Incedental wastewater reuse from streams that receive discharges from Wastewater Treatment Facilities (WWTF) has the potential to be a significant contributor of Endocrine Disrupting Chemicals. An ArcGIS model of WWTFs, NHDPlus Version 2 stream networks (USGS and EPA 2012), and gage stations across the Shenandoah River watershed was created to calculate accumulated wastewater in percent of streamflow (ACCWW%) and Predicted Environmental Concentrations (PECs) of select constituents. Virginia and West Virginia Pollutant Discharge Elimination System (VPDES, WVPDES) discharge facilities, outfall locations, and stream gages were spatially joined to the nearest river segment. Wastewater inputs from outfall locations were summarized by river segment COMIDs (Common identifier). All wastewater discharge facility locations were verified with United States Environmental Protection Agency (EPA) Facility Registry Service. WWTFs were categorized as industrial or municipal based on the type of permit they were granted. Accumulated wastewater, ACCWW% and PECs were calculated using a python script. Maximum facility-capacity permitted wastewater discharge and 2015 average-annual wastewater discharge were used to calculate ACCWW% for mean-annual and mean-August streamflow conditions. PECs were only calculated for mean-annual streamflow and 2015 average-annual municipal discharges.

Treated effluent from wastewater treatment plants (WWTPs) contains contaminants not fully removed during the treatment process and that may pose environmental health risks when discharged to surface waters. This data release presents inputs for and results from a wastewater reuse model that used data compiled from several sources to calculate the following estimates for each non-tidal, non-coastline, initialized National Hydrography Dataset Version 2.1 (NHDPlus V2) stream segment in the Potomac River watershed: (1) accumulated wastewater as a percent of total streamflow (ACCWW%); and (2) predicted environmental concentrations (PECs, in micrograms per liter) of 69 municipal effluent-derived contaminants. ACCWW% values were calculated for mean-monthly and mean-annual streamflow conditions for both municipal (model results table: Table1_PotomacACCWW_municipal.csv) and industrial-plus-municipal effluent discharges (model results table: Table2_PotomacACCWW_municipal_plus_industrial.csv). PECs were calculated for mean-monthly and mean-annual streamflow conditions for municipal effluent discharges (model results tables: Table3_PotomacPECs.zip, containing comma separated value files of results for mean-monthly and mean-annual conditions). Model estimates at a stream reach of interest represent the combined total upstream wastewater discharges as well as direct discharges into the segment. Model input data included: (1) National Pollutant Discharge Elimination System-permitted facility outfall locations and 2016 average daily effluent discharges linked to a NHDPlus V2 stream Common Identifier (COMID) and facility-specific information on treatment levels and population served per capita (model input table: Table4_PotomacWWTPs.csv); (2) NHDPlus V2 stream geometry and hydrologic attributes (hydrosequence, startflag, terminalfl, divergence, fromnode, tonode, and Enhanced Runoff Method mean-monthly and mean-annual gage-adjusted streamflow and velocity, 1971-2000) (model input table: Table5_PotomacNHDPlusV2.1_flowlines_hydrology.csv); and (3) contaminant-specific data on consumption, fate, and transport compiled from literature sources or estimated from physicochemical properties (see: supplementary table in Larger Work Citation). In Table 4, where information on population served by the facility was missing, this value was estimated by standardizing to 100 gallons per capita per day. Information on population served was only acquired and estimated for municipal facilities. Where treatment level information was missing, the treatment level was assumed to be primary. Ninety-two percent of WWTPs have an assumed treatment as none was reported. R (version 4.0.4) and Python (version 2.7.16) scripts were used to summarize wastewater inputs from outfall locations by COMID and route and accumulate each wastewater and predicted contaminant loads while accounting for in-stream dilution and attenuation of contaminants. Any users of these data should review the entire metadata record and the associated manuscript (see Larger Work Citation). See 'Distribution liability' statements for more information.

