Water-Quality Trends
Changes in Water Quality of U.S. Rivers
Human activities have markedly changed the water quality of rivers in the past few decades according to a new study by the U.S. Geological Survey—concentrations of some water-quality constituents have increased while others have decreased.
Learn MoreSuspended Sediment in Streams Decreasing
Concentrations of suspended sediment in many streams are decreasing, reports a new study by the USGS National Water Quality Program. Changes in land management are largely responsible.
Learn MoreScience Center Objects
Is water quality getting better or worse? Answering this deceptively simple question has been a fundamental objective of the USGS National Water-Quality Assessment Project’s research. Learn about trends in contaminants in the nation’s streams and rivers, trends in contaminants that collect in the bed sediment of streams and lakes, and changes in the quality of the nation’s groundwater.
In 1991, Congress established the National Water-Quality Assessment (NAWQA) Project to address where, when, why, and how the Nation's water quality has changed, or is likely to change in the future, in response to human activities and natural factors. In response, the NAWQA Project developed multi-pronged approaches to characterize trends in diverse contaminants in the Nation’s streams, rivers, bed sediment, and groundwater.
Trends in Contaminant Concentrations and Loads in the Nation’s Streams and Rivers
The NAWQA Project, other USGS programs, and other Federal, State, and local agencies have collected years of water-quality data to support their assessments of changing water-quality conditions. For the first time, all of these data have been combined to support the most comprehensive assessment conducted to date of water-quality trends in the United States. Collectively, these data provide insight into how natural features and human activities have contributed to water-quality changes over time in Nation's streams and rivers. Data are updated annually. The online Water-Quality Trends mapping tool allows users to visualize trends in water chemistry (nutrients, pesticides, sediment, carbon, and salinity) and aquatic ecology (fish, invertebrates, and algae)
Tributaries contribute to water quality in the Arkansas River, one of hundreds of U.S. streams and rivers where water-quality trends are being monitored. (Credit: Stan Paxton)
Trends in Sediment-Associated Contaminants
Many contaminants adhere, or sorb, to sediment, so that standard water-quality sampling and analysis is often unable to detect changes in their concentrations over time. Sediment-associated contaminants include legacy contaminants, such as DDT and PCBs, and contaminants currently released into the environment, such as the pesticide bifenthrin and polycyclic aromatic hydrocarbons (PAHs). An alternative approach to determine trends in concentrations of these contaminants is the use of sediment cores collected from lakes and reservoirs.
Changes in Groundwater Quality
Monitoring groundwater quality at a public-supply well.
USGS scientists are characterizing groundwater quality in principal aquifers, the primary source of the Nation's groundwater used for drinking. Users can access an online tool to see how concentrations of pesticides, nutrients, metals, and organic contaminants in groundwater are changing during decadal periods across the Nation, and see in real time how chemical properties of groundwater at some sites are fluctuating.
National Water-Quality Assessment (NAWQA)
Our surface water, groundwater, and aquatic ecosystems are priceless resources, used by people across the Nation for drinking, irrigation, industry, and recreation. The National Water-Quality Assessment (NAWQA) Project is a leading source of scientific data and knowledge for development of science-based policies and management strategies to improve and protect our water resources.
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Date published: March 2, 2019Status: ActiveWater Quality in the Nation’s Streams and Rivers – Current Conditions and Long-Term Trends
The Nation's rivers and streams are a priceless resource, but pollution from urban and agricultural areas pose a threat to our water quality. To understand the value of water quality, and to more effectively manage and protect the Nation's water resources, it's critical that we know the current status of water-quality conditions, and how and why those conditions have been changing over time....
Contacts: Lori SpragueAttribution: Water Resources -
Date published: February 28, 2019Status: ActiveGroundwater Quality—Current Conditions and Changes Through Time
Is groundwater the source of your drinking water? The USGS is assessing the quality of groundwater used for public supply using newly collected data along with existing water-quality data. Learn more about this invisible, vital resource so many of us depend on.
Contacts: Bruce LindseyAttribution: Water Resources, National Water Quality Program -
Date published: February 27, 2019Status: ActiveWater-Quality Trends From Lake Cores
Sediment cores let us look back in time at the contaminant history of a watershed. Learn about what lake and reservoir sediment cores tell us about trends in metals, organochlorine pesticides, polycyclic aromatic hydrocarbons, and other sediment-related contaminants.
