Hydrologic indicator statistics were computed for 82 selected surface water sites located throughout Minnesota using daily streamflow data from the U.S. Geological Survey (USGS) National Water Information System (NWIS). The 187 hydrologic indicator statistics were computed in RStudio version 3.5.0 using the EflowStats version 5.0.0 (Mills and Blodgett, 2017) and NWCCompare version 5.0 (Blodgett, 2017). The computed hydrologic indicator statistics encompass the five components of hydrologic conditions: magnitude, frequency, duration, timing, and rate of change. Magnitude is the amount of water moving past a fixed location in a given unit of time. Frequency refers to how often streamflows above a given magnitude recur over a specified time interval. Duration is the period of time associated with a specific streamflow condition. Timing refers to the regularity with which streamflows of a given magnitude occur, and rate of change refers to how quickly the magnitude of streamflow changes (Poff and others, 1997). Site selection was based on sites previously selected in three other studies evaluating long-term streamflow records for trends (Novatny and Stefan, 2007; Peterson, Nieber, and Kanivetsky, 2011; Ziegeweid et.al, 2015). Nontrend sites were shown to not have trends in streamflow that were not related to precipitation. Hydrologic indicator statistics were computed for two periods: 1) the pre-period from 10-1-1944 through 9-30-1979 and 2) the post-period from 10-1-1980 through 9-30-2015. Exact dates of the start of trends varied among sites, but 1980 was the selected cutoff period based on an approximation of the largest cluster and on other anecdotal evidence of changes in farming practices. Both categories also had at least 10 water years with complete streamflow data. Blodgett, D., 2017, NWCCompare: Returns NWC comparison stats for two daily data sets version 5.0, https://github.com/USGS-R/NWCCompare. Mills, J., and Blodgett, D., 2017, EflowStats: Hydrologic Indicator and Alterations Stats version 5.0.0, https://github.com/USGS-R/EflowStats. Novotny, E.V., and Stefan, H.G., 2007, Stream flow in Minnesota: Indicator of climate change, Journal of Hydrology 334: 319-333. Peterson, H.M., Nieber, J.L., and Kanivetsky, R., 2011, Hydrologic regionalization to assess anthropogenic changes, Journal of Hydrology 408: 212-225. Ziegeweid, J.R., Lorenz, D.L., Sanocki, C.A., and Czuba, C.R., 2015, Methods for estimating flow-duration curve and low-flow frequency statistics for ungaged locations on small streams in Minnesota: U.S. Geological Survey Scientific Investigations Report 2015–5170, 23 p., http://dx.doi.org/10.3133/sir20155170.

The U.S. Geological Survey (USGS) and the Minnesota Pollution Control Agency (MPCA) conducted a cooperative study to develop linear regression models that quantify relations among 173 hydrologic explanatory metrics in five categories (duration, frequency, magnitude, rate-of-change, and timing) computed from streamgage records and 132 biological response metrics in six categories (composition, habitat, life history, reproductive, tolerance, trophic) computed from fish community samples collected from the 1996-2015 water years (WYs). In addition, linear relations were quantified between hydrologic metrics, fish-based indices of biotic integrity (FIBI) scores, and FIBI scores normalized to the impairment threshold of the corresponding stream class (FIBI_BCG4), resulting in a total of 134 regression equations per hydrologic dataset. Three hydrologic datasets were used to examine relations between altered hydrology and fish community responses at different temporal scales. First, the period-of-record (POR) dataset was created by computing hydrologic metrics using all complete WYs of streamflow record (1945WY and later) and ending with the WY of corresponding biological sample collection. Next, datasets representing long-term changes (LTC) and short-term changes (STC) in hydrology were created using ratios of hydrologic metrics computed for different time periods. The LTC ratios were obtained by dividing hydrologic metrics computed from available streamflow records from the 1981WY through the WY of biological sample collection by hydrologic metrics computed from available streamflow records during the 1945-79WYs. The STC ratios were obtained by dividing hydrologic metrics computed from the last 10 water years up to the WY of biological sample collection by hydrologic metrics computed from the POR for each streamgage. The POR, LTC, and STC datasets included 54, 39, and 48 hydrologic and biological site pairs, respectively. Results of regression analyses are described in a companion publication (https://doi.org/TBD). A subset of the best regression models based on pseudo-R2 values is published in the companion publication, but all 134 final regression models for each of the three datasets are published in this data release. Model archives of best subset and left-censored linear regression models are provided and include readme files, raw data files, R scripts used to compute regression analyses, and model outputs. Daily streamflow data were retrieved from the National Water Information System (NWIS; at https://waterdata.usgs.gov/nwis). A minimum of 10 years of complete daily streamflow record was required for computing hydrologic metrics to pair with biological metrics. RStudio (version 3.5.0) and the EflowStats (version 5.0.0) and NWCCompare (version 5.0) packages were used to compute hydrologic metrics. Biological metrics used in described datasets were computed by and obtained from the MPCA (MPCA, 2016). Similar hydrologic statistics were computed using the EflowStats package and published in a previous data release (https://doi.org/10.5066/P9ND1NPT).

