Water and the chemicals it contains are constantly being exchanged between the land surface and the subsurface. Surface water seeps into the ground and recharges the underlying aquifer—groundwater discharges to the surface and supplies the stream with baseflow. USGS Integrated Watershed Studies assess these exchanges and their effect on surface-water and groundwater quality and quantity.
Groundwater and surface water physically overlap at the groundwater/surface water interface through the exchange of water and chemicals. This exchange is a critical part of the hydrologic cycle. Surface water supplies recharge to the underlying aquifer, where the groundwater can remain in storage for days, months, years, centuries, or even millennia. Eventually the groundwater discharges back into the stream. Depending on how much time the water spends underground, and the geochemical conditions within the aquifer, the quality of the original recharge water can undergo profound changes before it discharges at the surface.
USGS Integrated Watershed Studies seek to better understand and quantify the exchanges at the surface water/groundwater interface. This understanding is used to forecast how the chemical quality of water will change in response to changes in climate, land use, or management practices. Integrated Watershed Studies develop methods to quantify the movement of water and chemicals between the watershed, stream, and groundwater to estimate past and forecast future water-quality conditions at regional scales. The USGS also develops new methods to interpret high-frequency water-quality monitoring data to inform and develop watershed models.
Interested in surface-water quality? Find out more here.
Interested in groundwater quality? Find out more here.
Follow the links below to web pages for associated USGS science topics.
Agriculture and the Quality of the Nation's Waters
Groundwater Quality Research
Surface-Water Quality and Ecology
Follow the links below to access data on water quality of groundwater and surface water.
Input and results from a boosted regression tree (BRT) model relating base flow nitrate concentrations in the Chesapeake Bay watershed to catchment characteristics (1970-2013)
An exploratory Bayesian network for estimating the magnitudes and uncertainties of selected water-quality parameters at streamgage 03374100 White River at Hazleton, Indiana, from partially observed data
Datasets and metadata for estimates of nitrate loads and yields from groundwater to streams in the Chesapeake Bay watershed based on land use and geology
Depth to 50 percent probability of oxic conditions, Chesapeake Bay Watershed
Hydrograph-separation results for 225 streams in the Chesapeake Bay watershed derived by using PART, HYSEP (Fixed, Local minimum, Slide), BFI, and a Recursive Digital Filter with streamflow data ranging from 1913 through 2016
Real and synthetic data used to test the Two-tracer Ratio-based Mixing Model (TRaMM)
Data on annual total nitrogen loads and watershed characteristics used to develop a method to estimate the total nitrogen loads in small streams
Water Quality and Hydrologic Data (2011-13) for Freshwater Science Paper titled, "Patterns of Diel Variation in Nitrate Concentrations in the Potomac River"
Follow these links to access USGS and IWS publications on surface-water/groundwater interaction and water quality.
Agriculture — A river runs through it — The connections between agriculture and water quality
Biofilms provide new insight into pesticide occurrence in streams and links to aquatic ecological communities
Monitoring the Riverine Pulse: Applying high-frequency nitrate data to advance integrative understanding of biogeochemical and hydrological processes
Elevated manganese concentrations in United States groundwater, role of land surface–soil–aquifer connections
An exploratory Bayesian network for estimating the magnitudes and uncertainties of selected water-quality parameters at streamgage 03374100 White River at Hazleton, Indiana, from partially observed data
UFINCH: A method for simulating unit and daily flows in networks of channels described by NHDPlus using continuous flow data at U.S. Geological Survey streamgages
Estimates of nitrate loads and yields from groundwater to streams in the Chesapeake Bay watershed based on land use and geology
Regional variability of nitrate fluxes in the unsaturated zone and groundwater, Wisconsin, USA
Estimating discharge and nonpoint source nitrate loading to streams from three end‐member pathways using high‐frequency water quality data
Predicting redox-sensitive contaminant concentrations in groundwater using random forest classification
Optimal hydrograph separation using a recursive digital filter constrained by chemical mass balance, with application to selected Chesapeake Bay watersheds
Statistically extracted fundamental watershed variables for estimating the loads of total nitrogen in small streams
Patterns of diel variation in nitrate concentrations in the Potomac River
Below are news stories associated with this project.
- Overview
Water and the chemicals it contains are constantly being exchanged between the land surface and the subsurface. Surface water seeps into the ground and recharges the underlying aquifer—groundwater discharges to the surface and supplies the stream with baseflow. USGS Integrated Watershed Studies assess these exchanges and their effect on surface-water and groundwater quality and quantity.