Treated effluent from wastewater treatment plants (WWTPs) contains contaminants not fully removed during the treatment process and that may pose environmental health risks when discharged to surface waters. This data release presents inputs for and results from a wastewater reuse model that used data compiled from several sources to calculate the following estimates for each non-tidal, non-coastline, initialized National Hydrography Dataset Version 2.1 (NHDPlus V2) stream segment in the Potomac River watershed: (1) accumulated wastewater as a percent of total streamflow (ACCWW%); and (2) predicted environmental concentrations (PECs, in micrograms per liter) of 69 municipal effluent-derived contaminants. ACCWW% values were calculated for mean-monthly and mean-annual streamflow conditions for both municipal (model results table: Table1_PotomacACCWW_municipal.csv) and industrial-plus-municipal effluent discharges (model results table: Table2_PotomacACCWW_municipal_plus_industrial.csv). PECs were calculated for mean-monthly and mean-annual streamflow conditions for municipal effluent discharges (model results tables: Table3_PotomacPECs.zip, containing comma separated value files of results for mean-monthly and mean-annual conditions). Model estimates at a stream reach of interest represent the combined total upstream wastewater discharges as well as direct discharges into the segment. Model input data included: (1) National Pollutant Discharge Elimination System-permitted facility outfall locations and 2016 average daily effluent discharges linked to a NHDPlus V2 stream Common Identifier (COMID) and facility-specific information on treatment levels and population served per capita (model input table: Table4_PotomacWWTPs.csv); (2) NHDPlus V2 stream geometry and hydrologic attributes (hydrosequence, startflag, terminalfl, divergence, fromnode, tonode, and Enhanced Runoff Method mean-monthly and mean-annual gage-adjusted streamflow and velocity, 1971-2000) (model input table: Table5_PotomacNHDPlusV2.1_flowlines_hydrology.csv); and (3) contaminant-specific data on consumption, fate, and transport compiled from literature sources or estimated from physicochemical properties (see: supplementary table in Larger Work Citation). In Table 4, where information on population served by the facility was missing, this value was estimated by standardizing to 100 gallons per capita per day. Information on population served was only acquired and estimated for municipal facilities. Where treatment level information was missing, the treatment level was assumed to be primary. Ninety-two percent of WWTPs have an assumed treatment as none was reported. R (version 4.0.4) and Python (version 2.7.16) scripts were used to summarize wastewater inputs from outfall locations by COMID and route and accumulate each wastewater and predicted contaminant loads while accounting for in-stream dilution and attenuation of contaminants. Any users of these data should review the entire metadata record and the associated manuscript (see Larger Work Citation). See 'Distribution liability' statements for more information.

A wastewater reuse model was applied to the Upper Colorado River basin to assess the percent of accumulated wastewater (ACCWW%) from municipal and industrial wastewater treatment plants (WWTPs) in each initialized (that is, has an assigned hydrosequence number for flow-routing) National Hydrography Dataset Version 2.1 (NHDPlus V2.1) stream segment. Model inputs included (1) NHDPlus V2.1 stream geometry and hydrologic information (Table 1); (2) WWTP information, provided by the U.S. Environmental Protection Agency (Table 2), including average daily effluent discharges and outfall locations. Outfall locations were linked to the corresponding NHDPlus V2.1 stream segment receiving the effluent prior to calculating ACCWW%. ACCWW% values were calculated for years 2007 to 2020 using mean-monthly and mean-annual NHDPlus V2.1 gage-adjusted Enhanced Runoff Method streamflow estimates.

A wastewater reuse model was applied to the Upper Colorado River basin to assess the percent of accumulated wastewater (ACCWW%) from municipal and industrial wastewater treatment plants (WWTPs) in each initialized (that is, has an assigned hydrosequence number for flow-routing) National Hydrography Dataset Version 2.1 (NHDPlus V2.1) stream segment. Model inputs included (1) NHDPlus V2.1 stream geometry and hydrologic information (Table 1); (2) WWTP information, provided by the U.S. Environmental Protection Agency (Table 2), including average daily effluent discharges and outfall locations. Outfall locations were linked to the corresponding NHDPlus V2.1 stream segment receiving the effluent prior to calculating ACCWW%. ACCWW% values were calculated for years 2007 to 2020 using mean-monthly and mean-annual NHDPlus V2.1 gage-adjusted Enhanced Runoff Method streamflow estimates.

This data release contains measured streamflow data from U.S. Geological Survey (USGS) streamgages and reported wastewater data from wastewater treatment plants (WWTP) discharge monitoring reports (DMRs) within the Potomac River watershed between October 1, 2021 and September 30, 2024. Mean monthly streamflow data was obtained from 117 USGS streamgages (Table1_Streamgages.csv). Average monthly reported wastewater discharge volumes to surface water were obtained from National Pollutant Discharge Elimination System (NPDES) permits using the United States Environmental Protection Agency’s (USEPA) Environment and Compliance History Online (ECHO) database to obtain DMRs from the Integrated Compliance Information System National Pollutant Discharge Elimination System (ICIS-NPDES). Quality assurance procedures that were used to avoid inclusion of inaccurate data that can be reported on DMRs (Table2_WWTP_DMRs.csv) are documented within the Process Step fields of the metadata. At each streamgage the average monthly accumulated wastewater percentage (ACCWW) was calculated by dividing the total amount of reported wastewater upstream of the streamgage by the measured amount of streamflow (Table3_Streamgage_ACCWW.csv) following similar methods described in Miller and others (2024) and Barber and others (2025). The ACCWW calculations were computed monthly at each streamgage using reported total wastewater discharge, municipal wastewater discharge, and municipal-plus-industrial per- and polyfluoroalkyl substances (PFAS) wastewater discharge which includes municipal wastewater in addition to wastewater from industrial WWTPs that are potential PFAS handling industry sectors defined by the USEPA (2023). The term ‘municipal’ is used here to represent NPDES-permitted facilities with the Standard Industrial Classification code 4952 (‘sewerage systems’) and 'industrial' refers to permitted facilities with Standard Industrial Classification codes other than 4952. Monthly predicted environmental concentrations and constituent loads (i.e. mass fluxes) of eight PFAS and 14 pesticides were estimated at each streamgage following methodology presented by Barber and others (2025) and Miller and others (2024). Monthly PFAS loads were computed by multiplying the discharge volumes from municipal and industrial WWTPs that are potential PFAS handling industry sectors by the median PFAS concentrations measured and reported in Barber and others (2025). Monthly pesticide loads were computed by multiplying the discharge volumes from municipal WWTPs by the median pesticide concentrations reported in Miller and others (2024). Wastewater effluent concentrations from Miller and others (2024) and Barber and others (2025) are provided in Table4_Parameters.csv. Monthly predicted constituent loads from wastewater were summed from WWTPs that discharged to every National Hydrography Dataset Version 2.1 (NHDPlus V2; USEPA, 2012) stream segment Common Identifier (COMID) upstream of each streamgage, not including the COMID where the streamgage was located, to calculate the predicted monthly load at each streamgage (Table5_Streamgage_Parameter_Predictions.csv). Predicted monthly concentrations from wastewater were calculated by dividing the predicted monthly load by measured monthly streamflow at each streamgage (Table5_Streamgage_Parameter_Predictions.csv).

