How does the water quality measure up? It all depends on what the water will be used for and what contaminants are of interest. Water-quality benchmarks are designed to protect drinking water, recreation, aquatic life, and wildlife. Here you’ll find links to some of the most widely used sets of water, sediment, and fish tissue benchmarks and general guidance about their interpretation.
Featured: Updated Information on Groundwater Quality & Benchmarks
New USGS fact sheets update information on groundwater quality in the nation's most heavily used aquifers. Overall, inorganic constituents related to the interaction of groundwater and aquifer rocks most commonly exceed human-health benchmarks.
A water-quality benchmark is defined here as a threshold value against which measured concentrations can be compared to help assess the potential effects of contaminants on water quality. Benchmarks typically apply to a specific contaminant(s) in a specific sampling medium for a specific beneficial use:
-
Contaminant: contaminant classes for which benchmarks are available include pesticides, volatile organic compounds (VOC), pharmaceuticals, polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB), metals, and nutrients;
-
Sampling medium: drinking water, ambient surface water, bed sediment, whole fish, or edible fish tissue; and
-
Beneficial use: the use that the benchmark is designed to protect, for example, drinking water, recreation, aquatic life, or wildlife.
“Benchmark” is a generic term, and can include any of the following:
-
Standard or regulation: threshold values that are legally enforceable by agencies of the U.S. Government or Canada. Within the U.S., the National Primary Drinking Water Regulations (NPDWR) include standards and treatment techniques that apply to public water systems as part of the Safe Drinking Water Act (SDWA).
-
Guideline: threshold values that have no regulatory status but are issued in an advisory capacity.
-
Criteria: within the U.S., criteria are part of the definition of a water-quality standard in Sec 303(c) of the Clean Water Act (CWA). Also, 304(a) criteria are published values that reflect scientific knowledge on the effects of priority pollutants on health and welfare, including effects on aquatic life, plants, wildlife, shorelines, beaches, esthetics and recreation; the concentration and dispersal of pollutants or their byproducts; and the effects on biological community diversity, productivity, and stability (Section 304(a) of CWA).
This web page focuses on national-scale benchmarks established for freshwater systems in the United States or Canada. However, a few types of benchmarks from the States or the general scientific literature also are included, for particular sampling media and beneficial uses that have few or no national guidelines. Examples of these include whole-fish benchmarks for protection of wildlife, or human health benchmarks for pharmaceuticals.
Use of Benchmarks in Interpreting Water-Quality Data
Contaminant benchmarks can be used in screening-level assessments, in which site-specific estimates of contaminant exposure (concentrations or concentration statistics) determined from measurements of contaminants in various sampling media are compared to water-quality benchmarks. This approach has been used for many years by the USGS National Water Quality Program (such as in USGS Circular 1291, Pesticides in the Nation’s Stream and Ground Water 1992-2001), and it is similar in concept to U.S. Environmental Protection Agency (USEPA) screening-level assessments for pesticides, which USEPA uses in early stages of ecological risk assessments to evaluate the potential impact of pesticides to non-target organisms. Screening-level assessments are not a substitute for either risk assessments, which include many more factors (such as additional avenues of exposure), or site-specific studies of effects. Rather, comparisons of measured or estimated concentrations with water-quality benchmarks provide an initial perspective on the potential for adverse effects, as well as a framework for prioritizing additional investigations that may be warranted. Concentrations that exceed a benchmark do not necessarily indicate that adverse effects are occurring—they indicate that adverse effects might occur and that sites where benchmarks are exceeded may warrant further investigation. (See Characteristics and Limitations of Screening-Level Assessments section.) In general, effective use of benchmarks in water-quality assessment requires an understanding of how the benchmarks were derived and information about the specific hydrologic system being studied. Users are encouraged to consult the online sources for background information on the technical basis for the benchmarks being used, and any underlying assumptions, to better interpret what it means if a measured concentration exceeds a benchmark.
Benchmark Types and Sources
Click on the links below or scroll down the page to see specific benchmarks listed, with links to more information.
I. WATER COLUMN
A. DRINKING WATER
1. USEPA Drinking Water Regulations and Health Advisories
2. USEPA Human Health Benchmarks for Pesticides
3. USGS Health-Based Screening Levels
4. USEPA Regional Screening Levels for Chemical Contaminants at Superfund Sites
5. Canadian Guidelines for Drinking Water Quality
6. Minnesota Department of Health Pharmaceutical Water Screening Values
B. AMBIENT SURFACE WATER
1. USEPA Ambient Water-Quality Criteria for the Protection of Human Health
2. USEPA Recreational Water-Quality Criteria
3. USEPA Ambient Water-Quality Criteria for the Protection of Aquatic Organisms
4. USEPA (Office of Pesticide Programs) Aquatic Life Benchmarks
5. Canadian Water Quality Guidelines for the Protection of Aquatic Life
6. State numeric water quality criteria for Nitrogen and Phosphorus
7. Aquatic life water quality criteria for selected pesticides
8. Pesticide Toxicity Index (2014 update): an additive model for pesticide mixtures
II. BED SEDIMENT
A. WHOLE BED SEDIMENT
1. USEPA Equilibrium Partitioning Sediment Benchmarks
2. Canadian Interim Sediment Quality Guidelines
3. Consensus-Based Sediment Quality Guidelines
4. Chronic Toxicity Thresholds for Fipronil and Pyrethroid Pesticides in Sediment
5. Freshwater Sediment Benchmarks for Currently Used Pesticides
III. FISH AND SHELLFISH TISSUE
A. EDIBLE FISH AND SHELLFISH TISSUE
1. USEPA Tolerances
2. FDA Action Levels
3. USEPA Recommended Screening Values
4. USEPA database of U.S. State, Territory, and Tribal fish consumption advisories
B. WHOLE FISH
1. Canadian Tissue Residue Guidelines for the Protection of Wildlife Consumers of Aquatic Biota
2. New York Fish Flesh Criteria for Piscivorous Wildlife
3. Pesticide Whole-Fish Benchmark Ranges for Protection of Fish-Eating Wildlife, Compiled by the
USGS National Water-Quality Assessment Program
Characteristics and Limitations of Screening-Level Assessments
Screening-level assessments are a first step toward addressing the question of whether contaminants are present at concentrations that may affect human health, aquatic life or wildlife. They provide a perspective on where effects are most likely to occur and what contaminants may be responsible. Screening-level assessments are primarily intended to identify and prioritize needs for further investigation and have the following characteristics and limitations:
- The benchmarks used in a screening-level assessment are selected to correspond to both the sampling medium (drinking water, ambient surface water, bed sediment, whole fish, or edible fish tissue) and the beneficial uses of the hydrologic system being studied (human health, aquatic life, or wildlife). More than one type of benchmark may be appropriate for some samples and some hydrologic systems (such as surface water from a stream that is used for drinking water and that also supports aquatic life).
