Environmental Protection Agency Action Research Articles

A pilot study characterizing tetrachloroethylene exposure with exhaled breath in an impacted community

Martinsville, Indiana overlays four groundwater contamination plumes, including a U.S. Environmental Protection Agency (EPA)-designated Superfund site. The primary contaminants are tetrachloroethylene (PCE), trichloroethylene (TCE), and other volatile organic compounds (VOCs). Martinsville represents many similar communities facing the challenge of groundwater and soil contamination and vapor intrusion, where residents are often frustrated by the lack of help in understanding and addressing the problem. The objective of this study was to evaluate PCE in exhaled breath to identify and quantify exposure to PCE and to explore the extent and level of PCE exposure among community residents. We measured chlorinated VOCs in exhaled breath samples from 38 healthy individuals who lived either in a contamination area or outside any plume area. We also measured VOCs in indoor air and tap water samples collected from 10 homes. PCE was detected in all exhaled breath samples (mean: 6.6 μg/m3; range: 1.9–44 μg/m3) and tap water samples (mean: 0.74 μg/L; range: 0.39–0.92 μg/L). PCE was detected in six of nine (66%) homes with air concentrations ranging from 1.6 to 70 μg/m3, exceeding the EPA action level of 42 μg/m3. We did not detect TCE or any other chlorinated VOCs in these samples. PCE exposure occurred among individuals living on the EPA Superfund site, as well as among those living on other plume sites and those living outside any known plumes. Preventive measures should focus on identifying highly exposed groups and reducing their exposures, followed by addressing moderately elevated exposures in the community. Our results demonstrated that PCE in exhaled breath can be used as an effective tool in community engaged environmental health research to evaluate the extent and level of community exposure, increase awareness, and promote residents’ participation in research and site cleanup decision-making.

Method for analysis of environmental lead contamination in soils.

A method for lead (Pb) detection in soil is presented. Pb is a dangerous environmental pollutant that is present in soils, posing a health risk to millions of people worldwide, and regular monitoring of Pb contamination in soils is essential to public health. Many sensitive methods for detection of heavy metals in solid matrices exist, but they cannot be performed on-site because they are costly (>$30 per sample), require trained personnel, and many classical sample preparation methods are not safe to bring into the field. We describe an alternative process, combining a safer sample preparation method with electrochemical analysis. The process requires minimal training, making it an attractive overall method for regular environmental screening of Pb in soils. Extract obtained from the soil is pH adjusted and analyzed using a stencil-printed carbon electrode and square wave anodic stripping voltammetry. In this work, a study of 15 neighborhood soils examining the concentration of Pb present post-extraction was performed to demonstrate the method. The limit of detection for the electrochemical analysis was calculated to be 16 ppb-well below the United States Environmental Protection Agency's action limit for Pb in soils (400 mg kg-1 or 4000 ppb)-and third party inductively coupled plasma-optical emission spectroscopy analysis validated the results obtained in this study to within ±17% on average.

Predictors of Water Lead Levels in Drinking Water of Homes With Domestic Wells in 3 Illinois Counties.

Millions of US homes receive water from private wells, which are not required to be tested for lead (Pb). An approach to prioritizing high-risk homes for water lead level (WLL) testing may help focus outreach and screening efforts, while reducing the testing of homes at low risk. To (1) characterize distribution of WLLs and corrosivity in tap water of homes with private residential wells, and (2) develop and evaluate a screening strategy for predicting Pb detection within a home. Cross-sectional. Three Illinois counties: Kane (northern), Peoria (central), and Jackson (southern). 151 private well users from 3 Illinois counties. Water samples were analyzed for WLL and corrosivity. (1) WLL and corrosivity, and (2) the sensitivity, specificity, and predictive value of a strategy for prioritizing homes for WLL testing. Pb was detected (>0.76 ppb) in tap water of 48.3% homes, and 3.3% exceeded 15 ppb, the US Environmental Protection Agency action level for community water systems. Compared with homes built in/after 1987 with relatively low corrosivity, older homes with more corrosive water were far more likely to contain measurable Pb (odds ratio = 11.07; 95% confidence interval, 3.47-35.31). The strategy for screening homes with private wells for WLL had a sensitivity of 88%, specificity of 42%, positive predictive value of 58%, and negative predictive value of 80%. Pb in residential well water is widespread. The screening strategy for prioritizing homes with private wells for WLL testing is greater than 85% sensitive.

