Samuel A. Miller
Sam is a hydrologist in the Watershed Studies Section at the Virginia and West Virginia Water Science Center located in Richmond, VA.
Sam began working with the USGS in 2021. His research focuses on watershed-scale processes that affect downstream hydrologic response in urban and natural settings and is interested in how watershed management impacts changes in water quality and ecological health.
Education and Certifications
Ph.D. in Hydrology from the University of Wyoming
M.S. in Geology from Ohio University
B.S. in Environmental Geography & Environmental Geology from Ohio University
Science and Products
Imidacloprid in United States rivers, 2013–2022: Persistent presence and emerging chronic hazard Imidacloprid in United States rivers, 2013–2022: Persistent presence and emerging chronic hazard
Imidacloprid, a neonicotinoid insecticide, is used for agricultural and nonagricultural purposes and is toxic to nontarget organisms at low concentrations in aquatic ecosystems. A total of 12,547 water samples were collected from 2013 to 2022 from 77 rivers across the United States (U.S.) and were analyzed to evaluate detections and temporal trends in imidacloprid concentrations...
Authors
Samuel Adam Miller, Travis S. Schmidt, Larry B. Barber, Michelle L. Hladik, Dana W. Kolpin, Megan E. Shoda, Sarah M. Stackpoole
Municipal and industrial wastewater treatment plant effluent contributions to per- and polyfluoroalkyl substances in the Potomac River: A basin-scale measuring and modeling approach Municipal and industrial wastewater treatment plant effluent contributions to per- and polyfluoroalkyl substances in the Potomac River: A basin-scale measuring and modeling approach
Managing per- and polyfluoroalkyl substances (PFAS) in water resources requires a basin-scale approach. Predicted environmental concentrations (PEC) and stream-vulnerability scores for PFAS were determined for the Potomac River watershed in the eastern United States. Approximately 15% of stream reaches contained municipal and/or industrial wastewater treatment plant (WWTP) discharges...
Authors
Larry B. Barber, Samuel Adam Miller, Lee Blaney, Paul M. Bradley, Kaycee E. Faunce, Jacob Fleck, Malinda Frick, Ke He, Ryan D. Hollins, Conor J. Lewellyn, Emily H. Majcher, Mitchell A. McAdoo, Kelly L. Smalling
Factors contributing to pesticide contamination in riverine systems: The role of wastewater and landscape sources Factors contributing to pesticide contamination in riverine systems: The role of wastewater and landscape sources
Wastewater treatment plant (WWTP) discharges can be a source of organic contaminants, including pesticides, to rivers. An integrated model was developed for the Potomac River watershed (PRW) to determine the amount of accumulated wastewater percentage of streamflow (ACCWW) and calculate predicted environmental concentrations (PECs) for 14 pesticides in non-tidal National Hydrography...
Authors
Samuel Adam Miller, Kaycee E. Faunce, Larry B. Barber, Jacob Fleck, Daniel Walter Burns, Jeramy Roland Jasmann, Michelle L. Hladik
Using high-frequency monitoring data to quantify city-wide suspended-sediment load and evaluate TMDL goals Using high-frequency monitoring data to quantify city-wide suspended-sediment load and evaluate TMDL goals
Excess sediment is a common reason water bodies in the USA become listed as impaired resulting in total maximum daily loads (TMDL) that require municipalities to invest millions of dollars annually on management practices aimed at reducing suspended-sediment loads (SSLs), yet monitoring data are rarely used to quantify SSLs and track TMDL progress. A monitoring network was created to...
Authors
Samuel Adam Miller, James S. Webber, John D. Jastram, Marcus F Aguilar
Applying Multiple Tools to Inform Management of Per- and Polyfluoroalkyl Substances (PFAS) in the Potomac River Watershed
The reuse of municipal wastewater provides multiple benefits, including maintaining stream flow, recharging aquifers, and providing public water supply. However, along with the benefits are concerns related to the presence of ‘forever’ chemicals, like per- and polyfluoroalkyl substances (PFAS) in wastewater discharge. Managing PFAS in waterways is challenging because there are many potential PFAS...
Navigating PFAS Contamination: Insights from the USGS Potomac River Watershed Study
The Potomac River is a major watershed in the eastern United States that serves as a crucial water supply for millions of people. USGS researchers conducted a comprehensive investigation to identify the contributions of municipal and industrial wastewater treatment plant effluent to the levels of per-and polyfluoroalkyl substances (PFAS) in the Potomac River. This study included measuring PFAS...
New study highlights the role of wastewater and landscape sources contributing to pesticide contamination in the Potomac River watershed
Wastewater treatment plant discharges can be a source of organic contaminants, including pesticides, to rivers. Pesticide concentrations were predicted based on wastewater percentages in stream water using a modeling tool, and verified with measured concentrations to identify other potential landscape sources.