- Many water-quality benchmarks selected for the screening-level assessment are estimates of no-effect levels, such that concentrations below the benchmarks are expected to have a low likelihood of adverse effects and concentrations above a benchmark have a greater likelihood of adverse effects, which generally increases with concentration. One exception is for sediment benchmarks, which sometimes come in pairs for a given contaminant; if so, typically the lower value defines concentrations below which adverse effects are not expected and the upper value defines concentrations above which adverse effects are likely.
- The presence of contaminants in environmental samples at concentrations that exceed benchmarks does not indicate that adverse effects are certain to occur. Conversely, concentrations that are below benchmarks do not guarantee that adverse effects will not occur but indicate that they are expected to be negligible—subject to the limitations of both benchmarks (e.g., underlying assumptions) and concentration measurements (e.g., analytical detection limits), and the assumption that effects of the contaminant are not unduly affected by environmental conditions or the presence of co-occurring contaminants.
- The potential for adverse effects of contaminants on humans, aquatic life, and fish-eating wildlife can only be partially addressed because monitoring studies typically analyze for a small fraction of all the contaminants that may be present in the environment. In addition, some contaminants do not have benchmarks available.
- Most water-quality benchmarks are based on toxicity tests of individual chemicals, whereas contaminants usually occur as mixtures. Comparisons to single-compound benchmarks may tend to underestimate the potential for adverse effects.
- Water-quality benchmarks for different contaminants and media are not always comparable because they have been derived by a number of different approaches, using a variety of types of toxicity values and test species.
- For some benchmarks, there is substantial uncertainty in underlying estimates of no-effect levels, depending on the methods used to derive them and the quantity and types of toxicity information on which they are based.
- Estimates of contaminant exposure derived from either measured or estimated concentrations are also uncertain—particularly for short-term exposure of aquatic organisms to pesticides in lotic systems (rivers and streams), which tends to be underestimated by periodic discrete sampling procedures.
Benchmark Types and Sources:
1. USEPA Drinking Water Regulations and Health Advisories
Contaminant Types: Microorganisms, disinfectants, disinfection byproducts, inorganic chemicals, organic chemicals, radionuclides
Sampling Medium: Drinking water
Resource Protected: Human health
Sources: National Primary Drinking Water Regulations (List of Contaminants and their MCLs), Drinking Water Standards and Advisory Tables (List of Contaminants and their MCLs, Health Advisories (HAs) and Cancer Risk Concentrations) (March 2018)
2. USEPA Human Health Benchmarks for Pesticides
Contaminant Types: Pesticides
Sampling Medium: Drinking water
Resource Protected: Human health
Sources: Human Health Benchmarks for Pesticides (available for food-use pesticides without drinking water regulations or health advisories) (2017), Supporting document: Human Health Benchmarks for Pesticides: Updated 2017 Technical Document (January 2017)
3. USGS Health-Based Screening Levels
Contaminant Types: Pesticides, hormones, pharmaceuticals, other emerging contaminants, volatile organic compounds (VOCs), semivolatile organic compounds (SVOCs), organochlorine compounds, trace elements, major ions, nutrients, radionuclides
Sampling Medium: Drinking water
Resource Protected: Human health
Sources: Health-Based Screening Levels for Evaluating Water-Quality Data (May 2018), Supporting document: Development and Application of Health-Based Screening Levels for Use in Water-Quality Assessments (2007), Updated 2018 Technical Information (May 2018)
4. USEPA Regional Screening Levels for Chemical Contaminants at Superfund Sites
Contaminant Types: Pesticides, PAHs, PCBs, other organic chemicals, inorganic chemicals
Sampling Medium: Drinking water (also available for soil and air)
Resource Protected: Human health
Sources: Regional Screening Levels (RSLs) (May 2018), RSLs Tables (May 2018), RSLs User Guide
5. Canadian Guidelines for Drinking Water Quality
Contaminant Types: Microorganisms, pesticides, other organic chemicals, inorganic chemicals, physical parameters, radionuclides
Sampling Medium: Drinking water
Resource Protected: Human health
Sources: Canadian Drinking Water Guidelines (August 2018), Guidelines for Canadian Drinking Water Quality, Summary Table (February 2017)
6. Minnesota Department of Health Pharmaceutical Water Screening Values
Contaminant Types: Pharmaceuticals
Sampling Medium: Drinking water
Resource Protected: Human health
Sources: Rapid Assessments for Pharmaceuticals Project, Pharmaceutical Water Screening Values Report, Download the table of screening values: Pharmaceutical Water Screening Table (July 2018)
1. USEPA Ambient Water-Quality Criteria for the Protection of Human Health
Contaminant Types: USEPA priority pollutants (organic and inorganic chemicals)
Sampling Medium: Ambient surface water
Resource Protected: Human health
Sources: National Recommended Water Quality Criteria
2. USEPA Recreational Water-Quality Criteria
Contaminant Types: Microorganisms/pathogens
Sampling Medium: Ambient surface water
Resource Protected: Human health/ recreation
Sources: 2012 Recreational Water Quality Criteria; Recreational Water Quality Criteria document, Office of Water 820-F-12-058 (2012); Draft Human Health Recreational Ambient Water Quality Criteria and/or Swimming Advisories for Microcystins and Cylindrospermopsin (2016)
3. USEPA Ambient Water-Quality Criteria for the Protection of Aquatic Organisms
Contaminant Types: USEPA priority pollutants (organic and inorganic chemicals)
Sampling Medium: Ambient surface water
Resource Protected: Aquatic life
Sources: National Recommended Water Quality Criteria
4. USEPA (Office of Pesticide Programs) Aquatic Life Benchmarks
Contaminant Types: Pesticides, pesticide degradates
Sampling Medium: Ambient surface water
Resource Protected: Aquatic life
Sources: Office of Pesticide Programs' Aquatic Life Benchmarks (October 2018)
5. Canadian Water Quality Guidelines for the Protection of Aquatic Life
Contaminant Types: Pesticides, PAHs, VOCs, other organic chemicals, metals, other inorganic chemicals
Sampling Medium: Ambient surface water
Resource Protected: Aquatic life
Sources: Canadian Environmental Quality Guidelines; Canadian Environmental Quality Guidelines, Summary Table (online searchable database and access to downloadable Excel file)
6. State numeric water quality criteria for Nitrogen and Phosphorus
Contaminant Types: Nutrients
Sampling Medium: Ambient surface water
Resource Protected: Multiple, including aquatic life, public health, navigation (impacts from eutrophication)
Sources: Numeric Nutrient Water Quality Criteria; State Progress Toward Developing Numeric Nutrient Water Quality Criteria for Nitrogen and Phosphorus (May 2018)
7. Aquatic life water quality criteria for selected pesticides (derived via the UC Davis method) (2012)
Contaminant Types: Organophosphate insecticides, pyrethroid insecticides, diuron
Sampling Medium: Ambient surface water
Resource Protected: Aquatic life
Sources: Aquatic Life Water Quality Criteria for Selected Pesticides: Tjeerdema, R.S., ed., 2012, Reviews of Environmental Contamination and Toxicology
8. Pesticide Toxicity Index (2014 update): an additive model for pesticide mixtures
Contaminant Types: Pesticides
Sampling Medium: Ambient surface water
Resource Protected: Aquatic life
Sources: Pesticide Toxicity Index: A Tool for Assessing Potential Toxicity of Pesticide Mixtures to Freshwater Aquatic Organisms, Nowell, L.H., et al., 2014, Science of the Total Environment, v. 476-477, p. 144-157.