Developing an Ion-Selective Electrode Membrane Sensor to Detect Lead Levels in Drinking Water

Lead contamination in drinking water is often a close-to-home contamination caused by corroded lead service pipes connecting households to main lines or lead-based pluming within the households. This is particularly evident in houses built prior to 1986 when the United States Environmental Protection Agency (EPA) amended the Safe Drinking Water Act (SDWA) to prohibit the use of any lead-based pipe. Despite the legally established action limit of lead level of 15 parts-per-billion (ppb) in drinking water, incidents with disastrous consequences have occurred repeatedly (e.g. water crisis in Flint, Michigan). The objective of this research is to develop a polymeric ion-selective electrode (ISE) for the detection of lead levels at the EPA action level, or 10-9 molar concentration (M). Primarily, various ratios of sodium tetraphenylborate, resin powder, and lead-selective ionophore were considered and investigated to accomplish this goal. Two commercially available ionophores (Dibenzo-18-Crown-6 and Tert-Butylcalix(4)Arene-Tetrakis) were investigated as well as a synthesized poly (AN-co-HSA) copolyaniline ionophore. The commercially available ionophores were able to consistently achieve a limit of detection (LOD) of 10-6 M when used for the ISE electrode while the synthesized ionophore showed a less consistent LOD between 10-6 M and 10-9 M.

Trace Analysis of Heavy Metals (Cd, Pb, Hg) Using Native and Modified 3D Printed Graphene/Poly(Lactic Acid) Composite Electrodes

AbstractHere we investigate the use of 3D printed graphene/poly(lactic acid) (PLA) electrodes for quantifying trace amounts of Hg, Pb, and Cd. We prepared cylindrical electrodes by sealing a 600 μm diameter graphene/PLA filament in a pipette tip filled with epoxy. We characterized the electrodes using scanning electron microscopy, Raman spectroscopy, and cyclic voltammetry in ferrocene methanol. The physical characterization showed a significant amount of disorder in the carbon structure and the electrochemical characterization showed quasi‐reversible behavior without any electrode pretreatment. We then used unmodified graphene/PLA electrode to quantify Hg, and Pb and Cd in 0.01 M HCl and 0.1 M acetate buffer using square wave anodic stripping voltammetry. We were able to quantify Hg with a limit of detection (LOD) of 6.1 nM (1.2 ppb), but Pb and Cd did not present measurable peaks at concentrations below ∼400 nM. We improved the LODs for Pb and Cd by depositing Bi microparticles on the graphene/PLA and, after optimization, achieved clear stripping peaks at the 20 nM level for both ions (4.1 and 2.2 ppb for Pb2+ and Cd2+, respectively). The results obtained for all three metals allowed quantification below the US Environmental Protection Agency action limits in drinking water.

Studies of radiation health effects inform EPA actions

In 1970, the US Environmental Protection Agency (EPA) was given the responsibility to provide guidance to other federal agencies in the formulation of radiation protection standards. To carry out its federal guidance responsibilities and protect human health, the EPA must estimate risk at low doses to limit the risk of radiogenic cancers from environmental exposures. These risk estimates are based on models which conform to the linear no threshold (LNT) hypothesis. A cancer risk model conforms to the LNT hypothesis if the excess risk of cancer at low doses increases approximately proportional to dose, with no threshold. Risk models with a linear-quadratic dose response can satisfy the LNT hypothesis. Based on careful review of evidence from epidemiological and radiobiological studies, authoritative scientific bodies have repeatedly endorsed the use of LNT models for estimating and regulating risk and concluded that despite uncertainties at low dose and dose rates, the LNT model remains the most practical and implementable model for radiation protection. This article describes the rationale underlying the use of LNT models for calculating risk for low dose and dose rate exposures and discusses some of the epidemiological evidence which inform on its continued use.

Vulnerable Populations Exposed to Lead-Contaminated Drinking Water within Houston Ship Channel Communities.

Recent events have drawn increased attention to potential lead exposures from contaminated drinking water. Further, homes with older infrastructure are at greatest risk due to the presence of the disinfectant chemical chloramine, which can leach lead from older pipes. There is a growing need to determine the extent of lead leaching especially within vulnerable communities and homes with children. This pilot study collected survey data and performed lead analysis on drinking water in the small community of Manchester in Houston, TX. Manchester is characterized by industrial sites, flooding, and a low socioeconomic population. Surveys and water analyses were completed on randomly selected homes (N = 13) and documented perceptions of participants on their drinking water regarding presence and concentration of lead. Lead was discovered in 30.8% of homes ranging from 0.6 to 2.4 (µg/L), all below the US Environmental Protection Agency action level of 15 ppb, but above the water standard goals. These findings further suggest that contaminated water is a broad issue requiring concerted efforts to ensure the health of US residents.

