Perennial streams in Idaho have been modeled using regression equations for 7-day, 2-year low flows (7Q2) described in Wood and others (2009, U.S. Geological Survey Scientific Investigations Report 2009-5015). The model produces "synthetic" streams based on 10-meter resolution digitial elevation models that have been processed to agree closely with 1:24,000-scale National Hydrography Dataset flowlines. Lines having attribute PerCode = 1 represent model grid cells having 7Q2 flow estimates between 0.1 cubic feet per second (ft3/s) and 0.1 minus the standard error for the applicable regional regression equation. Lines having attribute PerCode = 2 represent model grid cells having 7Q2 flow estimates between 0.1 ft3/s and 0.1 plus the standard error for the applicable regional regression equation. Lines having attribute PerCode = 3 represent model grid cells having 7Q2 flow estimates greater than 0.1 ft3/s plus the standard error for the applicable regional regression equation. These three categories of lines indicate approximate levels of uncertainty in the model results, with lines having PerCode = 1 representing the most uncertainty, and lines having PerCode = 3 representing the least uncertainty with respect to representing a perennial stream.

Perennial streams in Idaho have been modeled using regression equations for 7-day, 2-year low flows (7Q2) described in Wood and others (2009, U.S. Geological Survey Scientific Investigations Report 2009-5015). The model produces "synthetic" streams based on 10-meter resolution digitial elevation models that have been processed to agree closely with 1:24,000-scale National Hydrography Dataset flowlines. See Larger_Work_Citation report text for a complete description of the modeling process. In this dataset, the synthetic stream lines have been indexed to the NHDPlus Version 01_02 (schema version 1, data version 2). Points along the synthetic streams where 7Q2 model estimates exceeded 0.1 cubic feet per second were snapped to the NHDPlus 1:100,000-scale flowlines, and then traced downstream using the NHDPlus network. The data are presented in the form of a dBase-format event table. The traced line events correspond to synthetic stream lines having PerCode values of 2 or 3.

Perennial streams in Idaho have been modeled using regression equations for 7-day, 2-year low flows (7Q2) described in Wood and others (2009, U.S. Geological Survey Scientific Investigations Report 2009-5015). The model produces "synthetic" streams based on 10-meter resolution digitial elevation models that have been processed to agree closely with 1:24,000-scale National Hydrography Dataset flowlines. See Larger_Work_Citation report text for a complete description of the modeling process. In this dataset, the synthetic stream lines have been indexed to the NHDPlus Version 01_02 (schema version 1, data version 2). Points along the synthetic streams where 7Q2 model estimates exceeded 0.1 cubic feet per second were snapped to the NHDPlus 1:100,000-scale flowlines, and then traced downstream using the NHDPlus network. The data are presented in the form of a dBase-format event table. The traced line events correspond to synthetic stream lines having PerCode values of 2 or 3.

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)

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)

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).

These datasets consist of a workspace (folder) containing a collection of gridded datasets plus a personal geodatabase containing several vector datasets. These datasets are designed to be used with the ArcHydro Tools, developed by ESRI in partnership with the U.S. Geological Survey, StreamStats Development Team. The datasets, together with the ArcHydro Tools, allow users to delineate watersheds and compute several watershed characteristics. The datasets are distributed in folders named for the 8-digit Hydrologic Unit Code (HUC) each covers. The data structure is the same for each HUC.

These datasets consist of a workspace (folder) containing a collection of gridded datasets plus a personal geodatabase containing several vector datasets. These datasets are designed to be used with the ArcHydro Tools, developed by ESRI in partnership with the U.S. Geological Survey, StreamStats Development Team. The datasets, together with the ArcHydro Tools, allow users to delineate watersheds and compute several watershed characteristics. The datasets are distributed in folders named for the 8-digit Hydrologic Unit Code (HUC) each covers. The data structure is the same for each HUC.

This data release contains results of a study investigating changes in streamflow seasonality associated with hydroclimatic variability in the north-central United States, including nine States (Illinois, Iowa, Michigan, Minnesota, Missouri, Montana, North Dakota, South Dakota, and Wisconsin). Peak-flow records from unregulated U.S. Geological Survey streamgages were used to evaluate changes in streamflow seasonality over 75-, 50-, and 30-year trend periods through water year 2020. The streamgages in each of the nine states used in the analysis and the results of the seasonal characteristics and statistical analyses are provided in tabular form (in csv file format) in file "Results.zip" under "Attached Files" below.