1. USEPA Equilibrium Partitioning Sediment Benchmarks
Contaminant Types: Organochlorine pesticides, PAHs, other nonionic organic chemicals, metals
Sampling Medium: Bed sediment
Resource Protected: Benthic organisms
Sources: Equilibrium Partitioning Sediment Benchmarks (ESBs) for the Protection of Benthic Organisms: Procedures for the Determination of the Freely Dissolved Interstitial Water Concentrations of Nonionic Organics (2012): EPA/600/R-02/012:
Procedures for the Derivation of Equilibrium Partitioning Sediment Benchmarks (ESBs) for the Protection of Benthic Organisms:
Compendium of Tier 2 Values for Nonionic Organics. See Table C-1. (March 2008) EPA/600/R-02/016
Dieldrin (2003) EPA/600/R-02/0010,
Endrin (2003) EPA/600/R-02/009,
PAH Mixtures (November 2003) EPA/600/R-02/013,
Metal Mixtures (Cadmium, Copper, Lead, Nickel, Silver, and Zinc) (2005) EPA/600/R-02/011
2. Canadian Interim Sediment Quality Guidelines
Contaminant Types: Organochlorine pesticides, PAHs, PCBs, metals
Sampling Medium: Bed sediment
Resource Protected: Aquatic Life
Sources: Canadian Environmental Quality Guidelines (includes introductory text, fact sheets for individual contaminants, and the 1999 protocol for derivation of Canadian sediment-quality guidelines for the protection of aquatic life); Canadian Environmental Quality Guidelines, Summary Table (online searchable database and access to downloadable Excel file)
3. Consensus-Based Sediment Quality Guidelines
Contaminant Types: Organochlorine pesticides, PAHs, PCBs, metals
Sampling Medium: Bed sediment
Resource Protected: Aquatic Life
Sources: Development and Evaluation of Consensus-Based Sediment Quality Guidelines for Freshwater Ecosystems. MacDonald, D.D. et al., 2000, Archives of Environmental Contamination and Toxicology, v. 39, p. 20-31; Prediction of Sediment Toxicity Using Consensus-Based Freshwater Sediment Quality Guidelines, Ingersoll, C.G. et al., 2001, Archives of Environmental Contamination and Toxicology, v. 41, p. 8-21.
4. Chronic Toxicity Thresholds for Fipronil and Pyrethroid Pesticides in Sediment
Contaminant Types: Fipronil and pyrethroid insecticides
Sampling Medium: Bed sediment
Resource Protected: Aquatic Life
Sources: Contaminants in Stream Sediments from Seven U.S. Metropolitan Areas: Data Summary of a National Pilot Study, Moran, P.W., et al., 2012, USGS SIR 2011-5092. See Table 13 for pesticide benchmark values and p. 19 of the text for the derivation. Available for pyrethroid and fipronil compounds
5. Freshwater Sediment Benchmarks for Currently Used Pesticides
Contaminant Types: Pesticides
Sampling Medium: Bed sediment
Resource Protected: Aquatic Life
Sources: Development and application of freshwater sediment-toxicity benchmarks for currently used pesticides, Nowell, L.H., et al., 2016, Science of the Total Environment, v. 550, p. 835-850.
III. FISH AND SHELLFISH TISSUE
A. EDIBLE FISH AND SHELLFISH TISSUE
Contaminant Types: Pesticides
Sampling Medium: Edible fish and shellfish
Resource Protected: Human health
Sources: Regulation of pesticide residues on Food (Information about EPA tolerances); Code of Federal Regulations, go to current year, Title 40, Chapter I, Part 180, Subpart C
Contaminant Types: Pesticides
Sampling Medium: Edible fish and shellfish
Resource Protected: Human health
Sources: Compliance Policy Guide, Sec. 575.100, Pesticide Residues in Food and Feed - Enforcement Criteria
3. USEPA Recommended Screening Values
Contaminant Types: Pesticides, PAHs, PCBs, dioxins & furans, metals
Sampling Medium: Edible fish and shellfish
Resource Protected: Human health
Sources: EPA Guidance for Developing Fish Advisories (national and regional guidance);
Guidance for Assessing Chemical Contaminant Data for Use in Fish Advisories:
- Vol. 1, 3rd ed., Fish Sampling and Analysis (November 2000) EPA 823-B-00-007. See especially Ch. 5, Table 5-3 (Dose-response variables and recommended screening values for target analytes - Recreational fishers) and Table 5-4 (Dose-response variables and recommended screening values for target analytes - Subsistence fishers);
- Vol. 2, 3rd ed., Risk Assessment and Fish Consumption Limits (November 2000) EPA 823-B-00-008. See especially Ch. 4, risk-based consumption tables by contaminant.
