Water samples were collected by the USGS National Water Quality Program (NWQP) Southeastern Stream Quality Assessment (SESQA) from 76 perennial, wadeable (less than 10 m width and 1 m depth at base-flow) headwater stream sites in watersheds with varying degrees of urban land use in four states. Dataset includes sample site locations and information, water sample nutrient concentrations and statistics analyses, and corresponding watershed land-use-land-cover data and data dictionary.

Filtered water samples were collected by the USGS National Water Quality Program (NWQP) Southeastern Stream Quality Assessment (SESQA) from 59 perennial, wadeable (less than 10 m width and 1 m depth at base-flow) headwater stream sites in watersheds with varying degrees of urban land use in four states. Dataset includes sample site locations and information, analytical method information, water sample pharmaceutical concentrations and summary statistics, and corresponding watershed land-use-land-cover data and data dictionary.

Filtered water samples were collected by the USGS National Water Quality Program (NWQP) Southeastern Stream Quality Assessment (SESQA) from 59 perennial, wadeable (less than 10 m width and 1 m depth at base-flow) headwater stream sites in watersheds with varying degrees of urban land use in four states. Dataset includes sample site locations and information, analytical method information, water sample pharmaceutical concentrations and summary statistics, and corresponding watershed land-use-land-cover data and data dictionary.

This dataset represents density of all wastewater treatment plants within individual, local NHDPlusV2 catchments and upstream, contributing watersheds. Measured as number/ km2.

This dataset represents density of all wastewater treatment plants within individual, local NHDPlusV2 catchments and upstream, contributing watersheds. Measured as number/ km2.

The U.S. Geological Survey (USGS) developed a spatial water-quality model called SPAtially Referenced Regressions On Watershed attributes (SPARROW) to estimate the major sources and environmental factors that affect the long-term supply, transport, and fate of contaminants in the Nation’s streams. The SPARROW model relates in-stream water-quality data to spatially referenced characteristics of watersheds, including contaminant sources and factors influencing terrestrial and aquatic transport. Based on SPARROW modeling, one of the main nutrient sources to streams is point-source facilities such as municipal waste-water treatment plants that discharge directly to streams. This dataset was developed to assist with SPARROW models developed to assess supply, transport and fate of total nitrogen and phosphorous in streams of the conterminous United States (2012). This dataset documents discharge information from point sources in the conterminous United States and was obtained from the EPA Integrated Compliance Information System (ICIS) and Permit Compliance System (PCS). When available, nutrient concentrations were used to calculate point source loads. However, in many cases measured concentration data were not available in the ICIS or PCS data base and so “typical pollutant concentrations” (TPC’s) were developed using data from similar facilities. A new method for calculating TPC’s was implemented that allows varying amounts of nutrient concentration data and/or varying numbers of facilities to determine TPC’s. This dataset contains the EPA facility, flow, and concentration data and all updates to the data, along with the TPC tables and resultant total nitrogen and phosphorous loads calculated from the input datasets.

The U.S. Geological Survey (USGS) developed a spatial water-quality model called SPAtially Referenced Regressions On Watershed attributes (SPARROW) to estimate the major sources and environmental factors that affect the long-term supply, transport, and fate of contaminants in the Nation’s streams. The SPARROW model relates in-stream water-quality data to spatially referenced characteristics of watersheds, including contaminant sources and factors influencing terrestrial and aquatic transport. Based on SPARROW modeling, one of the main nutrient sources to streams is point-source facilities such as municipal waste-water treatment plants that discharge directly to streams. This dataset was developed to assist with SPARROW models developed to assess supply, transport and fate of total nitrogen and phosphorous in streams of the conterminous United States (2012). This dataset documents discharge information from point sources in the conterminous United States and was obtained from the EPA Integrated Compliance Information System (ICIS) and Permit Compliance System (PCS). When available, nutrient concentrations were used to calculate point source loads. However, in many cases measured concentration data were not available in the ICIS or PCS data base and so “typical pollutant concentrations” (TPC’s) were developed using data from similar facilities. A new method for calculating TPC’s was implemented that allows varying amounts of nutrient concentration data and/or varying numbers of facilities to determine TPC’s. This dataset contains the EPA facility, flow, and concentration data and all updates to the data, along with the TPC tables and resultant total nitrogen and phosphorous loads calculated from the input datasets.