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 map service represents modeled streamflow metrics from the mid-century time period (2030-2059) in the United States. In addition to standard NHD attributes, the streamflow datasets include metrics on mean daily flow (annual and seasonal), flood levels associated with 1.5-year, 10-year, and 25-year floods; annual and decadal minimum weekly flows and date of minimum weekly flow, center of flow mass date; baseflow index, and average number of winter floods. These files and additional information are available on the project website, https://www.fs.usda.gov/rm/boise/AWAE/projects/modeled_stream_flow_metrics.shtml. Streams without flow metrics (null values) were removed from this dataset to improve display speed; to see all stream lines, use an NHD flowline dataset.,

This map service represents modeled streamflow metrics from the historical time period (1977-2006) in the United States. In addition to standard NHD attributes, the streamflow datasets include metrics on mean daily flow (annual and seasonal), flood levels associated with 1.5-year, 10-year, and 25-year floods; annual and decadal minimum weekly flows and date of minimum weekly flow, center of flow mass date; baseflow index, and average number of winter floods.�These files and additional information are available on the project� website,�https://www.fs.usda.gov/rm/boise/AWAE/projects/modeled_stream_flow_metrics.shtml. Streams without flow metrics (null values) were removed from this dataset to improve display speed; to see all stream lines, use an NHD flowline dataset.,

The U.S. Geological Survey (USGS), in cooperation with the Illinois Center for Transportation and the Illinois Department of Transportation, prepared hydro-conditioned geographic information systems (GIS) layers for use in the Illinois StreamStats application. These data were used to delineate drainage basins and compute basin characteristics for updated peak flow and flow duration regression equations for Illinois. This dataset consists of raster grid files for elevation (dem), flow accumulation (fac), flow direction (fdr), and stream definition (str900) for each 8-digit Hydrologic Unit Code (HUC) area in Illinois merged into a single dataset. There are 51 full or partial HUC 8s represented by this data set: 04040002, 05120108, 05120109, 05120111, 05120112, 05120113, 05120114, 05120115, 05140202, 05140203, 05140204, 05140206, 07060005, 07080101, 07080104, 07090001, 07090002, 07090003, 07090004, 07090005, 07090006, 07090007, 07110001, 07110004, 07110009, 07120001, 07120002, 07120004 (0712003 was combined into this HUC), 07120005, 07120006, 07120007, 07130001, 07130002, 07130003, 07130004, 07130005, 07130006, 07130007, 07130008, 07130009, 07130010, 07130011, 07130012, 07140101, 07140105, 07140106, 07140108, 07140201, 07140202, 07140203, and 07140204.

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.

A comprehensive study to evaluate water-quality trends in the International Souris River Basin, Saskatchewan and Manitoba, Canada and North Dakota, United States was completed by the U.S. Geological Survey (USGS) in cooperation with the International Joint Commission and International Souris River Board. This child page contains seven csv files, site_flow, which contain daily streamflow values for each site. Each file includes a station identifier, date of observation, measured value of streamflow and qualifier code for the measured value. The format of the csv file (date format and column headings) is designed to meet the specific requirements of file format for R-QWTREND. If csv files are opened directly in excel, the format of the data can change. To ensure the data are in the proper format for R-QWTREND, files should be opened in a text editor. The "site" in site_flow can be cross-referenced to the main report by navigating to the file siteinfo.table.csv.

A comprehensive study to evaluate water-quality trends in the International Souris River Basin, Saskatchewan and Manitoba, Canada and North Dakota, United States was completed by the U.S. Geological Survey (USGS) in cooperation with the International Joint Commission and International Souris River Board. This child page contains seven csv files, site_flow, which contain daily streamflow values for each site. Each file includes a station identifier, date of observation, measured value of streamflow and qualifier code for the measured value. The format of the csv file (date format and column headings) is designed to meet the specific requirements of file format for R-QWTREND. If csv files are opened directly in excel, the format of the data can change. To ensure the data are in the proper format for R-QWTREND, files should be opened in a text editor. The "site" in site_flow can be cross-referenced to the main report by navigating to the file siteinfo.table.csv.

A comprehensive study to evaluate water-quality trends in the International Souris River Basin, Saskatchewan and Manitoba, Canada and North Dakota, United States was completed by the U.S. Geological Survey (USGS) in cooperation with the International Joint Commission and International Souris River Board. This child page contains seven csv files, site_flow, which contain daily streamflow values for each site. Each file includes a station identifier, date of observation, measured value of streamflow and qualifier code for the measured value. The format of the csv file (date format and column headings) is designed to meet the specific requirements of file format for R-QWTREND. If csv files are opened directly in excel, the format of the data can change. To ensure the data are in the proper format for R-QWTREND, files should be opened in a text editor. The "site" in site_flow can be cross-referenced to the main report by navigating to the file siteinfo.table.csv.