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).

Identifying long-term trends in water availability, including surface water quantity, is a key part of the U.S. Geological Survey (USGS) Integrated Water Availability Assessments (IWAAs) mission. This data release includes input and output data used in Mann-Kendall trend analyses to characterize streamflow conditions at 124 USGS streamgages in the Upper Colorado River Basin for water years 1982 through 2021. The Upper Colorado Riven Basin is defined here as the basin area upstream of USGS streamgage Colorado River above Lee's Ferry, AZ (USGS site number 09380000). Input data included annual (111 streamgages), seasonal (119 streamgages), and monthly (121 streamgages) streamflow metrics, calculated from daily mean streamflow data from the USGS National Water Information System (NWIS) database. Annual streamflow metrics include mean and median annual streamflow, 1-day, 7-day, and 30-day maximum annual streamflow; 1-day, 7-day, and 30-day minimum annual streamflow; and the date of the center of volume (the date on which 50 percent of the annual streamflow has passed by a streamgage). Seasonal metrics were calculated for Fall (October-December), Winter (January-March), Spring (April-June), and Summer (July-September) and include mean and median seasonal streamflow, 1-day and 7-day maximum seasonal streamflow, and 1-day and 7-day minimum seasonal streamflow. Monthly metrics include mean and median monthly streamflow, 1-day and 7-day maximum monthly streamflow, and 1-day and 7-day minimum monthly streamflow. Trend analyses using the Mann-Kendall test were completed on the annual, seasonal, and monthly metrics, which were passed through a series of data completeness filters to ensure robust trend analyses. Trend analyses were conducted for climate years 1982 through 2021 for low-flow metrics (where each climate year represents April – March), and trend analyses were conducted for water years 1982 through 2021 for all other metrics (where each water year represents October – September).

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.

This child item contains peak-flow input data files for PeakFQ for peak-flow frequency analyses for selected streamgages based on data through water year 2022. The file format is called WATSTORE (National Water Data Storage and Retrieval System) available from NWISWeb (http://nwis.waterdata.usgs.gov/usa/nwis/peak).

This dataset was produced by the U.S. Geological Survey (USGS) in cooperation with the Wyoming Water Development Office for the purpose of delineating drainage basins and performing hydrologic analysis in the Wyoming StreamStats application. The data are raster representations of the fundamental dataset layers necessary for the functionality of StreamStats application within the Wyoming StreamStats study area. The StreamStats application provides access to spatial analytical tools that are useful for water-resources planning and management, and for engineering and design purposes. The map-based user interface can be used to delineate drainage areas, calculate basin characteristics, and estimates of flow statistics, and more. The study boundary for data in this data release is defined by the extent of all HUC08 watersheds flowing in or out of the state of Wyoming.

Peak-flow frequency analysis is crucial in various water-resources management applications, including floodplain management and critical structure design. Federal guidelines for peak-flow frequency analyses, provided in Bulletin 17C, assume that the statistical properties of the hydrologic processes driving variability in peak flows do not change over time and so the frequency distribution of annual peak flows is stationary. Better understanding of long-term climatic persistence and further consideration of potential climate and land-use changes have caused the assumption of stationarity to be reexamined. This data release contains input data and results of a study investigating hydroclimatic trends in peak streamflow (peak flow) in the Central United States, including nine states (Iowa, Illinois, Michigan, Minnesota, Missouri, Montana, North Dakota, South Dakota, and Wisconsin). Peak flow records from unregulated U.S. Geological Survey (USGS) streamgages were used to evaluate changes over 30-, 50-, 75-, and 100-year trend periods, all ending in water year 2020. This data release contains station lists of the streamgages used in each of the nine states, the peak streamflow input data and peak streamflow analysis results, and the climate input data and climate analysis results. See "Station_Lists.zip" on the landing page for station lists (in text file format) for each state included in the study.

We projected future streamflow outcomes arising from climate change for the southwestern United States during the 21st century due to climate change under two possible greenhouse gas concentration pathways (RCP4.5 and 8.5). The results inform water managers about the future risks of drought in their water resource regions by providing bounds on the possible locations and extents of streamflow loss. To get to these results, we used downscaled future and historical climate data from seven models to drive a new, calibrated SPAtially Referenced Regression On Watershed attributes (SPARROW) streamflow model (Wise and others, 2019, Miller and others, 2020). Temperature and precipitation data come from the NASA Earth Exchange (NEX) Downscaled Climate Projections (NEX-DCP30, Thrasher and others, 2013 and Thrasher and others, 2015), and actual and potential evapotranspiration come from the NEX-DCP30 temperature and precipitation used in the Monthly Water Balance Model (MWBM, Hostetler and Alder, 2016 and Alder, 2017a,b,c). This data set comprises climate data preprocessing code to convert the gridded, monthly-scale climate data to reach scale multidecadal averages for the intervals 1975-2005, 2020-2049, 2040-2069 and 2070-2099, the model input (data1) and model control files, the model code, model results files, and code to post-process and analyze the streamflow model results. The raw climate data (NEX-DCP30, MWBM), and SPARROW model calibration documentation are publicly available elsewhere and are cross linked with this data release (see crossref section). The full data preparation, modeling, and analysis methods, as well as results are described in Miller and others, (2021)

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.