This metadata record describes mean seasonal time-step estimates of daily streamflow and daily baseflow, and total and baseflow estimates of loads of total nitrogen, total phosphorus, and total suspended solids at surface-water stations in the southeastern United States for the period 2001-14. Streamflow and load estimates described in this data release were obtained using the Fluxmaster approach described in Saad and others (2019). Saad, D.A., Schwarz, G.E., Argue, D.M., Anning, D.W., Ator, S.W., Hoos, A.B., Preston, S.D., Robertson, D.M., and Wise, D.R., 2019, Estimates of long-term mean daily streamflow and annual nutrient and suspended-sediment loads considered for use in regional SPARROW models of the conterminous United States, 2012 base year: U.S. Geological Survey Scientific Investigations Report 2019-5069, 51 p., https://doi.org/10.3133/sir20195069.

Estimated seasonal total nitrogen and total phosphorus loads during 1999 through 2020 in selected streams of the conterminous United States and water-quality and stream flow data used to generate those estimates are presented in this dataset. Loads were generated as part of the Integrated Water-Availability Assessment (IWAA) Program of the U.S. Geological Survey (www.usgs.gov/mission-areas/water-resources/science/integrated-water-availability-assessments#overview) using Fluxmaster (Schwarz and others, 2006, https://doi.org/10.3133/tm6B3) and Weighted Regression on Time, Discharge, and Season (WRTDS) (Hirsch and De Cicco, 2015, https://doi.org/10.1016/j.envsoft.2015.07.017). Loads were estimated initially for the Illinois River Basin (IRB) and later for the wider conterminous United States (including the IRB). Along with the water-quality data, streamflow data, and estimated nitrogen and phosphorus loads, this release also includes computer code that can be run to recreate the load estimates or modified for similar applications.

This USGS data release presents tabular data of daily and annual (for the 9-month period March 1 through November 30) estimates of concentrations and fluxes of total and dissolved phosphorus, total nitrogen, chloride, and total suspended solids for 18 monitored tributaries of Lake Champlain. Daily estimates generally cover the period March 1990 through November 2014 and annual estimates 1990 through 2014, although dates vary by constituent and tributary, depending on availability of raw data. The dataset consists of 6 items: 1. Annual (9-month) estimates of concentration and flux (tabular dataset); 2. Daily estimates of concentration and flux of total phosphorus (tabular dataset); 3. Daily estimates of concentration and flux of dissolved phosphorus (tabular dataset); 4. Daily estimates of concentration and flux of total nitrogen (tabular dataset); 5. Daily estimates of concentration and flux of chloride (tabular dataset); 6. Daily estimates of concentration and flux of total suspended solids (tabular dataset). These data support the following publication: Medalie, L., 2016, Concentration, Flux, and Trend Estimates with Uncertainty for Nutrients, Chloride, and Total Suspended Solids in Tributaries of Lake Champlain, 1990–2014: U.S. Geological Survey Open-File Report 2016–1200, 24 p., https://dx.doi.org/10.3133/ofr20161200.

This USGS data release presents tabular data of daily and annual (for the 9-month period March 1 through November 30) estimates of concentrations and fluxes of total and dissolved phosphorus, total nitrogen, chloride, and total suspended solids for 18 monitored tributaries of Lake Champlain. Daily estimates generally cover the period March 1990 through November 2014 and annual estimates 1990 through 2014, although dates vary by constituent and tributary, depending on availability of raw data. The dataset consists of 6 items: 1. Annual (9-month) estimates of concentration and flux (tabular dataset); 2. Daily estimates of concentration and flux of total phosphorus (tabular dataset); 3. Daily estimates of concentration and flux of dissolved phosphorus (tabular dataset); 4. Daily estimates of concentration and flux of total nitrogen (tabular dataset); 5. Daily estimates of concentration and flux of chloride (tabular dataset); 6. Daily estimates of concentration and flux of total suspended solids (tabular dataset). These data support the following publication: Medalie, L., 2016, Concentration, Flux, and Trend Estimates with Uncertainty for Nutrients, Chloride, and Total Suspended Solids in Tributaries of Lake Champlain, 1990–2014: U.S. Geological Survey Open-File Report 2016–1200, 24 p., https://dx.doi.org/10.3133/ofr20161200.