4. USEPA database of U.S. State, Territory, and Tribal fish consumption advisories
Contaminant Types: Mercury, PCBs, chlordane, dioxins, DDT, other bioaccumulative contaminants
Sampling Medium: Edible fish and shellfish
Resource Protected: Human health
Sources: National Listing of Fish Advisories Database (2011 data); Search for Advisories Where You Live
1. Canadian Tissue Residue Guidelines for the Protection of Wildlife Consumers of Aquatic Biota
Contaminant Types: DDT, methylmercury, PCBs, dioxins & furans, toxaphene
Sampling Medium: Whole fish
Resource Protected: Fish-eating wildlife
Sources: Canadian Environmental Quality Guidelines (includes introductory text, fact sheets for individual contaminants, and the 1999 protocol for derivation of Canadian tissue residue guidelines for the protection of wildlife that consume aquatic biota); Canadian Environmental Quality Guidelines, Summary Table (online searchable database and access to downloadable Excel file)
2. New York Fish Flesh Criteria for Piscivorous Wildlife
Contaminant Types: PCBs, organochlorine pesticides, other chlorinated organic compounds
Sampling Medium: Whole fish
Resource Protected: Fish-eating wildlife
Sources: Niagara River Biota Contamination Project: Fish Flesh Criteria for Piscivorous Wildlife, Newell, A.J. et al., 1987; reprinted February 2000. New York State Department of Environmental Conservation Technical Report 87-3
3. Pesticide Whole-Fish Benchmark Ranges for Protection of Fish-Eating Wildlife, Compiled by the USGS National Water-Quality Assessment Program
Contaminant Types: Organochlorine pesticides
Sampling Medium: Whole fish
Resource Protected: Fish-eating wildlife
Sources: Pesticides in the Nation’s Streams and Ground Water, 1992–2001, Gilliom et. al. (2007), U.S. Geological Survey Circular 1291. See Appendix 3, Table B (benchmarks list); Derivation (see page 109)
Last updated: March 1, 2019
Follow the links below to learn more about USGS science on our Nation’s water quality.
National Water-Quality Assessment (NAWQA)
Groundwater Quality Research
Water Quality in the Nation’s Streams and Rivers – Current Conditions and Long-Term Trends
Public Supply Wells
Domestic (Private) Supply Wells
Predicting Groundwater Quality in Unmonitored Areas
Surface-Water Quality and Ecology
Drinking Water Taste and Odor
Below are data or web applications associated with this project.
Pesticide and transformation product concentrations and risk quotients in U.S. headwater streams
Dissolved Pesticides in Weekly Water Samples from the NAWQA Regional Stream Quality Assessments (2013-2017)
Below are publications associated with this project.
Groundwater quality in the Edwards-Trinity aquifer system
Groundwater quality in selected Stream Valley aquifers, western United States
Groundwater quality in the Colorado Plateaus aquifers, western United States
Groundwater-quality and select quality-control data from the National Water-Quality Assessment Project, January 2017 through December 2019
Inclusion of pesticide transformation products is key to estimating pesticide exposures and effects in small U.S. streams
Lithium in groundwater used for drinking-water supply in the United States
Pesticides and pesticide degradates in groundwater used for public supply across the United States: Occurrence and human-health context
Fluoride occurrence in United States groundwater
Biofilms provide new insight into pesticide occurrence in streams and links to aquatic ecological communities
The relation of geogenic contaminants to groundwater age, aquifer hydrologic position, water type, and redox conditions in Atlantic and Gulf Coastal Plain aquifers, eastern and south-central USA
Daily stream samples reveal highly complex pesticide occurrence and potential toxicity to aquatic life
Projected urban growth in the Southeastern USA puts small streams at risk
- Overview
How does the water quality measure up? It all depends on what the water will be used for and what contaminants are of interest. Water-quality benchmarks are designed to protect drinking water, recreation, aquatic life, and wildlife. Here you’ll find links to some of the most widely used sets of water, sediment, and fish tissue benchmarks and general guidance about their interpretation.
Featured: Updated Information on Groundwater Quality & BenchmarksNew USGS fact sheets update information on groundwater quality in the nation's most heavily used aquifers. Overall, inorganic constituents related to the interaction of groundwater and aquifer rocks most commonly exceed human-health benchmarks.
A water-quality benchmark is defined here as a threshold value against which measured concentrations can be compared to help assess the potential effects of contaminants on water quality. Benchmarks typically apply to a specific contaminant(s) in a specific sampling medium for a specific beneficial use:
-
Contaminant: contaminant classes for which benchmarks are available include pesticides, volatile organic compounds (VOC), pharmaceuticals, polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB), metals, and nutrients;
-
Sampling medium: drinking water, ambient surface water, bed sediment, whole fish, or edible fish tissue; and
-
Beneficial use: the use that the benchmark is designed to protect, for example, drinking water, recreation, aquatic life, or wildlife.
“Benchmark” is a generic term, and can include any of the following:
-
Standard or regulation: threshold values that are legally enforceable by agencies of the U.S. Government or Canada. Within the U.S., the National Primary Drinking Water Regulations (NPDWR) include standards and treatment techniques that apply to public water systems as part of the Safe Drinking Water Act (SDWA).
-
Guideline: threshold values that have no regulatory status but are issued in an advisory capacity.
-
Criteria: within the U.S., criteria are part of the definition of a water-quality standard in Sec 303(c) of the Clean Water Act (CWA). Also, 304(a) criteria are published values that reflect scientific knowledge on the effects of priority pollutants on health and welfare, including effects on aquatic life, plants, wildlife, shorelines, beaches, esthetics and recreation; the concentration and dispersal of pollutants or their byproducts; and the effects on biological community diversity, productivity, and stability (Section 304(a) of CWA).
This web page focuses on national-scale benchmarks established for freshwater systems in the United States or Canada. However, a few types of benchmarks from the States or the general scientific literature also are included, for particular sampling media and beneficial uses that have few or no national guidelines. Examples of these include whole-fish benchmarks for protection of wildlife, or human health benchmarks for pharmaceuticals.
Use of Benchmarks in Interpreting Water-Quality Data
Contaminant benchmarks can be used in screening-level assessments, in which site-specific estimates of contaminant exposure (concentrations or concentration statistics) determined from measurements of contaminants in various sampling media are compared to water-quality benchmarks. This approach has been used for many years by the USGS National Water Quality Program (such as in USGS Circular 1291, Pesticides in the Nation’s Stream and Ground Water 1992-2001), and it is similar in concept to U.S. Environmental Protection Agency (USEPA) screening-level assessments for pesticides, which USEPA uses in early stages of ecological risk assessments to evaluate the potential impact of pesticides to non-target organisms. Screening-level assessments are not a substitute for either risk assessments, which include many more factors (such as additional avenues of exposure), or site-specific studies of effects. Rather, comparisons of measured or estimated concentrations with water-quality benchmarks provide an initial perspective on the potential for adverse effects, as well as a framework for prioritizing additional investigations that may be warranted. Concentrations that exceed a benchmark do not necessarily indicate that adverse effects are occurring—they indicate that adverse effects might occur and that sites where benchmarks are exceeded may warrant further investigation. (See Characteristics and Limitations of Screening-Level Assessments section.) In general, effective use of benchmarks in water-quality assessment requires an understanding of how the benchmarks were derived and information about the specific hydrologic system being studied. Users are encouraged to consult the online sources for background information on the technical basis for the benchmarks being used, and any underlying assumptions, to better interpret what it means if a measured concentration exceeds a benchmark.