Successes and Challenges in Implementation of Radon Control Activities in Iowa, 2010-2015.

BackgroundRadon gas has recently become more prominent in discussions of lung cancer prevention nationally and in Iowa. A review in 2013 of cancer plans in the National Comprehensive Cancer Control Program found that 42% of cancer plans, including Iowa’s, had terminology on radon. Plans included awareness activities, home testing, remediation, policy, and policy evaluation.Community ContextIowa has the highest average radon concentrations in the United States; 70% of homes have radon concentrations above the Environmental Protection Agency’s action levels. Radon control activities in Iowa are led by the Iowa Cancer Consortium, the Iowa Department of Public Health, and the Iowa Radon Coalition.MethodsA collaborative approach was used to increase levels of awareness, testing, and (if necessary) mitigation, and to introduce a comprehensive radon control policy in Iowa by engaging partners and stakeholders across the state.OutcomeThe multipronged approach and collaborative work in Iowa appears to have been successful in increasing awareness: the number of radon tests completed in Iowa increased by 20% from 19,600 in 2009 to 23,500 in 2014, and the number of mitigations completed by certified mitigators increased by 108% from 2,600 to more than 5,400.InterpretationThrough collaboration, Iowa communities are engaged in activities that led to increases in awareness, testing, mitigation, and policy. States interested in establishing a similar program should consider a multipronged approach involving multiple entities and stakeholders with different interests and abilities. Improvements in data collection and analysis are necessary to assess impact.

Lung Cancer Risk from Radon in Marcellus Shale Gas in Northeast U.S. Homes.

The amount of radon in natural gas varies with its source. Little has been published about the radon from shale gas to date, making estimates of its impact on radon-induced lung cancer speculative. We measured radon in natural gas pipelines carrying gas from the Marcellus Shale in Pennsylvania and West Virginia. Radon concentrations ranged from 1,520 to 2,750 Bq/m3 (41-74 pCi/L), and the throughput-weighted average was 1,983 Bq/m3 (54 pCi/L). Potential radon exposure due to the use of Marcellus Shale gas for cooking and space heating using vent-free heaters or gas ranges in northeastern U.S. homes and apartments was assessed. Though the measured radon concentrations are higher than what has been previously reported, it is unlikely that exposure from natural gas cooking would exceed 1.2 Bq/m3 (<1% of the U.S. Environmental Protection Agency's action level). Using worst-case assumptions, we estimate the excess lifetime (70 years) lung cancer risk associated with cooking to be 1.8×10-4 (interval spanning 95% of simulation results: 8.5×10-5 , 3.4×10-4 ). The risk profile for supplemental heating with unvented gas appliances is similar. Individuals using unvented gas appliances to provide primary heating may face lifetime risks as high as 3.9×10-3 . Under current housing stock and gas consumption assumptions, expected levels of residential radon exposure due to unvented combustion of Marcellus Shale natural gas in the Northeast United States do not result in a detectable change in the lung cancer death rates.

1. United States

In 2015, his penultimate full year in office, President Barack Obama moved aggressively to make the United States a leader in global efforts to combat climate change. The United States provided strong support for the negotiations that produced the Paris Agreement in December 2015. The US Environmental Protection Agency (EPA) adopted significant regulations to limit greenhouse gas (GHG) emissions from power plants and to clarify the reach of federal authority to protect wetlands. Fierce opposition from Republicans in Congress failed to curtail EPA actions due to Obama’s veto of resolutions disapproving the regulations. Even a Supreme Court decision requiring the EPA to consider costs before limiting emissions of mercury and air toxics standards was founded on such narrow grounds that the EPA was able to leave the regulations in place. The Republican Party, which fiercely opposes environmental regulation, now holds a majority in both houses of Congress. However, its majority is not large enough to over-ride a presidential veto, which requires a two-thirds majority in each house of Congress. Congress does hold the ‘power of the purse,’ but, fearing political backlash from another government shutdown, Republicans were unable to de-fund the EPA’s environmental initiatives. The future of President Obama’s environmental initiatives will thus depend on decisions by courts hearing legal challenges to them and, ultimately, the results of the 2016 elections.

Radon Testing: Community Engagement By a Rural Family Medicine Office.