Contacts: Peter C Van MetreAttribution: Water Resources
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Year Published: 2019Water-quality trends in US rivers: Exploring effects from streamflow trends and changes in watershed management
We present a conceptual model that explores the relationship of streamflow trends to 15 water-quality parameters at 370 sites across the contiguous United States (US). Our analytical framework uses discrete water-quality data, daily streamflow records, and a statistical model to estimate water-quality trends between...
Murphy, Jennifer C.; Sprague, Lori A.
Landscape drivers of dynamic change in water quality of US rivers
Water security is a top concern for social well-being and dramatic changes in the availability of freshwater have occurred as a result of human uses and landscape management. Elevated nutrient loading and perturbations to major ion composition have resulted from human activities and have degraded freshwater resources. This study addresses the...
Stets, Edward G.; Sprague, Lori A.; Oelsner, Gretchen P.; Johnson, Henry M.; Murphy, Jennifer C.; Ryberg, Karen R.; Vecchia, Aldo V.; Zuellig, Robert E.; Falcone, James A.; Riskin, Melissa L. Changing suspended sediment in United States rivers and streams: Linking sediment trends to changes in land use/cover, hydrology and climate
Sediment is one of the leading pollutants in rivers and streams across the United States (US) and the world. Between 1992 and 2012, concentrations of annual mean suspended sediment decreased at over half of the 137 stream sites assessed across the contiguous US. Increases occurred at less than 25 % of the sites, and the direction of change was...
Murphy, Jennifer C. Causal factors for pesticide trends in streams of the United States: Atrazine and deethylatrazine
Pesticides are important for agriculture in the United States, and atrazine is one of the most widely used and widely detected pesticides in surface water. A better understanding of the mechanisms by which atrazine and its degradation product, deethylatrazine, increase and decrease in surface waters can help inform future decisions for water-...
Ryberg, Karen R.; Stone, Wesley W.; Baker, Nancy T. Historical changes in fish communities in urban streams of the southeastern U.S. and the relative importance of water-quality stressors
A total of 71 stream sites representing a gradient of urban land use was sampled across the Piedmont of the southeastern U.S. in 2014. Fish data collected (observed) at each site were compared to an expected community based on georeferenced historical (~1950 - ~1990) species occurrence records for stream segments (1:100,000 scale) containing the...
Meador, Michael Network controls on mean and variance of nitrate loads from the Mississippi River to the Gulf of Mexico
Excessive nitrate loading to the Gulf of Mexico (GoM) has caused widespread hypoxia over many decades. Despite recent reductions in nitrate loads observed at local scales, decreases in nitrate loading from the MRB to the GoM have been small (1.58 % during 2002-2012) with a low level of analytical confidence in this trend. This work seeks to...
Crawford, John T.; Stets, Edward G.; Sprague, Lori A. Projected urban growth in the Southeastern USA puts small streams at risk
Future land-use development has the potential to profoundly affect the health of aquatic ecosystems in the coming decades. We developed regression models predicting the loss of sensitive fish (R2=0.39) and macroinvertebrate (R2=0.64) taxa as a function of urban and agricultural land uses and applied them to projected urbanization of the rapidly...
Van Metre, Peter C.; Waite, Ian R.; Qi, Sharon L.; Mahler, Barbara; Terando, Adam; Wieczorek, Michael; Meador, Michael R.; Bradley, Paul M.; Journey, Celeste A.; Schmidt, Travis S.; Carlisle, Daren Variable impacts of contemporary versus legacy agricultural phosphorus on US river water quality
Phosphorus (P) fertilizer has contributed to the eutrophication of freshwater ecosystems. Watershed-based conservation programs aiming to reduce external P loading to surface waters have not resulted in significant water-quality improvements. One factor that can help explain the lack of water-quality response is remobilization of accumulated...
Stackpoole, Sarah M.; Stets, Edward G.; Sprague, Lori A. Regional patterns of anthropogenic influences on streams and rivers in the conterminous United States, from the early 1970s to 2012
This paper introduces a dataset containing consistent time-series measurements of anthropogenic activities potentially affecting stream quality across the conterminous United States and summarizes the most noteworthy trends from 61 variables in 16 categories. Data include measures of atmospheric deposition, agricultural production, livestock,...