Benchmark Types and Sources
Click on the links below or scroll down the page to see specific benchmarks listed, with links to more information.
I. WATER COLUMN
A. DRINKING WATER
1. USEPA Drinking Water Regulations and Health Advisories
2. USEPA Human Health Benchmarks for Pesticides
3. USGS Health-Based Screening Levels
4. USEPA Regional Screening Levels for Chemical Contaminants at Superfund Sites
5. Canadian Guidelines for Drinking Water Quality
6. Minnesota Department of Health Pharmaceutical Water Screening ValuesB. AMBIENT SURFACE WATER
1. USEPA Ambient Water-Quality Criteria for the Protection of Human Health
2. USEPA Recreational Water-Quality Criteria
3. USEPA Ambient Water-Quality Criteria for the Protection of Aquatic Organisms
4. USEPA (Office of Pesticide Programs) Aquatic Life Benchmarks
5. Canadian Water Quality Guidelines for the Protection of Aquatic Life
6. State numeric water quality criteria for Nitrogen and Phosphorus
7. Aquatic life water quality criteria for selected pesticides
8. Pesticide Toxicity Index (2014 update): an additive model for pesticide mixturesII. BED SEDIMENT
A. WHOLE BED SEDIMENT
1. USEPA Equilibrium Partitioning Sediment Benchmarks
2. Canadian Interim Sediment Quality Guidelines
3. Consensus-Based Sediment Quality Guidelines
4. Chronic Toxicity Thresholds for Fipronil and Pyrethroid Pesticides in Sediment
5. Freshwater Sediment Benchmarks for Currently Used PesticidesIII. FISH AND SHELLFISH TISSUE
A. EDIBLE FISH AND SHELLFISH TISSUE
1. USEPA Tolerances
2. FDA Action Levels
3. USEPA Recommended Screening Values
4. USEPA database of U.S. State, Territory, and Tribal fish consumption advisoriesB. WHOLE FISH
1. Canadian Tissue Residue Guidelines for the Protection of Wildlife Consumers of Aquatic Biota
2. New York Fish Flesh Criteria for Piscivorous Wildlife
3. Pesticide Whole-Fish Benchmark Ranges for Protection of Fish-Eating Wildlife, Compiled by the
USGS National Water-Quality Assessment ProgramCharacteristics and Limitations of Screening-Level Assessments
Screening-level assessments are a first step toward addressing the question of whether contaminants are present at concentrations that may affect human health, aquatic life or wildlife. They provide a perspective on where effects are most likely to occur and what contaminants may be responsible. Screening-level assessments are primarily intended to identify and prioritize needs for further investigation and have the following characteristics and limitations:
- The benchmarks used in a screening-level assessment are selected to correspond to both the sampling medium (drinking water, ambient surface water, bed sediment, whole fish, or edible fish tissue) and the beneficial uses of the hydrologic system being studied (human health, aquatic life, or wildlife). More than one type of benchmark may be appropriate for some samples and some hydrologic systems (such as surface water from a stream that is used for drinking water and that also supports aquatic life).
- Many water-quality benchmarks selected for the screening-level assessment are estimates of no-effect levels, such that concentrations below the benchmarks are expected to have a low likelihood of adverse effects and concentrations above a benchmark have a greater likelihood of adverse effects, which generally increases with concentration. One exception is for sediment benchmarks, which sometimes come in pairs for a given contaminant; if so, typically the lower value defines concentrations below which adverse effects are not expected and the upper value defines concentrations above which adverse effects are likely.
- The presence of contaminants in environmental samples at concentrations that exceed benchmarks does not indicate that adverse effects are certain to occur. Conversely, concentrations that are below benchmarks do not guarantee that adverse effects will not occur but indicate that they are expected to be negligible—subject to the limitations of both benchmarks (e.g., underlying assumptions) and concentration measurements (e.g., analytical detection limits), and the assumption that effects of the contaminant are not unduly affected by environmental conditions or the presence of co-occurring contaminants.
- The potential for adverse effects of contaminants on humans, aquatic life, and fish-eating wildlife can only be partially addressed because monitoring studies typically analyze for a small fraction of all the contaminants that may be present in the environment. In addition, some contaminants do not have benchmarks available.
- Most water-quality benchmarks are based on toxicity tests of individual chemicals, whereas contaminants usually occur as mixtures. Comparisons to single-compound benchmarks may tend to underestimate the potential for adverse effects.
- Water-quality benchmarks for different contaminants and media are not always comparable because they have been derived by a number of different approaches, using a variety of types of toxicity values and test species.
- For some benchmarks, there is substantial uncertainty in underlying estimates of no-effect levels, depending on the methods used to derive them and the quantity and types of toxicity information on which they are based.
- Estimates of contaminant exposure derived from either measured or estimated concentrations are also uncertain—particularly for short-term exposure of aquatic organisms to pesticides in lotic systems (rivers and streams), which tends to be underestimated by periodic discrete sampling procedures.
