Predicting Groundwater Quality in Unmonitored Areas
Using Maps and Models to Predict Groundwater Quality
Where do contaminants occur and at what concentrations?
Groundwater provides nearly one-half of the Nation’s drinking water, and sustains the steady flow of streams and rivers and the ecological systems that depend on that flow. Unless we drill a well, how can we know the quality of the groundwater below? Learn about how the USGS is using sophisticated techniques to predict groundwater quality and view national maps of groundwater quality.
Featured: 3-D Models of As and Mn in the Glacial Aquifer System
New 3-D models from the USGS National Water Quality Program predict where high concentrations of arsenic and manganese likely occur in the glacial aquifer system, groundwater supply for 30 million. Redox conditions and pH are controlling factors.
Featured: Predicting Groundwater Age in the Glacial Aquifer System
A new 3-D model predicts groundwater age at all depths across the 25-state span of the glacial aquifer system, reports a new USGS study. About 80% of the groundwater is less than 65 years old, so it's vulnerable to anthropogenic contamination.
Although groundwater is a safe, reliable source of drinking water for millions of people nationwide, high concentrations of some chemical constituents can pose potential human-health concerns. Some of these contaminants come from the rocks and sediments of the aquifers themselves, and others are chemicals that we use in agriculture, industry, and day-to-day life. When groundwater supplies are contaminated, millions of dollars can be required for treatment so that the supplies can be usable. Contaminants in groundwater can also affect the health of our streams and valuable coastal waters. By knowing where contaminants occur in groundwater, what factors control contaminant concentrations, and what kinds of changes in groundwater quality might be expected in the future, we can ensure the availability and quality of this vital natural resource in the future.
At the USGS, researchers are using information from gathered from thousands of wells across the nation to determine how myriad factors, from groundwater age to pesticide use, affect which chemical constituents are dissolved in groundwater and at what concentrations. The constituents include trace elements, such as arsenic and manganese; radionuclides, such as radon and uranium; nutrients, such as nitrate and phosphorus; and manmade chemicals, such as the herbicide atrazine. At elevated concentrations, some of these constituents in drinking water can pose a threat to human health. Others are simply a nuisance, causing drinking water to have an unpleasant smell, taste, or appearance; cause skin or tooth discoloration; or cause corrosion or sedimentation of plumbing.
National Maps of Groundwater Quality
By combining data on the concentrations of chemical constituents measured in thousands of wells, locations of contaminant sources, and factors that affect how a constituent behaves in groundwater, scientists can use sophisticated statistical approaches to predict where a constituent is likely to occur in groundwater and at what concentration. These maps can be used by water resource managers to (1) anticipate water quality in unsampled areas or depth zones, (2) design targeted monitoring programs, (3) inform groundwater protection strategies, and (4) evaluate the sustainability of groundwater sources of drinking water.
View regional and national maps for the following chemical constituents and contaminants:
- Arsenic concentrations in the basin-fill aquifers of the Southwest
- Nitrate concentrations in shallow groundwater and deep groundwater used for drinking across the Nation
- Atrazine concentrations in shallow groundwater beneath agricultural land across the Nation
Mapping Groundwater Quality in 3-D
Just as the characteristics of an aquifer can vary greatly with depth, so can the quality of the groundwater. Domestic wells, such as those used by homeowners, typically pump groundwater from relatively shallow depths. Public-supply wells that serve many thousands of people typically pump groundwater from much greater depths—sometimes hundreds of feet or more.
Three-dimensional, or 3-D, depictions of groundwater quality are being developed for four Principal Aquifers: the Glacial Aquifer system, which extends across the northernmost one-third of the United States; the Central Valley aquifer, in California; the Mississippi Embayment aquifer in south-central U.S.; and the Northern Atlantic Coastal Plain aquifer, in the southeast. These depictions focus on groundwater quality at depths tapped by domestic-supply wells and public-supply wells. The information gained also will be used to assess the vulnerability of streams to contaminants derived from groundwater in these areas.
The web pages below are gateways to more USGS research on the Nation’s groundwater quality.