Integrated Assessments of Potential Risks to Aquatic Organisms and Public Water Supply from Wastewater-Derived Chemical Mixtures in the Chesapeake Bay Watershed
Proper management of contaminants of emerging concern in the Chesapeake Bay region requires scientific efforts to understand the risk posed to aquatic resources from the “cocktail” of multiple contaminants that is often present. This research aims to assess the occurrence, sources, environmental impacts, biological effects, and the human health impacts of toxic contaminants in rivers.
PFAS Investigations at the Virginia and West Virginia Water Science Center
Exposure to some per- and polyfluoroalkyl substances (PFAS) has been linked to harmful health effects in humans and animals. The Virginia and West Virginia Water Science Center works with local and regional partners to determine the drivers and distribution of PFAS contamination in groundwater, surface water, and drinking water supplies across Virginia and West Virginia.
Hydrologic Monitoring and Analysis to Support Water Resource Management in the City of Roanoke
The U.S. Geological Survey, partnering with the City of Roanoke and Virginia Tech, are working to monitor the water volume and quality in streams throughout the City of Roanoke. There are currently six monitoring stations within the city. Water-quality data are collected at five stations through real-time monitors. The overall objective of the study is to quantify the amount of sediment delivered...
Reconnaissance of imidacloprid in select Virginia streams, 2024–2025 Reconnaissance of imidacloprid in select Virginia streams, 2024–2025
This data release presents concentration results obtained using an enzyme-linked immunosorbent assay (ELISA) method for imidacloprid and other neonicotinoid insecticides from samples collected in 30 urban streams across Virginia between August 2024 and July 2025. ELISA analyses were conducted at the U.S. Geological Survey Strategic Laboratory Science Branch in Boulder, Colorado. The...
Imidacloprid concentrations and trends in United States Rivers, 2013-2022 Imidacloprid concentrations and trends in United States Rivers, 2013-2022
This data release presents model inputs and outputs to support an investigation of occurrence and temporal changes of imidacloprid from the U.S. Geological Survey National Water Quality Network spanning 77 sites between 2013 and 2022. Imidacloprid is a neonicotinoid insecticide used to control a wide range of agricultural and non-agricultural insect pests. The Seasonal Wave and...
Upper Colorado River Basin Accumulated Wastewater Ratios and PFAS Model Predictions (ver. 2.0, August 2025) Upper Colorado River Basin Accumulated Wastewater Ratios and PFAS Model Predictions (ver. 2.0, August 2025)
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
Data for the Potomac River Watershed Accumulated Wastewater Viewer Data for the Potomac River Watershed Accumulated Wastewater Viewer
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...
Environmental Sampling and Modeling Results to Characterize Surface-Water Quality at 32 Sites Across the Potomac River Watershed, 2022 (ver. 3.0, April 2025) Environmental Sampling and Modeling Results to Characterize Surface-Water Quality at 32 Sites Across the Potomac River Watershed, 2022 (ver. 3.0, April 2025)
This data release presents chemical results from investigations of surface-water quality in the Potomac River watershed (encompassing Washington, D.C. and parts of West Virginia, Virginia, Pennsylvania, and Maryland) conducted during low-flow conditions in July through September of 2022 and modeling results that support interpretative products. Water-quality sampling: A sampling campaign...
Environmental Sampling of Per- and Polyfluoroalkyl Substances in the Middle Chickahominy River Watershed, Virginia, 2021-2022 (ver. 2.0, September 2023) Environmental Sampling of Per- and Polyfluoroalkyl Substances in the Middle Chickahominy River Watershed, Virginia, 2021-2022 (ver. 2.0, September 2023)
These data were collected to understand the occurrence of Per- and Polyfluoroalkyl Substances (PFAS) in the middle Chickahominy River watershed. Specifically, this effort was initiated to: 1. Determine concentrations of PFAS in surface water at select locations in the middle Chickahominy River watershed; 2. Determine concentrations of PFAS in edible portions of fish at select locations...
PFAS in the Upper Colorado River Basin PFAS in the Upper Colorado River Basin
This interactive map was created to understand presumptive PFAS sources as they relate to landscape characteristics throughout the Upper Colorado River Basin.
USGS Potomac River Watershed Accumulated Wastewater Viewer USGS Potomac River Watershed Accumulated Wastewater Viewer
These data and application are provided as part of USGS research on contaminants in surface waters across the United States and supported by the USGS Water Mission Area Proxies Project and the USGS Ecosystem Mission Area Environmental Health Program (Toxic Substances Hydrology).
