This U.S. Geological Survey (USGS) data release includes locations for 12,422 USGS streamgages as indexed along the network of streams (flowlines) in NHDPlus Version 2.1 (NHDPlus v2, Moore and Dewald, 2016). The dataset is one of two datasets developed for the Streamgage Watershed InforMation (SWIM) project. This dataset, which is referred to as “SWIM streamgage locations,” was created in support of the second dataset of basin characteristics and disturbance indexes. The streamgages are located in the conterminous United States and have a minimum record length of 20 years of daily streamflow values or at least 20 years of peak flows (USGS National Water Information System (NWIS) database, U.S. Geological Survey, 2016). This dataset has a total of 13,248 streamgages, 826 of which could not be indexed to NHDPlus v2.1. A custom ArcGIS tool was programmed to conduct linear referencing, which moved each point representing a streamgage to intersect with the nearest flowline and calculated the measure along the segment (expressed as a percentage from its downstream end). The tool then performed a series of automated tests to identify potentially inaccurate locations that were, in turn, individually checked. Comments collected during multiple levels of review were retained in raw form to aid future decisions about the accuracy of the streamgage locations along the medium-resolution (1:100,000-scale) NHDPlus stream segments. The results include the unique flowline identifier (COMID) and measure along the flowline, the reach code and measure along its reach (stream feature that consists of one or more flowlines), review notes, plus the latitude and longitude of the stream-referenced location for each streamgage. This designated position along the NHDPlus network may also be referred to as the hydrographic address of the streamgage. References: Falcone, J.A., 2011, GAGES-II: Geospatial Attributes of Gages for Evaluating Streamflow: U.S. Geological Survey dataset, https://doi.org/10.3133/70046617 Moore, R.B., and Dewald, T.G., 2016, The Road to NHDPlus — Advancements in digital stream networks and associated catchments: Journal of the American Water Resources Association, https://doi.org/10.1111/1752-1688.12389 U.S. Geological Survey, 2016, USGS water data for the Nation: U.S. Geological Survey National Water Information System database, accessed October 2016, at https://doi.org/10.5066/F7P55KJN

This dataset contains statistical descriptions of observed daily-mean streamflow for 956 sites in the southeast United States. For each site, statistical descriptions are provided according to decade for up to six decades, beginning in 1950 (1950-59 calendar years) and ending with 2000 (2000 - 2009 calendar years) with no more than 7 missing values per year in total (continuous or noncontinuous). There are 40 statistical descriptions including 28 flow-duration curve values, 8 L-moments, and 4 describing the minimum, maximum, median flow for days not equal to zero, and number of zero-flow days. Site information is provided by decade - the number of rows per site varies from 1 to 6 depending on the number of decades with observed record available. This information was used as the response variable(s) for statistical models for estimating the same characteristics at nearly 10,000 ungaged locations throughout the southeast United States. The dataset has been provided as a shapefile and a comma-delimited file. The comma-delimited file is an exact copy of the attribute table of the shapefile.

This dataset contains statistical descriptions of observed daily-mean streamflow for 956 sites in the southeast United States. For each site, statistical descriptions are provided according to decade for up to six decades, beginning in 1950 (1950-59 calendar years) and ending with 2000 (2000 - 2009 calendar years) with no more than 7 missing values per year in total (continuous or noncontinuous). There are 40 statistical descriptions including 28 flow-duration curve values, 8 L-moments, and 4 describing the minimum, maximum, median flow for days not equal to zero, and number of zero-flow days. Site information is provided by decade - the number of rows per site varies from 1 to 6 depending on the number of decades with observed record available. This information was used as the response variable(s) for statistical models for estimating the same characteristics at nearly 10,000 ungaged locations throughout the southeast United States. The dataset has been provided as a shapefile and a comma-delimited file. The comma-delimited file is an exact copy of the attribute table of the shapefile.

This dataset represents 19,031 basin boundaries and their streamgage locations for the U.S. Geological Survey's (USGS) active and historical streamgages from the published dataset of Stewart and others (2006) and its subsequent updates (D.W. Stewart, USGS, written commun., 2011). Only the basin boundaries that were delineated within 15 percent of the basin area reported in the National Water Information System (NWIS) were included in this dataset. This dataset only includes streamgage basins in the lower 48 states and not in Alaska, Hawaii, or Puerto Rico. The basin boundaries and streamgage locations are provided in 18 shapefiles separated by 2-digit Hydrologic Unit Code. The USGS streamgage station's identification number attached to each delineated polygon can be linked to the attribute data found in Stewart and others (2006). The delineated watersheds were made from digital elevation models found in the NHDPlus data suite (version 1, 2006) and based on gage locations provided by Stewart and others (2006). These basins have been used in several USGS studies such as James Falcone's "GAGES-II: Geospatial Attributes of Gages for Evaluating Streamflow" (2011) and Xiaodong Jian and others, "WaterWatch-Maps, Graphs, and Tables of Current, Recent, and Past Streamflow Conditions " (2008).