The United States Geological Survey’s (USGS) SPAtially Referenced Regressions On Watershed attributes (SPARROW) model was developed to aid in the interpretation of monitoring data and simulate water-quality conditions in streams across large spatial scales. SPARROW is a hybrid empirical/process-based mass balance model that can be used to estimate the major sources and environmental factors that affect the long-term supply, transport, and fate of contaminants in streams. The spatially explicit model structure is defined by a river reach network coupled with contributing catchments. The model is calibrated by statistically relating watershed sources and transport-related properties to monitoring-based streamflow and water-quality load estimates. Streamflow and load estimates considered for use in regional SPARROW model applications (2012 base year) are described in Saad and others, 2019 (https://dx.doi.org/10.3133/sir20195069). Load estimation methods described in this report include the Beale Ratio Estimator and Fluxmaster models. This USGS data release contains all of the input and output files necessary to reproduce the load estimates considered for inclusion in the 2012 regional SPARROW models. Data preparation for input to the load estimation models is also fully described in the above-mentioned report.

The United States Geological Survey’s (USGS) SPAtially Referenced Regressions On Watershed attributes (SPARROW) model was developed to aid in the interpretation of monitoring data and simulate water-quality conditions in streams across large spatial scales. SPARROW is a hybrid empirical/process-based mass balance model that can be used to estimate the major sources and environmental factors that affect the long-term supply, transport, and fate of contaminants in streams. The spatially explicit model structure is defined by a river reach network coupled with contributing catchments. The model is calibrated by statistically relating watershed sources and transport-related properties to monitoring-based streamflow and water-quality load estimates. Streamflow and load estimates considered for use in regional SPARROW model applications (2012 base year) are described in Saad and others, 2019 (https://dx.doi.org/10.3133/sir20195069). Load estimation methods described in this report include the Beale Ratio Estimator and Fluxmaster models. This USGS data release contains all of the input and output files necessary to reproduce the load estimates considered for inclusion in the 2012 regional SPARROW models. Data preparation for input to the load estimation models is also fully described in the above-mentioned report.

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.

This USGS data release contains long-term mean annual total nitrogen and total phosphorus load estimates, and the model coefficients used to obtain the load estimates, for streams in the Midwest Region of the United States. The loads were estimated using the Fluxmaster program (Schwarz and others, 2006, https://pubs.usgs.gov/tm/2006/tm6b3) with a 5-parameter model and detrending to 2012 following the methods described in Saad and others, 2011 (https://doi.org/10.1111/j.1752-1688.2011.00575.x). A subset of these load estimates are described in Robertson and Saad, 2021 (https://doi.org/10.1111/1752-1688.12905) and were used to evaluate differences in load estimates in the Mississippi/Atchafalaya River Basin based on this method and the methods described in Saad and others, 2019 (https://dx.doi.org/10.3133/sir20195069). The flow and water-quality input files necessary to reproduce the load estimates included in this data release can be found in Saad and others, 2019 (https://doi.org/10.5066/F7DN436B).

This USGS data release contains long-term mean annual total nitrogen and total phosphorus load estimates, and the model coefficients used to obtain the load estimates, for streams in the Midwest Region of the United States. The loads were estimated using the Fluxmaster program (Schwarz and others, 2006, https://pubs.usgs.gov/tm/2006/tm6b3) with a 5-parameter model and detrending to 2012 following the methods described in Saad and others, 2011 (https://doi.org/10.1111/j.1752-1688.2011.00575.x). A subset of these load estimates are described in Robertson and Saad, 2021 (https://doi.org/10.1111/1752-1688.12905) and were used to evaluate differences in load estimates in the Mississippi/Atchafalaya River Basin based on this method and the methods described in Saad and others, 2019 (https://dx.doi.org/10.3133/sir20195069). The flow and water-quality input files necessary to reproduce the load estimates included in this data release can be found in Saad and others, 2019 (https://doi.org/10.5066/F7DN436B).