Benchmark Types and Sources:
1. USEPA Drinking Water Regulations and Health Advisories
Contaminant Types: Microorganisms, disinfectants, disinfection byproducts, inorganic chemicals, organic chemicals, radionuclides
Sampling Medium: Drinking water
Resource Protected: Human health
Sources: National Primary Drinking Water Regulations (List of Contaminants and their MCLs), Drinking Water Standards and Advisory Tables (List of Contaminants and their MCLs, Health Advisories (HAs) and Cancer Risk Concentrations) (March 2018)
2. USEPA Human Health Benchmarks for Pesticides
Contaminant Types: Pesticides
Sampling Medium: Drinking water
Resource Protected: Human health
Sources: Human Health Benchmarks for Pesticides (available for food-use pesticides without drinking water regulations or health advisories) (2017), Supporting document: Human Health Benchmarks for Pesticides: Updated 2017 Technical Document (January 2017)
3. USGS Health-Based Screening Levels
Contaminant Types: Pesticides, hormones, pharmaceuticals, other emerging contaminants, volatile organic compounds (VOCs), semivolatile organic compounds (SVOCs), organochlorine compounds, trace elements, major ions, nutrients, radionuclides
Sampling Medium: Drinking water
Resource Protected: Human health
Sources: Health-Based Screening Levels for Evaluating Water-Quality Data (May 2018), Supporting document: Development and Application of Health-Based Screening Levels for Use in Water-Quality Assessments (2007), Updated 2018 Technical Information (May 2018)
4. USEPA Regional Screening Levels for Chemical Contaminants at Superfund Sites
Contaminant Types: Pesticides, PAHs, PCBs, other organic chemicals, inorganic chemicals
Sampling Medium: Drinking water (also available for soil and air)
Resource Protected: Human health
Sources: Regional Screening Levels (RSLs) (May 2018), RSLs Tables (May 2018), RSLs User Guide
5. Canadian Guidelines for Drinking Water Quality
Contaminant Types: Microorganisms, pesticides, other organic chemicals, inorganic chemicals, physical parameters, radionuclides
Sampling Medium: Drinking water
Resource Protected: Human health
Sources: Canadian Drinking Water Guidelines (August 2018), Guidelines for Canadian Drinking Water Quality, Summary Table (February 2017)
6. Minnesota Department of Health Pharmaceutical Water Screening Values
Contaminant Types: Pharmaceuticals
Sampling Medium: Drinking water
Resource Protected: Human health
Sources: Rapid Assessments for Pharmaceuticals Project, Pharmaceutical Water Screening Values Report, Download the table of screening values: Pharmaceutical Water Screening Table (July 2018)
1. USEPA Ambient Water-Quality Criteria for the Protection of Human Health
Contaminant Types: USEPA priority pollutants (organic and inorganic chemicals)
Sampling Medium: Ambient surface water
Resource Protected: Human health
Sources: National Recommended Water Quality Criteria
2. USEPA Recreational Water-Quality Criteria
Contaminant Types: Microorganisms/pathogens
Sampling Medium: Ambient surface water
Resource Protected: Human health/ recreation
Sources: 2012 Recreational Water Quality Criteria; Recreational Water Quality Criteria document, Office of Water 820-F-12-058 (2012); Draft Human Health Recreational Ambient Water Quality Criteria and/or Swimming Advisories for Microcystins and Cylindrospermopsin (2016)
3. USEPA Ambient Water-Quality Criteria for the Protection of Aquatic Organisms
Contaminant Types: USEPA priority pollutants (organic and inorganic chemicals)
Sampling Medium: Ambient surface water
Resource Protected: Aquatic life
Sources: National Recommended Water Quality Criteria
4. USEPA (Office of Pesticide Programs) Aquatic Life Benchmarks
Contaminant Types: Pesticides, pesticide degradates
Sampling Medium: Ambient surface water
Resource Protected: Aquatic life
Sources: Office of Pesticide Programs' Aquatic Life Benchmarks (October 2018)
5. Canadian Water Quality Guidelines for the Protection of Aquatic Life
Contaminant Types: Pesticides, PAHs, VOCs, other organic chemicals, metals, other inorganic chemicals
Sampling Medium: Ambient surface water
Resource Protected: Aquatic life
Sources: Canadian Environmental Quality Guidelines; Canadian Environmental Quality Guidelines, Summary Table (online searchable database and access to downloadable Excel file)
6. State numeric water quality criteria for Nitrogen and Phosphorus
Contaminant Types: Nutrients
Sampling Medium: Ambient surface water
Resource Protected: Multiple, including aquatic life, public health, navigation (impacts from eutrophication)
Sources: Numeric Nutrient Water Quality Criteria; State Progress Toward Developing Numeric Nutrient Water Quality Criteria for Nitrogen and Phosphorus (May 2018)
7. Aquatic life water quality criteria for selected pesticides (derived via the UC Davis method) (2012)
Contaminant Types: Organophosphate insecticides, pyrethroid insecticides, diuron
Sampling Medium: Ambient surface water
Resource Protected: Aquatic life
Sources: Aquatic Life Water Quality Criteria for Selected Pesticides: Tjeerdema, R.S., ed., 2012, Reviews of Environmental Contamination and Toxicology
8. Pesticide Toxicity Index (2014 update): an additive model for pesticide mixtures
Contaminant Types: Pesticides
Sampling Medium: Ambient surface water
Resource Protected: Aquatic life
Sources: Pesticide Toxicity Index: A Tool for Assessing Potential Toxicity of Pesticide Mixtures to Freshwater Aquatic Organisms, Nowell, L.H., et al., 2014, Science of the Total Environment, v. 476-477, p. 144-157.
1. USEPA Equilibrium Partitioning Sediment Benchmarks
Contaminant Types: Organochlorine pesticides, PAHs, other nonionic organic chemicals, metals
Sampling Medium: Bed sediment
Resource Protected: Benthic organisms
Sources: Equilibrium Partitioning Sediment Benchmarks (ESBs) for the Protection of Benthic Organisms: Procedures for the Determination of the Freely Dissolved Interstitial Water Concentrations of Nonionic Organics (2012): EPA/600/R-02/012:
Procedures for the Derivation of Equilibrium Partitioning Sediment Benchmarks (ESBs) for the Protection of Benthic Organisms:
Compendium of Tier 2 Values for Nonionic Organics. See Table C-1. (March 2008) EPA/600/R-02/016
Dieldrin (2003) EPA/600/R-02/0010,
Endrin (2003) EPA/600/R-02/009,
PAH Mixtures (November 2003) EPA/600/R-02/013,
Metal Mixtures (Cadmium, Copper, Lead, Nickel, Silver, and Zinc) (2005) EPA/600/R-02/0112. Canadian Interim Sediment Quality Guidelines
Contaminant Types: Organochlorine pesticides, PAHs, PCBs, metals
Sampling Medium: Bed sediment
Resource Protected: Aquatic Life
Sources: Canadian Environmental Quality Guidelines (includes introductory text, fact sheets for individual contaminants, and the 1999 protocol for derivation of Canadian sediment-quality guidelines for the protection of aquatic life); Canadian Environmental Quality Guidelines, Summary Table (online searchable database and access to downloadable Excel file)
3. Consensus-Based Sediment Quality Guidelines
Contaminant Types: Organochlorine pesticides, PAHs, PCBs, metals
Sampling Medium: Bed sediment
Resource Protected: Aquatic Life
Sources: Development and Evaluation of Consensus-Based Sediment Quality Guidelines for Freshwater Ecosystems. MacDonald, D.D. et al., 2000, Archives of Environmental Contamination and Toxicology, v. 39, p. 20-31; Prediction of Sediment Toxicity Using Consensus-Based Freshwater Sediment Quality Guidelines, Ingersoll, C.G. et al., 2001, Archives of Environmental Contamination and Toxicology, v. 41, p. 8-21.