Groundwater and surface water physically overlap at the groundwater/surface water interface through the exchange of water and chemicals. This exchange is a critical part of the hydrologic cycle. Surface water supplies recharge to the underlying aquifer, where the groundwater can remain in storage for days, months, years, centuries, or even millennia. Eventually the groundwater discharges back into the stream. Depending on how much time the water spends underground, and the geochemical conditions within the aquifer, the quality of the original recharge water can undergo profound changes before it discharges at the surface.
USGS Integrated Watershed Studies seek to better understand and quantify the exchanges at the surface water/groundwater interface. This understanding is used to forecast how the chemical quality of water will change in response to changes in climate, land use, or management practices. Integrated Watershed Studies develop methods to quantify the movement of water and chemicals between the watershed, stream, and groundwater to estimate past and forecast future water-quality conditions at regional scales. The USGS also develops new methods to interpret high-frequency water-quality monitoring data to inform and develop watershed models.
Interested in surface-water quality? Find out more here.
Interested in groundwater quality? Find out more here.
- Science
Follow the links below to web pages for associated USGS science topics.
Agriculture and the Quality of the Nation's Waters
Intensive studies by the USGS National Water-Quality Assessment (NAWQA) Project in agricultural areas provide insight into how agricultural activities have altered the natural flow of water and the way that agricultural chemicals enter streams and aquifers, and in particular how nutrients affect algal and invertebrate communities in agricultural streams.Groundwater Quality Research
Every day, millions of gallons of groundwater are pumped to supply drinking water for about 140 million people, almost one-half of the Nation’s population. Learn about the quality and availability of groundwater for drinking, where and why groundwater quality is degraded, and where groundwater quality is changing.Surface-Water Quality and Ecology
Research by the USGS National Water Quality Assessment (NAWQA) Project on water quality of rivers and streams covers a broad range of topics, from nonpoint pollution issues to vulnerability of aquatic ecosystems. Dive in and find out more about current water-quality conditions, how and where water quality is changing, and the latest information on pesticides, nutrients, and other contaminants. - Data
Follow the links below to access data on water quality of groundwater and surface water.
Input and results from a boosted regression tree (BRT) model relating base flow nitrate concentrations in the Chesapeake Bay watershed to catchment characteristics (1970-2013)
This data release contains a boosted regression tree (BRT) model (written in the R programming language), and the input and output data from that model that were used to relate base flow nitrate concentrations in the Chesapeake Bay watershed to catchment characteristics. The input data consists of two types of information: 1) surface water nitrate concentrations collected by the USGS and partnerinAn exploratory Bayesian network for estimating the magnitudes and uncertainties of selected water-quality parameters at streamgage 03374100 White River at Hazleton, Indiana, from partially observed data
This U.S. Geological Survey (USGS) data release contains the data used in the USGS Scientific Investigations Report 2018-5053 entitled "An exploratory Bayesian network for estimating the magnitudes and uncertainties of selected water-quality parameters at streamgage 03374100 White River at Hazleton, Indiana, from partially observed data." The four datasets, which contain only ASCII characters in aDatasets and metadata for estimates of nitrate loads and yields from groundwater to streams in the Chesapeake Bay watershed based on land use and geology
This USGS data release contains datasets, metadata, and figures associated with estimating nitrate loads and yields from groundwater to streams in the Chesapeake Bay watershed based on land use and geology. There are three shapefiles with associated metadata and figures representing the shapefiles: Catchments_GWcontribN.shp: NHDPlus catchment estimates of groundwater contribution of nitraDepth to 50 percent probability of oxic conditions, Chesapeake Bay Watershed
Defining the oxic-suboxic interface is often critical for determining pathways for nitrate transport in groundwater and to streams at the local scale. Defining this interface on a regional scale is complicated by the spatial variability of reaction rates. The probability of oxic groundwater in the Chesapeake Bay watershed was predicted by relating dissolved O2 concentrations in groundwater samplesHydrograph-separation results for 225 streams in the Chesapeake Bay watershed derived by using PART, HYSEP (Fixed, Local minimum, Slide), BFI, and a Recursive Digital Filter with streamflow data ranging from 1913 through 2016
