation so they would be available via the StreamStats interface for user-selected streamgages.

The U.S. Geological Survey (USGS), in cooperation with the Wyoming Water Development Office, developed streamflow statistics for active (through September 30, 2021) and discontinued USGS streamgages in and near Wyoming with 10 or more years of daily mean streamflow record. The computation of streamflow statistics for USGS streamgages is part of a larger study to develop a StreamStats application (www.usgs.gov/streamstats) for the State of Wyoming (https://www.usgs.gov/centers/wyoming-montana-water-science-center/science/wyoming-streamstats). StreamStats is a web-based computer program that can be used to delineate drainage areas, determine basin characteristics, and compute streamflow statistics at locations with and without streamgages (https://streamstats.usgs.gov/ss/; Ries and others, 2024). Streamflow at each streamgage was assessed for degree of human alteration owing to dams and diversions before streamflow statistics were computed. Streamflow records from 631 streamgage periods of record were used to compute basic, seasonal, and flow-duration statistics; records for 390 streamgage periods of record were used to compute n-day statistics and statistics that can be used for regional regression. Methods used to compute the summary statistics contained in this data release are described in an accompanying report (Armstrong and others, 2025).

The U.S. Geological Survey (USGS), in cooperation with the Wyoming Water Development Office, developed streamflow statistics for active (through September 30, 2021) and discontinued USGS streamgages in and near Wyoming with 10 or more years of daily mean streamflow record. The computation of streamflow statistics for USGS streamgages is part of a larger study to develop a StreamStats application (www.usgs.gov/streamstats) for the State of Wyoming (https://www.usgs.gov/centers/wyoming-montana-water-science-center/science/wyoming-streamstats). StreamStats is a web-based computer program that can be used to delineate drainage areas, determine basin characteristics, and compute streamflow statistics at locations with and without streamgages (https://streamstats.usgs.gov/ss/; Ries and others, 2024). Streamflow at each streamgage was assessed for degree of human alteration owing to dams and diversions before streamflow statistics were computed. Streamflow records from 631 streamgage periods of record were used to compute basic, seasonal, and flow-duration statistics; records for 390 streamgage periods of record were used to compute n-day statistics and statistics that can be used for regional regression. Methods used to compute the summary statistics contained in this data release are described in an accompanying report (Armstrong and others, 2025).

This child item includes daily mean streamflow data obtained from the U.S. Geological Survey (USGS) National Water Information System database (https://doi.org/10.5066/F7P55KJN) and subsequently used in the computation of streamflow statistics. Daily mean streamflow data for some streamgages were removed from the analyses if the daily streamflows were determined to be incorrect, estimated, or had other problems. Streamflow at each streamgage was assessed for degree of human alteration owing to dams and diversions before streamflow statistics were computed. Methods used to remove daily mean streamflows, assess alteration, and compute the summary statistics contained in this data release are described in an accompanying report (Armstrong and others, 2025). Daily mean streamflow data for the period of record at each USGS streamgage used in the analyses are grouped into 15 folders organized by the 4-digit hydrologic unit code (HUC; https://water.usgs.gov/GIS/huc.html) in which the streamgage is located. The content of these folders is described in this metadata file. A table describing characteristics of the streamgages used in the analyses is provided in text file "AtSite_Table1_StreamgageSummary.txt."

The U.S. Geological Survey (USGS), in cooperation with the Wyoming Water Development Office, developed streamflow statistics for active (through September 30, 2021) and discontinued USGS streamgages in and near Wyoming with 10 or more years of daily mean streamflow record. The computation of streamflow statistics for USGS streamgages is part of a larger study to develop a StreamStats application (www.usgs.gov/streamstats) for the State of Wyoming (https://www.usgs.gov/centers/wyoming-montana-water-science-center/science/wyoming-streamstats). StreamStats is a web-based computer program that can be used to delineate drainage areas, determine basin characteristics, and compute streamflow statistics at locations with and without streamgages (https://streamstats.usgs.gov/ss/; Ries and others, 2024). Streamflow at each streamgage was assessed for degree of human alteration owing to dams and diversions before streamflow statistics were computed. Streamflow records from 631 streamgage periods of record were used to compute basic, seasonal, and flow-duration statistics; records for 390 streamgage periods of record were used to compute n-day statistics and statistics that can be used for regional regression. Methods used to compute the summary statistics contained in this data release are described in an accompanying report (Armstrong and others, 2025).

This child item includes daily mean streamflow data obtained from the U.S. Geological Survey (USGS) National Water Information System database (https://doi.org/10.5066/F7P55KJN) and subsequently used in the computation of streamflow statistics. Daily mean streamflow data for some streamgages were removed from the analyses if the daily streamflows were determined to be incorrect, estimated, or had other problems. Streamflow at each streamgage was assessed for degree of human alteration owing to dams and diversions before streamflow statistics were computed. Methods used to remove daily mean streamflows, assess alteration, and compute the summary statistics contained in this data release are described in an accompanying report (Armstrong and others, 2025). Daily mean streamflow data for the period of record at each USGS streamgage used in the analyses are grouped into 15 folders organized by the 4-digit hydrologic unit code (HUC; https://water.usgs.gov/GIS/huc.html) in which the streamgage is located. The content of these folders is described in this metadata file. A table describing characteristics of the streamgages used in the analyses is provided in text file "AtSite_Table1_StreamgageSummary.txt."

This data release contains values of 29 streamflow statistics computed from modeled and observed daily streamflows from October 1, 1983, through September 30, 2016 at 1,257 streamgages in the 19 study regions defined by Falcone (2011) covering the conterminous United States. The streamflow statistics were computed at GAGES-II non-reference streamgages (Falcone, 2011), determined to be affected by only irrigation or regulation among antrhopogenic influences. At each streamgage, statistics were computed from daily streamflow observations, from daily streamflow time series computed using the National Hydrologic Model-Precipitation Runoff Modeling System (NHM-PRMS) model (the “by headwater” and "by observation" calibrations with Muskingum routing; Hay and LaFontaine, 2020), and from daily streamflow time series computed using five statistical time series models fitted to reference basins (Russell and others, 2021). The data release comprises nine .csv files. The streamflow statistics values are provided in eight of these files, one each for the observed, the two NHM-PRMS calibrations, and the five statistical time series models. The remaining file is a summary table, which provides period-of-record information for each streamgage. References cited: Falcone, J.A., 2011, GAGES-II: Geospatial Attributes of Gages for Evaluating Streamflow [digital spatial dataset]: U.S. Geological Survey Water Resources NSDI Node web page, https://water.usgs.gov/lookup/getspatial?gagesII_Sept2011. Hay, L.E., and LaFontaine, J.H., 2020, Application of the National Hydrologic Model Infrastructure with the Precipitation-Runoff Modeling System (NHM-PRMS), 1980-2016, Daymet Version 3 calibration: U.S. Geological Survey data release, https://doi.org/10.5066/P9PGZE0S. Russell, A.M., Over, T.M., Farmer, W.H., and Miles, K.J., 2021, Statistical daily streamflow estimates at GAGES-II non-reference streamgages in the conterminous Unites States, Water Years 1981-2017: U.S. Geological Survey data release, https://doi.org/10.5066/P9PA9PKM.