This data release presents calculated accumulated wastewater (ACCWW, as a percent of total streamflow) values for 43 National Hydrologic Dataset Version 2.1 (NHDPlus V2.1) stream segments coinciding with long-term smallmouth bass sampling locations (Table 1) in the Shenandoah River Watershed (encompassing parts of Virginia and West Virginia, USA). Values are calculated for quarter-year (Quarter 1 [Q1], January - March; Quarter 2 [Q2], April - June; Quarter 3 [Q3], July-September; Quarter 4 [Q4], October-December) time scales (Table 2) and annual time scales (Table 3) for years 2000 to 2018. Estimates at a stream segment represent the combined total upstream wastewater discharges as well as direct discharges into the stream segment. Any users of these data should review the entire metadata record and the associated manuscript (see Larger Work Citation). See 'Distribution Liability' statements for more information.

This data release presents calculated accumulated wastewater (ACCWW, as a percent of total streamflow) values for 43 National Hydrologic Dataset Version 2.1 (NHDPlus V2.1) stream segments coinciding with long-term smallmouth bass sampling locations (Table 1) in the Shenandoah River Watershed (encompassing parts of Virginia and West Virginia, USA). Values are calculated for quarter-year (Quarter 1 [Q1], January - March; Quarter 2 [Q2], April - June; Quarter 3 [Q3], July-September; Quarter 4 [Q4], October-December) time scales (Table 2) and annual time scales (Table 3) for years 2000 to 2018. Estimates at a stream segment represent the combined total upstream wastewater discharges as well as direct discharges into the stream segment. Any users of these data should review the entire metadata record and the associated manuscript (see Larger Work Citation). See 'Distribution Liability' statements for more information.

A wastewater reuse model was applied to the Upper Colorado River basin to assess the (1) percent of accumulated wastewater (ACCWW%) from municipal and industrial wastewater treatment plants (WWTPs) in each initialized (that is, has an assigned hydrosequence number for flow-routing) National Hydrography Dataset Version 2.1 (NHDPlus V2.1) stream segment; and (2) predicted environmental concentrations (PECs, in nanograms per liter) of eight per-and polyfluoroalkyl substances (PFAS) as well as the sum of the eight PFAS. Model inputs included (1) NHDPlus V2.1 stream geometry and hydrologic information (Table 1); (2) WWTP information, provided by the U.S. Environmental Protection Agency (Table 2), including average daily effluent discharges and outfall locations; and (3) measured municipal wastewater effluent PFAS concentrations (Table 4) used to calculate PECs. Outfall locations were linked to the corresponding NHDPlus V2.1 stream segment receiving the effluent prior to calculating ACCWW%. ACCWW% values were calculated for years 2007 to 2020 using mean-monthly and mean-annual NHDPlus V2.1 gage-adjusted Enhanced Runoff Method streamflow estimates. PFAS PECs were calculated for 2020 using mean-annual NHDPlus V2.1 gage-adjusted Enhanced Runoff Method streamflow estimates. PFAS PECs were calculated from accumulated wastewater from sewerage system facilities (Standard Industrial Classification code 4952, i.e. ‘municipal’) as well as potential PFAS-handling industry sectors defined by the Environmental Protection Agency (U.S. Environmental Protection Agency, 2023). Model estimates at a stream reach of interest represent the combined total upstream wastewater discharges as well as direct discharges into the segment. R (version 4.4.1) and Python (version 3.9.16) scripts were used to summarize wastewater inputs from outfall locations by COMID and route and accumulate each wastewater and predicted contaminant loads while accounting for in-stream dilution. Any users of these data should review the entire metadata record and the associated manuscript (see Larger Work Citation). See 'Distribution liability' statements for more information.

This product consists of a table of annual discharge estimates in millions of gallons per day from wastewater treatment plants (WWTPs) for 1,518 watersheds in the conterminous United States. The data are based on information extracted from the U.S. Environmental Protection Agency’s Clean Watersheds Needs Survey. The data are for 13 time periods, beginning in 1978 and ending in 2012. Total nitrogen and phosphorus loads from WWTPs per watershed for each year are also provided, based on previously published data (Falcone, 2017).