Falcone, James A.; Murphy, Jennifer C.; Sprague, Lori A. Assessing water-quality changes in U.S. rivers at multiple geographic scales using results from probabilistic and targeted monitoring
Two commonly used approaches for water quality monitoring are probabilistic and targeted. In a probabilistic approach like the US Environmental Protection Agency’s National Rivers and Streams Assessment, monitoring sites are selected using a statistically representative approach. In a targeted approach like that used by many monitoring...
Sprague, Lori A.; Mitchell, Richard M; Pollard, Amina I.; Falcone, James A. Recent trends in nutrient and sediment loading to coastal areas of the conterminous U.S.: Insights and global context
Coastal areas in the U.S. and worldwide have experienced massive population and land use changes contributing to significant degradation of coastal ecosystems. Excess nutrient pollution causes coastal ecosystem degradation, and both regulatory and management efforts have targeted reducing nutrient and sediment loading to coastal rivers. Decadal...
Oelsner, Gretchen P.; Stets, Edward G. Effects of antecedent streamflow and sample timing on trend assessments of fish, invertebrate, and diatom communities
Detecting trends in biological attributes is central to many stream monitoring programs; however, understanding how natural variability in environmental factors affects trend results is not well understood. We evaluated the influence of antecedent streamflow and sample timing (covariates) on trend estimates for fish, invertebrate, and diatom taxa...
Zuellig, Robert E.; Carlisle, Daren Water-quality trends in US rivers: Exploring effects from streamflow trends and changes in watershed management
We present a conceptual model that explores the relationship of streamflow trends to 15 water-quality parameters at 370 sites across the contiguous United States (US). Our analytical framework uses discrete water-quality data, daily streamflow records, and a statistical model to estimate water-quality trends between...
Murphy, Jennifer C.; Sprague, Lori A.
Changes in anthropogenic influences on streams and rivers in the conterminous U.S. over the last 40 years, derived for 16 data themes
This product consists of time-series calculations of anthropogenic characteristics derived for 16 data themes for multiple scales covering the conterminous United States. The characteristics are those which (a) have consistent data sources, and (b) have the potential to affect the water quality of streams and rivers. All 16 data themes are provided for Hydrologic Unit Code level-10 %
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Date published: March 4, 2019Water-Quality Changes in the Nation's Streams and Rivers
This mapper provides results from the largest-ever assessment of water quality changes in the Nation's streams and rivers. More than 185 million water-quality records from over 600 Federal, State, Tribal, and local organizations were screened as part of this assessment.
Attribution: Water Resources, Upper Midwest Water Science Center -
Date published: January 1, 2018
Data from Decadal Change in Groundwater Quality Web Site, 1988-2014, Version 2.0
Evaluating Decadal Changes in Groundwater Quality: Groundwater quality data were collected from 5,000 wells between 1988-2001 (first sampling event) by the U.S. Geological Survey’s National Water-Quality Assessment Project. Samples are collected in groups of 20-30 wells with similar characteristics called networks. About 1,500 of these wells in 67 networks were sampled about 10
Attribution: Water Resources, National Water Quality Program -
Date published: January 1, 2018
Changes in anthropogenic influences on streams and rivers in the conterminous U.S. over the last 40 years, derived for 16 data themes
This product consists of time-series calculations of anthropogenic characteristics derived for 16 data themes for multiple scales covering the conterminous United States. The characteristics are those which (a) have consistent data sources, and (b) have the potential to affect the water quality of streams and rivers. All 16 data themes are provided for Hydrologic Unit Code level-10 %
Attribution: Water Resources, National Water Quality Program -
Date published: January 1, 2018
Water-quality trends and trend component estimates for the Nation's rivers and streams using Weighted Regressions on Time, Discharge, and Season (WRTDS) models and generalized flow normalization, 1972-2012
Nonstationary streamflow due to environmental and human-induced causes can affect water quality over time, yet these effects are poorly accounted for in water-quality trend models. This data release provides instream water-quality trends and estimates of two components of change, for sites across the Nation previously presented in Oelsner et al. (2017). We used previously calibrated Weigh