This dataset represents 19,031 basin boundaries and their streamgage locations for the U.S. Geological Survey's (USGS) active and historical streamgages from the published dataset of Stewart and others (2006) and its subsequent updates (D.W. Stewart, USGS, written commun., 2011). Only the basin boundaries that were delineated within 15 percent of the basin area reported in the National Water Information System (NWIS) were included in this dataset. This dataset only includes streamgage basins in the lower 48 states and not in Alaska, Hawaii, or Puerto Rico. The basin boundaries and streamgage locations are provided in 18 shapefiles separated by 2-digit Hydrologic Unit Code. The USGS streamgage station's identification number attached to each delineated polygon can be linked to the attribute data found in Stewart and others (2006). The delineated watersheds were made from digital elevation models found in the NHDPlus data suite (version 1, 2006) and based on gage locations provided by Stewart and others (2006). These basins have been used in several USGS studies such as James Falcone's "GAGES-II: Geospatial Attributes of Gages for Evaluating Streamflow" (2011) and Xiaodong Jian and others, "WaterWatch-Maps, Graphs, and Tables of Current, Recent, and Past Streamflow Conditions " (2008).

This tabular data set represents base flow index (BFI) compiled for two spatial components of the NHDPlus version 2 data suite (NHDPlusv2) for the conterminous United States; 1) individual reach catchments and 2) reach catchments accumulated upstream through the river network. This dataset can be linked to the NHDPlus version 2 data suite by the unique identifier COMID. The source data is the "Base-flow index grid for the conterminous United States" produced by the United States Geological Survey (Wolock, 2003). Units are percent. Base flow is the component of streamflow that can be attributed to ground-water discharge into streams. The BFI is the ratio of base flow to total flow, expressed as a percentage. Reach catchment information characterizes data at the local scale. Reach catchments accumulated upstream through the river network characterizes cumulative upstream conditions. Network-accumulated values are computed using two methods, 1) divergence-routed and 2) total cumulative drainage area. Both approaches use a modified routing database to navigate the NHDPlus reach network to aggregate (accumulate) the metrics derived from the reach catchment scale. (Schwarz and Wieczorek, 2018).

This dataset includes four tables related to annual trends in streamflow metrics at 599 reference streamgages in the conterminous United States for the period 1955-2014. Reference streamgages are defined here as gages with drainage basins that are minimally impacted by anthropogenic effects such as reservoirs or urbanization. The four tables are: 1) computed annual values for 16 streamflow metrics, 2) trend estimates for the 16 streamflow metrics for the period 1955-2014, 3) metric names and definitions, and 4) location information (latitude and longitude) for the 599 sites. The computed annual values for the 16 streamflow metrics are: low flow magnitude, low flow frequency, low flow duration, high flow magnitude, high flow frequency, high flow duration, skew, daily rises, Spring low flow percentage, Spring high flow percentage, Summer low flow percentage, Summer high flow percentage, Fall low flow percentage, Fall high flow percentage, Winter low flow percentage, and Winter high flow percentage. The annual flow metrics were estimated by Eng and others (2017) from daily streamflow records at the 599 reference streamgages. Sen slope trend values and confidence intervals for the 16 flow metrics for the period 1955-2014 were computed from the annual time series using the non-parametric Theil-Sen approach (Sen, P., 1968). In addition to the Sen slope, the median value for each metric for the period 1955-2014, the percentage change in each metric over the period 1955-2014, and a percentage change class for each metric also are reported.

This metadata record documents two comma separated text files of average daily fresh-water withdrawal amounts by NHDPlus v2.1 catchment (COMID) within the conterminous United States for calendar year 2010. County-level reported estimated use of water are specifically reported as groundwater and surface water and are allotted to catchments by a sum of the catchment based on evenly distributing the county total across the number of county land-area pixels. All values are reported as gallons per day. Source county-level data were acquired from Estimated use of water in the United States in 2010 (Maupin and others, 2014; available at https://dx.doi.org/10.3133/cir1405). These datasets can be linked to the NHDPlus version 2.1 data suite by the unique identifier COMID (or comid).

This metadata record documents two comma separated text files of average daily fresh-water withdrawal amounts by NHDPlus v2.1 catchment (COMID) within the conterminous United States for calendar year 2010. County-level reported estimated use of water are specifically reported as groundwater and surface water and are allotted to catchments by a sum of the catchment based on evenly distributing the county total across the number of county land-area pixels. All values are reported as gallons per day. Source county-level data were acquired from Estimated use of water in the United States in 2010 (Maupin and others, 2014; available at https://dx.doi.org/10.3133/cir1405). These datasets can be linked to the NHDPlus version 2.1 data suite by the unique identifier COMID (or comid).