Groundwater Quality Research
Groundwater/Surface-Water Interaction
Public Supply Wells
Domestic (Private) Supply Wells
Radionuclides
Groundwater Quality in Principal Aquifers of the Nation, 1991–2010
Factors Affecting Vulnerability of Public-Supply Wells to Contamination
Groundwater Age
Volatile Organic Compounds (VOCs)
Oxidation/Reduction (Redox)
Groundwater provides nearly one-half of the Nation’s drinking water, and sustains the steady flow of streams and rivers and the ecological systems that depend on that flow. Unless we drill a well, how can we know the quality of the groundwater below? Learn about how the USGS is using sophisticated techniques to predict groundwater quality and view national maps of groundwater quality.
Featured: 3-D Models of As and Mn in the Glacial Aquifer System
New 3-D models from the USGS National Water Quality Program predict where high concentrations of arsenic and manganese likely occur in the glacial aquifer system, groundwater supply for 30 million. Redox conditions and pH are controlling factors.
Featured: Predicting Groundwater Age in the Glacial Aquifer System
A new 3-D model predicts groundwater age at all depths across the 25-state span of the glacial aquifer system, reports a new USGS study. About 80% of the groundwater is less than 65 years old, so it's vulnerable to anthropogenic contamination.
Although groundwater is a safe, reliable source of drinking water for millions of people nationwide, high concentrations of some chemical constituents can pose potential human-health concerns. Some of these contaminants come from the rocks and sediments of the aquifers themselves, and others are chemicals that we use in agriculture, industry, and day-to-day life. When groundwater supplies are contaminated, millions of dollars can be required for treatment so that the supplies can be usable. Contaminants in groundwater can also affect the health of our streams and valuable coastal waters. By knowing where contaminants occur in groundwater, what factors control contaminant concentrations, and what kinds of changes in groundwater quality might be expected in the future, we can ensure the availability and quality of this vital natural resource in the future.
At the USGS, researchers are using information from gathered from thousands of wells across the nation to determine how myriad factors, from groundwater age to pesticide use, affect which chemical constituents are dissolved in groundwater and at what concentrations. The constituents include trace elements, such as arsenic and manganese; radionuclides, such as radon and uranium; nutrients, such as nitrate and phosphorus; and manmade chemicals, such as the herbicide atrazine. At elevated concentrations, some of these constituents in drinking water can pose a threat to human health. Others are simply a nuisance, causing drinking water to have an unpleasant smell, taste, or appearance; cause skin or tooth discoloration; or cause corrosion or sedimentation of plumbing.
National Maps of Groundwater Quality
By combining data on the concentrations of chemical constituents measured in thousands of wells, locations of contaminant sources, and factors that affect how a constituent behaves in groundwater, scientists can use sophisticated statistical approaches to predict where a constituent is likely to occur in groundwater and at what concentration. These maps can be used by water resource managers to (1) anticipate water quality in unsampled areas or depth zones, (2) design targeted monitoring programs, (3) inform groundwater protection strategies, and (4) evaluate the sustainability of groundwater sources of drinking water.
View regional and national maps for the following chemical constituents and contaminants:
- Arsenic concentrations in the basin-fill aquifers of the Southwest
- Nitrate concentrations in shallow groundwater and deep groundwater used for drinking across the Nation
- Atrazine concentrations in shallow groundwater beneath agricultural land across the Nation
Mapping Groundwater Quality in 3-D
Just as the characteristics of an aquifer can vary greatly with depth, so can the quality of the groundwater. Domestic wells, such as those used by homeowners, typically pump groundwater from relatively shallow depths. Public-supply wells that serve many thousands of people typically pump groundwater from much greater depths—sometimes hundreds of feet or more.
Three-dimensional, or 3-D, depictions of groundwater quality are being developed for four Principal Aquifers: the Glacial Aquifer system, which extends across the northernmost one-third of the United States; the Central Valley aquifer, in California; the Mississippi Embayment aquifer in south-central U.S.; and the Northern Atlantic Coastal Plain aquifer, in the southeast. These depictions focus on groundwater quality at depths tapped by domestic-supply wells and public-supply wells. The information gained also will be used to assess the vulnerability of streams to contaminants derived from groundwater in these areas.
The web pages below are gateways to more USGS research on the Nation’s groundwater quality.