4. Chronic Toxicity Thresholds for Fipronil and Pyrethroid Pesticides in Sediment
Contaminant Types: Fipronil and pyrethroid insecticides
Sampling Medium: Bed sediment
Resource Protected: Aquatic Life
Sources: Contaminants in Stream Sediments from Seven U.S. Metropolitan Areas: Data Summary of a National Pilot Study, Moran, P.W., et al., 2012, USGS SIR 2011-5092. See Table 13 for pesticide benchmark values and p. 19 of the text for the derivation. Available for pyrethroid and fipronil compounds
5. Freshwater Sediment Benchmarks for Currently Used Pesticides
Contaminant Types: Pesticides
Sampling Medium: Bed sediment
Resource Protected: Aquatic Life
Sources: Development and application of freshwater sediment-toxicity benchmarks for currently used pesticides, Nowell, L.H., et al., 2016, Science of the Total Environment, v. 550, p. 835-850.
III. FISH AND SHELLFISH TISSUE
A. EDIBLE FISH AND SHELLFISH TISSUE
Contaminant Types: Pesticides
Sampling Medium: Edible fish and shellfish
Resource Protected: Human health
Sources: Regulation of pesticide residues on Food (Information about EPA tolerances); Code of Federal Regulations, go to current year, Title 40, Chapter I, Part 180, Subpart C
Contaminant Types: Pesticides
Sampling Medium: Edible fish and shellfish
Resource Protected: Human health
Sources: Compliance Policy Guide, Sec. 575.100, Pesticide Residues in Food and Feed - Enforcement Criteria
3. USEPA Recommended Screening Values
Contaminant Types: Pesticides, PAHs, PCBs, dioxins & furans, metals
Sampling Medium: Edible fish and shellfish
Resource Protected: Human health
Sources: EPA Guidance for Developing Fish Advisories (national and regional guidance);
Guidance for Assessing Chemical Contaminant Data for Use in Fish Advisories:
- Vol. 1, 3rd ed., Fish Sampling and Analysis (November 2000) EPA 823-B-00-007. See especially Ch. 5, Table 5-3 (Dose-response variables and recommended screening values for target analytes - Recreational fishers) and Table 5-4 (Dose-response variables and recommended screening values for target analytes - Subsistence fishers);
- Vol. 2, 3rd ed., Risk Assessment and Fish Consumption Limits (November 2000) EPA 823-B-00-008. See especially Ch. 4, risk-based consumption tables by contaminant.
4. USEPA database of U.S. State, Territory, and Tribal fish consumption advisories
Contaminant Types: Mercury, PCBs, chlordane, dioxins, DDT, other bioaccumulative contaminants
Sampling Medium: Edible fish and shellfish
Resource Protected: Human health
Sources: National Listing of Fish Advisories Database (2011 data); Search for Advisories Where You Live
1. Canadian Tissue Residue Guidelines for the Protection of Wildlife Consumers of Aquatic Biota
Contaminant Types: DDT, methylmercury, PCBs, dioxins & furans, toxaphene
Sampling Medium: Whole fish
Resource Protected: Fish-eating wildlife
Sources: Canadian Environmental Quality Guidelines (includes introductory text, fact sheets for individual contaminants, and the 1999 protocol for derivation of Canadian tissue residue guidelines for the protection of wildlife that consume aquatic biota); Canadian Environmental Quality Guidelines, Summary Table (online searchable database and access to downloadable Excel file)
2. New York Fish Flesh Criteria for Piscivorous Wildlife
Contaminant Types: PCBs, organochlorine pesticides, other chlorinated organic compounds
Sampling Medium: Whole fish
Resource Protected: Fish-eating wildlife
Sources: Niagara River Biota Contamination Project: Fish Flesh Criteria for Piscivorous Wildlife, Newell, A.J. et al., 1987; reprinted February 2000. New York State Department of Environmental Conservation Technical Report 87-3
3. Pesticide Whole-Fish Benchmark Ranges for Protection of Fish-Eating Wildlife, Compiled by the USGS National Water-Quality Assessment Program
Contaminant Types: Organochlorine pesticides
Sampling Medium: Whole fish
Resource Protected: Fish-eating wildlife
Sources: Pesticides in the Nation’s Streams and Ground Water, 1992–2001, Gilliom et. al. (2007), U.S. Geological Survey Circular 1291. See Appendix 3, Table B (benchmarks list); Derivation (see page 109)
Last updated: March 1, 2019
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- Science
Follow the links below to learn more about USGS science on our Nation’s water quality.
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.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.Water 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.Public Supply Wells
Are you among the more than 100 million people in the U.S. who relies on a public-supply well for your drinking water? Although the quality of finished drinking water from public water systems is regulated by the EPA, long-term protection and management of the raw groundwater tapped by public-supply wells requires an understanding of the occurrence of contaminants in this invisible, vital resource...Domestic (Private) Supply Wells
More than 43 million people—about 15 percent of the U.S. population—rely on domestic (private) wells as their source of drinking water. The quality and safety of water from domestic wells are not regulated by the Federal Safe Drinking Water Act or, in most cases, by state laws. Instead, individual homeowners are responsible for maintaining their domestic well systems and for monitoring water...Predicting Groundwater Quality in Unmonitored Areas
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.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.Drinking Water Taste and Odor
Some water is just unpleasant to drink—it’s cloudy, or it smells or tastes bad. Some drinking water discolors teeth or skin, stains laundry or plumbing fixtures, or corrodes or clogs pipes. These effects are caused when some naturally occurring constituents occur at concentrations high enough to be a nuisance, and are particularly common where groundwater is used as a drinking water supply. - Data
Below are data or web applications associated with this project.