This U.S. Geological Survey (USGS) data release contains daily-mean streamflow and estimated-daily base flow for 225 stream gages in the Chesapeake Bay watershed ranging from 1913 to 2016 (beginning and end dates may vary). There is a table containing hydrograph-separation results by six methods for 225 sites (Hydrograph_separation_results_for_225_streams_in_the_Chesapeake_Bay_watershed) and a sumReal and synthetic data used to test the Two-tracer Ratio-based Mixing Model (TRaMM)
This USGS Data Release represents the synthetic and real data from hydrologically diverse streams used to test the performance and limitations of the Two-tracer Ratio-based Mixing Model (TRaMM) which uses high-frequency measures of two tracers (A and B) and streamflow to separate total streamflow into water from slowflow and fastflow sources. The ratio between the concentrations of the two tracersData on annual total nitrogen loads and watershed characteristics used to develop a method to estimate the total nitrogen loads in small streams
This USGS Data Release represents the data used to develop multiple linear regression models for estimating the loads of total nitrogen in small streams. Recursive partitioning and random forest regression were used to assess 85 geospatial, environmental, and watershed variables across 636 small (less than 585 square kilometers) watersheds to determine which variables are fundamentally important tWater Quality and Hydrologic Data (2011-13) for Freshwater Science Paper titled, "Patterns of Diel Variation in Nitrate Concentrations in the Potomac River"
This data set includes nitrate concentration, water temperature, and discharge collected every 15 minutes during Dec. 2011 - Nov. 2013 from the USGS gage at the Potomac River near Wash, DC, Little Falls Pump Sta (01646500). Additional data includes day length, and photosynthetically active radiation from USDA research station in Beltsville, MD. Several calculations derived from these data are incl - Publications
Follow these links to access USGS and IWS publications on surface-water/groundwater interaction and water quality.
Agriculture — A river runs through it — The connections between agriculture and water quality
Sustaining the quality of the Nation’s water resources and the health of our diverse ecosystems depends on the availability of sound water-resources data and information to develop effective, science-based policies. Effective management of water resources also brings more certainty and efficiency to important economic sectors. Taken together, these actions lead to immediate and longterm economic,AuthorsPaul D. Capel, Kathleen A. McCarthy, Richard H. Coupe, Katia M. Grey, Sheila E. Amenumey, Nancy T. Baker, Richard L. JohnsonFilter Total Items: 22Biofilms provide new insight into pesticide occurrence in streams and links to aquatic ecological communities
Streambed sediment is commonly analyzed to assess occurrence of hydrophobic pesticides and risks to aquatic communities. However, stream biofilms also have the potential to accumulate pesticides and may be consumed by aquatic organisms. To better characterize risks to aquatic life, the U.S. Geological Survey Regional Stream Quality Assessment measured 93 current-use and 3 legacy pesticides in bedAuthorsBarbara Mahler, Travis S. Schmidt, Lisa H. Nowell, Sharon L. Qi, Peter C. Van Metre, Michelle Hladik, Daren M. Carlisle, Mark D. Munn, Jason MayMonitoring the Riverine Pulse: Applying high-frequency nitrate data to advance integrative understanding of biogeochemical and hydrological processes
Widespread deployment of sensors that measure river nitrate (NO3-) concentrations has led to many recent publications in water resources journals including review papers focused on data quality assurance, improved load calculations, and better nutrient management. The principal objective of this paper is to review and synthesize studies of high-frequency NO3- data that have aimed to improve undersAuthorsDouglas A. Burns, Brian A. Pellerin, Matthew P. Miller, Paul Capel, Anthony J. Tesoriero, Jonathan M. DuncanElevated manganese concentrations in United States groundwater, role of land surface–soil–aquifer connections
Chemical data from 43 334 wells were used to examine the role of land surface–soil–aquifer connections in producing elevated manganese concentrations (>300 μg/L) in United States (U.S.) groundwater. Elevated concentrations of manganese and dissolved organic carbon (DOC) in groundwater are associated with shallow, anoxic water tables and soils enriched in organic carbon, suggesting soil-derived DOCAuthorsPeter B. McMahon, Kenneth Belitz, James E. Reddy, Tyler D. JohnsonAn exploratory Bayesian network for estimating the magnitudes and uncertainties of selected water-quality parameters at streamgage 03374100 White River at Hazleton, Indiana, from partially observed data