Nitrogen (N), phosphorus (P), and suspended-sediment (SS) loads, in Fairfax County, Virginia streams have been calculated using monitoring data from five intensively monitored watersheds for the period from water year (October - September) 2008-2017. Nutrient and suspended-sediment loads were computed using a surrogate (multiple-linear regression) approach with lab analyzed N, P, and SS samples as the response variable and basic water-quality parameters (e.g. turbidity, specific conductance, pH, water temperature), streamflow, and time and seasonal terms that could be measured continuously as predictor (surrogate) variables. The load results represent the total mass of N, P, and SS that was exported from each of the Fairfax County watersheds. Trends in N, P, SS concentrations, as well as basic water-quality parameters including turbidity, water temperature, dissolved oxygen, specific conductance, and pH have been calculated using both non-flow-normalized and flow-normalized Seasonal Kendall tests at 14 monitoring stations in Fairfax County, Virginia for the period beginning April 2008 and ending March 2018. Flow-normalized trends were used to integrate out the effect of annual streamflow variability on concentration (or unit value). Streamflow is an important driver of water-quality conditions; therefore, several datasets are provided describing a suite of annual streamflow metrics: streamflow volume/yield, flashiness, peak stage, baseflow index, stormflow index, and runoff ratio. Depending on the metric, data are provided from the 5 intensively monitored Fairfax County, VA watersheds, the entire 20-station Fairfax County monitoring network (5 intensively monitored + 15 trend only monitoring stations), and/or 3 reference stations that are part of the USGS Chesapeake Bay Non-Tidal Network (USGS Station IDs 01646000, 01654000, 01658500). Streamflow analyses were conducted on data collected in water years 2008-2017 for all Fairfax County monitoring stations as well as station ID 01658500, 1948-2017 for station ID 01654000, and 1946-2017 for 01646000. Benthic macroinvertebrate data were collected annually (waters years 2008 - 2017) by Fairfax County staff from each of the 20 monitoring stations. These data were used to explore trends in 20 biological metrics; the data used to calculate these trends are provided.

Nitrogen (N), phosphorus (P), and suspended-sediment (SS) loads, in Fairfax County, Virginia streams have been calculated using monitoring data from five intensively monitored watersheds for the period from water year (October - September) 2008-2017. Nutrient and suspended-sediment loads were computed using a surrogate (multiple-linear regression) approach with lab analyzed N, P, and SS samples as the response variable and basic water-quality parameters (e.g. turbidity, specific conductance, pH, water temperature), streamflow, and time and seasonal terms that could be measured continuously as predictor (surrogate) variables. The load results represent the total mass of N, P, and SS that was exported from each of the Fairfax County watersheds. Trends in N, P, SS concentrations, as well as basic water-quality parameters including turbidity, water temperature, dissolved oxygen, specific conductance, and pH have been calculated using both non-flow-normalized and flow-normalized Seasonal Kendall tests at 14 monitoring stations in Fairfax County, Virginia for the period beginning April 2008 and ending March 2018. Flow-normalized trends were used to integrate out the effect of annual streamflow variability on concentration (or unit value). Streamflow is an important driver of water-quality conditions; therefore, several datasets are provided describing a suite of annual streamflow metrics: streamflow volume/yield, flashiness, peak stage, baseflow index, stormflow index, and runoff ratio. Depending on the metric, data are provided from the 5 intensively monitored Fairfax County, VA watersheds, the entire 20-station Fairfax County monitoring network (5 intensively monitored + 15 trend only monitoring stations), and/or 3 reference stations that are part of the USGS Chesapeake Bay Non-Tidal Network (USGS Station IDs 01646000, 01654000, 01658500). Streamflow analyses were conducted on data collected in water years 2008-2017 for all Fairfax County monitoring stations as well as station ID 01658500, 1948-2017 for station ID 01654000, and 1946-2017 for 01646000. Benthic macroinvertebrate data were collected annually (waters years 2008 - 2017) by Fairfax County staff from each of the 20 monitoring stations. These data were used to explore trends in 20 biological metrics; the data used to calculate these trends are provided.

These data represent the National Nutrient Inventory's quantification of major inputs (farm fertilizer, urban fertilizer, livestock manure, human waste, deposition, biological crop nitrogen (N) fixation, and point source loads) and outputs (crop removal by harvest) of N and phosphorus (P) within individual local NHDPlusV2 catchments and contributing watersheds. The dataset also includes the following metrics derived from these inputs and outputs: legacy agricultural surplus, annual agricultural surplus, and total inputs. All metrics are available as an annual time series from 1987-2017, except for N deposition (1990-2017), P deposition (1997-2013), and point source loads (1978, 1980, 1982, 1984, 1986, 1988, 1990, 1992, 1996, 2000, 2004, 2008, 2012). StreamCatNNI metrics are in kilograms. For more information on National Nutrient Inventory metrics, see: https://www.epa.gov/water-research/national-nutrient-inventory-portfolio.