Pesticide and transformation product concentrations and risk quotients in U.S. headwater streams
This dataset includes a subset of previously released pesticide data (Morace and others, 2020) from the U.S. Geological Survey (USGS) National Water Quality Assessment Program (NAWQA) Regional Stream Quality Assessment (RSQA) project and the corresponding hazard index results calculated using the R package toxEval, which are relevant to Mahler and others, 2020. Pesticide and transformation productDissolved Pesticides in Weekly Water Samples from the NAWQA Regional Stream Quality Assessments (2013-2017)
Dissolved pesticides were measured in weekly water samples from 482 wadeable streams in five regions of the United States during 2013-2017, as part of the U.S. Geological Survey's (USGS) Regional Stream Quality Assessment (RSQA). One study was conducted each year, starting with the Midwest (2013), followed by the Southeast Piedmont (2014), Pacific Northwest (2015), Northeast (2016), and Central Ca - Publications
Below are publications associated with this project.
Filter Total Items: 13Groundwater quality in the Edwards-Trinity aquifer system
Groundwater provides nearly 50 percent of the Nation’s drinking water. To help protect this vital resource, the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Project assesses groundwater quality in aquifers that are important sources of drinking water. The Edwards-Trinity aquifer system constitutes one of the important aquifers being evaluated.AuthorsMaryLynn MusgroveGroundwater quality in selected Stream Valley aquifers, western United States
Groundwater provides nearly 50 percent of the Nation’s drinking water. To help protect this vital resource, the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Project assesses groundwater quality in aquifers that are important sources of drinking water. The Stream Valley aquifers constitute one of the important aquifer systems being evaluated.AuthorsJames A. KingsburyGroundwater quality in the Colorado Plateaus aquifers, western United States
Groundwater provides nearly 50 percent of the Nation’s drinking water. To help protect this vital resource, the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Project assesses groundwater quality in aquifers that are important sources of drinking water. The Colorado Plateaus aquifers constitute one of the important areas being evaluated.AuthorsJames R. Degnan, MaryLynn MusgroveGroundwater-quality and select quality-control data from the National Water-Quality Assessment Project, January 2017 through December 2019
Groundwater-quality environmental data were collected from 983 wells as part of the National Water-Quality Assessment Project of the U.S. Geological Survey National Water Quality Program and are included in this report. The data were collected from six types of well networks: principal aquifer study networks, which are used to assess the quality of groundwater used for public water supply; land-usAuthorsJames A. Kingsbury, Laura M. Bexfield, Terri Arnold, MaryLynn Musgrove, Melinda L. Erickson, James R. Degnan, Anthony J. Tesoriero, Bruce D. Lindsey, Kenneth BelitzInclusion of pesticide transformation products is key to estimating pesticide exposures and effects in small U.S. streams
Improved analytical methods can quantify hundreds of pesticide transformation products (TPs), but understanding of TP occurrence and potential toxicity in aquatic ecosystems remains limited. We quantified 108 parent pesticides and 116 TPs in more than 3 700 samples from 442 small streams in mostly urban basins across five major regions of the United States. TPs were detected nearly as frequently aAuthorsBarbara Mahler, Lisa H. Nowell, Mark W. Sandstrom, Paul Bradley, Kristin Romanok, Christopher Konrad, Peter Van MetreByEcosystems Mission Area, Water Resources Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, California Water Science Center, New Jersey Water Science Center, Oklahoma-Texas Water Science Center, South Atlantic Water Science Center (SAWSC), Washington Water Science Center, National Water Quality LaboratoryLithium in groundwater used for drinking-water supply in the United States
Lithium concentrations in untreated groundwater from 1464 public-supply wells and 1676 domestic-supply wells distributed across 33 principal aquifers in the United States were evaluated for spatial variations and possible explanatory factors. Concentrations nationwide ranged from <1 to 396 μg/L (median of 8.1) for public supply wells and <1 to 1700 μg/L (median of 6 μg/L) for domestic supply wellsAuthorsBruce D. Lindsey, Kenneth Belitz, Charles A. Cravotta, Patricia Toccalino, Neil M. DubrovskyPesticides and pesticide degradates in groundwater used for public supply across the United States: Occurrence and human-health context
This is the first assessment of groundwater from public-supply wells across the United States to analyze for >100 pesticide degradates and to provide human-health context for degradates without benchmarks. Samples from 1204 wells in aquifers representing 70% of the volume pumped for drinking supply were analyzed for 109 pesticides (active ingredients) and 116 degradates. Among the 41% of wells wheAuthorsLaura M. Bexfield, Kenneth Belitz, Bruce D. Lindsey, Patricia Toccalino, Lisa H. NowellFluoride occurrence in United States groundwater
Data from 38,105 wells were used to characterize fluoride (F) occurrence in untreated United States (U.S.) groundwater. For domestic wells (n = 11,032), water from which is generally not purposely fluoridated or monitored for quality, 10.9% of the samples have F concentrations >0.7 mg/L (U.S. Public Health Service recommended optimal F concentration in drinking water for preventing tooth decay) (8AuthorsPeter B. McMahon, Craig J. Brown, Tyler D. Johnson, Kenneth Belitz, Bruce D. LindseyBiofilms 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 MayThe relation of geogenic contaminants to groundwater age, aquifer hydrologic position, water type, and redox conditions in Atlantic and Gulf Coastal Plain aquifers, eastern and south-central USA
Groundwater age distributions developed from carbon-14 (14C), tritium (3H), and helium-4 (4He) concentrations, along with aquifer hydrologic position, water type, and redox conditions, were compared to geogenic contaminants of concern (GCOC) from 252 public-supply wells in six Atlantic and Gulf Coastal Plain unconsolidated-sediment aquifers. Concentrations of one or more GCOCs in 168 (67%) wellsAuthorsJames R. Degnan, Bruce D. Lindsey, Joseph Patrick Levitt, Zoltan SzaboDaily stream samples reveal highly complex pesticide occurrence and potential toxicity to aquatic life
Transient, acutely toxic concentrations of pesticides in streams can go undetected by fixed-interval sampling programs. Here we compare temporal patterns in occurrence of current-use pesticides in daily composite samples to those in weekly composite and weekly discrete samples of surface water from 14 small stream sites. Samples were collected over 10–14 weeks at 7 stream sites in each of the MidwAuthorsJulia E. Norman, Barbara Mahler, Lisa H. Nowell, Peter C. Van Metre, Mark W. Sandstrom, Mark A. Corbin, Yaorong Qian, James F. Pankow, Wentai Luo, Nicholas B. Fitzgerald, William E. Asher, Kevin J. McWhirterProjected 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 urbanizing Piedmont ecoregion of the southeastern USAuthorsPeter C. Van Metre, Ian R. Waite, Sharon L. Qi, Barbara Mahler, Adam Terando, Michael Wieczorek, Michael R. Meador, Paul M. Bradley, Celeste A. Journey, Travis S. Schmidt, Daren Carlisle