An exploratory discrete Bayesian network (BN) was developed to assess the potential of this type of model for estimating the magnitudes and uncertainties of an arbitrary subset of unmeasured water-quality parameters given the measured complement of parameters historically measured at a U.S. Geological Survey streamgage. Water-quality data for 27 water-quality parameters from 596 discrete measuremeAuthorsDavid J. HoltschlagUFINCH: A method for simulating unit and daily flows in networks of channels described by NHDPlus using continuous flow data at U.S. Geological Survey streamgages
The UFINCH (Unit Flows In Networks of Channels) computer application can be used to simulate daily and unit flows in networks of streams based on geospatial data in the National Hydrography Dataset NHDPlus (with value added attributes), and U.S. Geoogical Survey daily streamflow data from a downstream (or base) streamgage. Among streamflow augmentation methods, UFINCH has the unique capability toAuthorsDavid J. HoltschlagEstimates of nitrate loads and yields from groundwater to streams in the Chesapeake Bay watershed based on land use and geology
The water quality of the Chesapeake Bay may be adversely affected by dissolved nitrate carried in groundwater discharge to streams. To estimate the concentrations, loads, and yields of nitrate from groundwater to streams for the Chesapeake Bay watershed, a regression model was developed based on measured nitrate concentrations from 156 small streams with watersheds less than 500 square miles (mi2AuthorsSilvia Terziotti, Paul D. Capel, Anthony J. Tesoriero, Jessica A. Hopple, Scott C. KronholmRegional variability of nitrate fluxes in the unsaturated zone and groundwater, Wisconsin, USA
Process-based modeling of regional NO3− fluxes to groundwater is critical for understanding and managing water quality, but the complexity of NO3− reactive transport processes make implementation a challenge. This study introduces a regional vertical flux method (VFM) for efficient estimation of reactive transport of NO3− in the vadose zone and groundwater. The regional VFM was applied to 443 wellAuthorsChristopher T. Green, Lixia Liao, Bernard T. Nolan, Paul F. Juckem, Christopher L. Shope, Anthony J. Tesoriero, Bryant C. JurgensEstimating discharge and nonpoint source nitrate loading to streams from three end‐member pathways using high‐frequency water quality data
The myriad hydrologic and biogeochemical processes taking place in watersheds occurring across space and time are integrated and reflected in the quantity and quality of water in streams and rivers. Collection of high‐frequency water quality data with sensors in surface waters provides new opportunities to disentangle these processes and quantify sources and transport of water and solutes in the cAuthorsMatthew P. Miller, Anthony J. Tesoriero, Krista Hood, Silvia Terziotti, David M. WolockPredicting redox-sensitive contaminant concentrations in groundwater using random forest classification
Machine learning techniques were applied to a large (n > 10,000) compliance monitoring database to predict the occurrence of several redox-active constituents in groundwater across a large watershed. Specifically, random forest classification was used to determine the probabilities of detecting elevated concentrations of nitrate, iron, and arsenic in the Fox, Wolf, Peshtigo, and surrounding watersAuthorsAnthony J. Tesoriero, Jo Ann M. Gronberg, Paul F. Juckem, Matthew P. Miller, Brian P. AustinOptimal hydrograph separation using a recursive digital filter constrained by chemical mass balance, with application to selected Chesapeake Bay watersheds
Quantitative estimates of base flow are necessary to address questions concerning the vulnerability and response of the Nation’s water supply to natural and human-induced change in environmental conditions. An objective of the U.S. Geological Survey National Water-Quality Assessment Project is to determine how hydrologic systems are affected by watershed characteristics, including land use, land cAuthorsJeff P. Raffensperger, Anna C. Baker, Joel D. Blomquist, Jessica A. HoppleStatistically extracted fundamental watershed variables for estimating the loads of total nitrogen in small streams
Accurate estimation of total nitrogen loads is essential for evaluating conditions in the aquatic environment. Extrapolation of estimates beyond measured streams will greatly expand our understanding of total nitrogen loading to streams. Recursive partitioning and random forest regression were used to assess 85 geospatial, environmental, and watershed variables across 636 small (<585 km2) watersheAuthorsScott C. Kronholm, Paul D. Capel, Silvia TerziottiPatterns of diel variation in nitrate concentrations in the Potomac River
The Potomac River is a large source of N to Chesapeake Bay, where reducing nutrient loads is a focus of efforts to improve trophic status. Better understanding of NO3– loss, reflected in part by diel variation in NO3– concentrations, may refine model predictions of N loads to the Bay. We analyzed 2 y of high-frequency NO3– sensor data in the Potomac to quantify seasonal variation in the magnitudeAuthorsDouglas A. Burns, Matthew P. Miller, Brian Pellerin, Paul D. Capel - News
Below are news stories associated with this project.