Interactive Map: Virginia and West Virginia PFAS Sampling Locations Interactive Map: Virginia and West Virginia PFAS Sampling Locations
This interactive map shares locations where per- and polyfluoroalkyl substances (PFAS) have been sampled by the Virginia and West Virginia Water Science Center in collaboration with partner agencies.
Science and Products
Imidacloprid in United States rivers, 2013–2022: Persistent presence and emerging chronic hazard Imidacloprid in United States rivers, 2013–2022: Persistent presence and emerging chronic hazard
Imidacloprid, a neonicotinoid insecticide, is used for agricultural and nonagricultural purposes and is toxic to nontarget organisms at low concentrations in aquatic ecosystems. A total of 12,547 water samples were collected from 2013 to 2022 from 77 rivers across the United States (U.S.) and were analyzed to evaluate detections and temporal trends in imidacloprid concentrations...
Authors
Samuel Adam Miller, Travis S. Schmidt, Larry B. Barber, Michelle L. Hladik, Dana W. Kolpin, Megan E. Shoda, Sarah M. Stackpoole
Municipal and industrial wastewater treatment plant effluent contributions to per- and polyfluoroalkyl substances in the Potomac River: A basin-scale measuring and modeling approach Municipal and industrial wastewater treatment plant effluent contributions to per- and polyfluoroalkyl substances in the Potomac River: A basin-scale measuring and modeling approach
Managing per- and polyfluoroalkyl substances (PFAS) in water resources requires a basin-scale approach. Predicted environmental concentrations (PEC) and stream-vulnerability scores for PFAS were determined for the Potomac River watershed in the eastern United States. Approximately 15% of stream reaches contained municipal and/or industrial wastewater treatment plant (WWTP) discharges...
Authors
Larry B. Barber, Samuel Adam Miller, Lee Blaney, Paul M. Bradley, Kaycee E. Faunce, Jacob Fleck, Malinda Frick, Ke He, Ryan D. Hollins, Conor J. Lewellyn, Emily H. Majcher, Mitchell A. McAdoo, Kelly L. Smalling
Factors contributing to pesticide contamination in riverine systems: The role of wastewater and landscape sources Factors contributing to pesticide contamination in riverine systems: The role of wastewater and landscape sources
Wastewater treatment plant (WWTP) discharges can be a source of organic contaminants, including pesticides, to rivers. An integrated model was developed for the Potomac River watershed (PRW) to determine the amount of accumulated wastewater percentage of streamflow (ACCWW) and calculate predicted environmental concentrations (PECs) for 14 pesticides in non-tidal National Hydrography...
Authors
Samuel Adam Miller, Kaycee E. Faunce, Larry B. Barber, Jacob Fleck, Daniel Walter Burns, Jeramy Roland Jasmann, Michelle L. Hladik
Using high-frequency monitoring data to quantify city-wide suspended-sediment load and evaluate TMDL goals Using high-frequency monitoring data to quantify city-wide suspended-sediment load and evaluate TMDL goals
Excess sediment is a common reason water bodies in the USA become listed as impaired resulting in total maximum daily loads (TMDL) that require municipalities to invest millions of dollars annually on management practices aimed at reducing suspended-sediment loads (SSLs), yet monitoring data are rarely used to quantify SSLs and track TMDL progress. A monitoring network was created to...
Authors
Samuel Adam Miller, James S. Webber, John D. Jastram, Marcus F Aguilar
Applying Multiple Tools to Inform Management of Per- and Polyfluoroalkyl Substances (PFAS) in the Potomac River Watershed
The reuse of municipal wastewater provides multiple benefits, including maintaining stream flow, recharging aquifers, and providing public water supply. However, along with the benefits are concerns related to the presence of ‘forever’ chemicals, like per- and polyfluoroalkyl substances (PFAS) in wastewater discharge. Managing PFAS in waterways is challenging because there are many potential PFAS...
Navigating PFAS Contamination: Insights from the USGS Potomac River Watershed Study
The Potomac River is a major watershed in the eastern United States that serves as a crucial water supply for millions of people. USGS researchers conducted a comprehensive investigation to identify the contributions of municipal and industrial wastewater treatment plant effluent to the levels of per-and polyfluoroalkyl substances (PFAS) in the Potomac River. This study included measuring PFAS...
New study highlights the role of wastewater and landscape sources contributing to pesticide contamination in the Potomac River watershed
Wastewater treatment plant discharges can be a source of organic contaminants, including pesticides, to rivers. Pesticide concentrations were predicted based on wastewater percentages in stream water using a modeling tool, and verified with measured concentrations to identify other potential landscape sources.