Attribution: Lower Mississippi-Gulf Water Science Center -
Date published: January 1, 2017
Pesticide concentration and streamflow datasets used to evaluate pesticide trends in the Nation’s rivers and streams, 1992-2012 (input)
In 1991, the U.S. Geological Survey (USGS) began a study of more than 50 major river basins across the Nation as part of the National Water-Quality Assessment (NAWQA) project of the National Water-Quality Program. One of the major goals of the NAWQA project is to determine how water-quality conditions change over time. To support that goal, long-term consistent and comparable monitor
Attribution: Water Resources -
Date published: January 1, 2017
Pesticide concentration and streamflow datasets used to evaluate pesticide trends in the Nation’s rivers and streams, 1992-2012 (output)
In 1991, the U.S. Geological Survey (USGS) began a study of more than 50 major river basins across the Nation as part of the National Water-Quality Assessment (NAWQA) project of the National Water-Quality Program. One of the major goals of the NAWQA project is to determine how water-quality conditions change over time. To support that goal, long-term consistent and comparable monitor
Attribution: Water Resources -
Date published: January 1, 2017
Watershed characteristics for study sites of the Surface Water Trends project, National Water Quality Program
This product consists of 29 datasets of tabular data and associated metadata for watershed characteristics of 1,530 study sites of the Surface Water Trends (SWT) project of the U.S. Geological Survey’s (USGS) National Water Quality Program (NWQP). The project is conducting national studies of trends in water quality of streams and rivers for periods ranging from 10 to 40 ye
Attribution: National Water Quality Program -
Date published: April 6, 2016
Classification of Chloride-to-Sulfate Mass Ratio for U.S. Groundwater With Respect to the Potential to Promote Galvanic Corrosion of Lead, 1991-2015; Water Well Data and Characteristic Values for States
Galvanic corrosion of lead in water distribution systems can occur when lead pipe or lead solder is in contact with a dissimilar metal such as copper. If the source water entering those systems has a relatively elevated chloride-to-sulfate mass ratio (CSMR), the potential for galvanic corrosion to occur is elevated (Gregory 1985; Edwards and Triantafyllidou, 2007), especially in w
Attribution: California Water Science Center
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Date published: January 22, 2020Nitrate loads entering the Gulf of Mexico have not changed despite reductions at local scales
Reducing delivery of nitrate to the Gulf of Mexico is critical to decreasing the size of the “dead zone”—an area of hypoxia, or low dissolved oxygen—in Louisiana coastal waters. A new USGS study reports that larger, more widespread decreases in nitrate loading to the Gulf are needed to achieve the target levels of a 25% reduction by...
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Date published: May 6, 2019Sampling design brings insights to changing stream quality
How does the choice of sampling approach affect our perception of whether water quality in streams and rivers has changed over time? A new joint U.S....
Attribution: Water Resources, National Water Quality Program -
Date published: June 2, 2016USGS Online Mapper Provides a Decadal Look at Groundwater Quality
A first of its kind, national assessment of an unseen, valuable resource used by millions of people.
Attribution: Water Resources, National Water Quality Program -
Date published: October 28, 2015U.S. Rivers Show Few Signs of Improvement from Historic Nitrate Increases
During 1945 to 1980, nitrate levels in large U.S. rivers increased up to fivefold in intensively managed agricultural areas of the Midwest, according to a new U.S. Geological Survey study. In recent decades, nitrate changes have been smaller and levels have remained high in most of the rivers studied.
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Date published: August 26, 2015Trends in River Pesticide Levels Echo Pesticide Use
Trends in pesticide concentrations in 38 major rivers in the U.S. during 1992-2010 reflect large-scale trends in pesticide use and regulatory changes, according to a new study by the U.S. Geological Survey.
Attribution: National Water Quality Program -
Date published: July 8, 2014
USGS Release: Large Rivers in U.S. are Becoming Less Acidic
Several large rivers in the U.S. are less acidic now, due to decreasing acidic inputs, such as industrial waste, acid mine drainage, and atmospheric deposition.
Attribution: Water Resources, Toxic Substances Hydrology