Integrated Assessments of Potential Risks to Aquatic Organisms and Public Water Supply from Wastewater-Derived Chemical Mixtures in the Chesapeake Bay Watershed
Proper management of contaminants of emerging concern in the Chesapeake Bay region requires scientific efforts to understand the risk posed to aquatic resources from the “cocktail” of multiple contaminants that is often present. This research aims to assess the occurrence, sources, environmental impacts, biological effects, and the human health impacts of toxic contaminants in rivers.
PFAS Investigations at the Virginia and West Virginia Water Science Center
Exposure to some per- and polyfluoroalkyl substances (PFAS) has been linked to harmful health effects in humans and animals. The Virginia and West Virginia Water Science Center works with local and regional partners to determine the drivers and distribution of PFAS contamination in groundwater, surface water, and drinking water supplies across Virginia and West Virginia.
Hydrologic Monitoring and Analysis to Support Water Resource Management in the City of Roanoke
The U.S. Geological Survey, partnering with the City of Roanoke and Virginia Tech, are working to monitor the water volume and quality in streams throughout the City of Roanoke. There are currently six monitoring stations within the city. Water-quality data are collected at five stations through real-time monitors. The overall objective of the study is to quantify the amount of sediment delivered...
Reconnaissance of imidacloprid in select Virginia streams, 2024–2025 Reconnaissance of imidacloprid in select Virginia streams, 2024–2025
This data release presents concentration results obtained using an enzyme-linked immunosorbent assay (ELISA) method for imidacloprid and other neonicotinoid insecticides from samples collected in 30 urban streams across Virginia between August 2024 and July 2025. ELISA analyses were conducted at the U.S. Geological Survey Strategic Laboratory Science Branch in Boulder, Colorado. The...
Imidacloprid concentrations and trends in United States Rivers, 2013-2022 Imidacloprid concentrations and trends in United States Rivers, 2013-2022
This data release presents model inputs and outputs to support an investigation of occurrence and temporal changes of imidacloprid from the U.S. Geological Survey National Water Quality Network spanning 77 sites between 2013 and 2022. Imidacloprid is a neonicotinoid insecticide used to control a wide range of agricultural and non-agricultural insect pests. The Seasonal Wave and...
Upper Colorado River Basin Accumulated Wastewater Ratios and PFAS Model Predictions (ver. 2.0, August 2025) Upper Colorado River Basin Accumulated Wastewater Ratios and PFAS Model Predictions (ver. 2.0, August 2025)
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
Data for the Potomac River Watershed Accumulated Wastewater Viewer Data for the Potomac River Watershed Accumulated Wastewater Viewer
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...
Environmental Sampling and Modeling Results to Characterize Surface-Water Quality at 32 Sites Across the Potomac River Watershed, 2022 (ver. 3.0, April 2025) Environmental Sampling and Modeling Results to Characterize Surface-Water Quality at 32 Sites Across the Potomac River Watershed, 2022 (ver. 3.0, April 2025)
This data release presents chemical results from investigations of surface-water quality in the Potomac River watershed (encompassing Washington, D.C. and parts of West Virginia, Virginia, Pennsylvania, and Maryland) conducted during low-flow conditions in July through September of 2022 and modeling results that support interpretative products. Water-quality sampling: A sampling campaign...
Environmental Sampling of Per- and Polyfluoroalkyl Substances in the Middle Chickahominy River Watershed, Virginia, 2021-2022 (ver. 2.0, September 2023) Environmental Sampling of Per- and Polyfluoroalkyl Substances in the Middle Chickahominy River Watershed, Virginia, 2021-2022 (ver. 2.0, September 2023)
These data were collected to understand the occurrence of Per- and Polyfluoroalkyl Substances (PFAS) in the middle Chickahominy River watershed. Specifically, this effort was initiated to: 1. Determine concentrations of PFAS in surface water at select locations in the middle Chickahominy River watershed; 2. Determine concentrations of PFAS in edible portions of fish at select locations...
PFAS in the Upper Colorado River Basin PFAS in the Upper Colorado River Basin
This interactive map was created to understand presumptive PFAS sources as they relate to landscape characteristics throughout the Upper Colorado River Basin.
USGS Potomac River Watershed Accumulated Wastewater Viewer USGS Potomac River Watershed Accumulated Wastewater Viewer
These data and application are provided as part of USGS research on contaminants in surface waters across the United States and supported by the USGS Water Mission Area Proxies Project and the USGS Ecosystem Mission Area Environmental Health Program (Toxic Substances Hydrology).
Interactive Map: Virginia and West Virginia PFAS Sampling Locations Interactive Map: Virginia and West Virginia PFAS Sampling Locations
This interactive map shares locations where per- and polyfluoroalkyl substances (PFAS) have been sampled by the Virginia and West Virginia Water Science Center in collaboration with partner agencies.