Iowa has the highest average radon concentrations in the nation, with an estimated 400 radon-induced lung cancer deaths each year. Radon is the second leading cause of lung cancer death overall. The objectives of this study were (1) to educate the population attending a family medicine office about the dangers of radon, (2) to encourage homeowners to test for radon, (3) to work with the community to identify resources for mitigation, and (4) to assess the utility of working with a local family medicine office as a model that could be adopted for other communities with high home radon concentrations. Participants obtained a US Environmental Protection Agency-certified activated charcoal short-term radon kit through their primary care office or by attending a seminar held by their medical office. Participants completed a short investigator-developed questionnaire about their home, heating, and demographics. Of 746 radon kits handed out, 378 valid results (51%) were received, of which 351 questionnaires could be matched to the kit results. The mean radon result was 10.0 pCi/L (standard deviation, 8.5 pCi/L). A radon result of 4 pCi/L or higher, the Environmental Protection Agency action level for mitigation, was found in 81% of homes (n = 285). Four of 5 homes tested had elevated radon levels. This family medicine office/university collaborative educational model could be useful for educating patients about other environmental dangers.

Incidence of waterborne lead in private drinking water systems in Virginia.

Although recent studies suggest contamination by bacteria and nitrate in private drinking water systems is of increasing concern, data describing contaminants associated with the corrosion of onsite plumbing are scarce. This study reports on the analysis of 2,146 samples submitted by private system homeowners. Almost 20% of first draw samples submitted contained lead concentrations above the United States Environmental Protection Agency action level of 15 μg/L, suggesting that corrosion may be a significant public health problem. Correlations between lead, copper, and zinc suggested brass components as a likely lead source, and dug/bored wells had significantly higher lead concentrations as compared to drilled wells. A random subset of samples selected to quantify particulate lead indicated that, on average, 47% of lead in the first draws was in the particulate form, although the occurrence was highly variable. While flushing the tap reduced lead below 15 μg/L for most systems, some systems experienced an increase, perhaps attributable to particulate lead or lead-bearing components upstream of the faucet (e.g., valves, pumps). Results suggest that without including a focus on private as well as municipal systems it will be very difficult to meet the existing national public health goal to eliminate elevated blood lead levels in children.

Associations of Indoor Home Radon Levels with Marcellus Shale Development

Associations of Indoor Home Radon Levels with Marcellus Shale DevelopmentAbstract Number:2487 Joan A. Casey*, Joseph DeWalle, Paul A. Locke, and Brian S. Schwartz Joan A. Casey* Johns Hopkins Bloomberg School of Public Health, United States, E-mail Address: [email protected] Search for more papers by this author , Joseph DeWalle Geisinger Health System Search for more papers by this author , Paul A. Locke Johns Hopkins Bloomberg School of Public Health, E-mail Address: [email protected] Search for more papers by this author , and Brian S. Schwartz Johns Hopkins Bloomberg School of Public Health and Geisinger Health System, E-mail Address: [email protected] Search for more papers by this author AbstractBackground: Radon causes around 21,000 lung cancer deaths annually in the United States. Most exposure occurs in the home when radon gas infiltrates from rocks and soils through openings. Recent drilling and hydraulic fracturing activity in Pennsylvania may have created new pathways allowing entrainment of radon into homes in a state where many homes already exceed the Environmental Protection Agency (EPA) action level of 4piC/L. Aims: To evaluate associations of proximity to Marcellus shale wells, by stage of development, with home radon levels.Methods: We located Marcellus shale wells and homes with indoor radon level readings using Pennsylvania Department of Environmental Protection data from 2006-2013. We used multilevel linear regression with a random intercept for home to assess associations of proximity to Marcellus shale in various stages of drilling with home radon levels while accounting for potential confounders (season of year, home type [e.g. duplex, apartment], area of home tested [e.g. basement, first floor], and geologic types).Results: There were 399,163 radon tests in 232,726 homes from 2006-2013. The median radon level was 3.3piC/L (interquartile range, 1.5 to 7.4) and 47% of homes had at least one radon reading over the EPA action level. On average, each home had 1.7 readings. There were 6973 Marcellus wells drilled in 39 of the state’s 67 counties over the study period, with 97% drilled after 2008. We will estimate exposure by the proximity of the closest drilled and stimulated well at the time of radon measurement and by an inverse- squared gravity model that will take into account all drilled and stimulated wells in the study area. Multilevel models will be used to estimate associations between the timing of Marcellus shale drilling and fracturing and concurrent indoor home radon level measurements.Conclusions: This research will inform upon potential radiation exposures due to hydraulic fracturing.

Consequences for Cleanup: EPA Gets Serious About Weak Watershed Improvement Plans

In a landmark series of reports issued on June 26, 2014, the Environmental Protection Agency (EPA) put the seven jurisdictions that pollute the Chesapeake Bay on notice that their plans for reducing nitrogen, phosphorous, and sediment fall short of where they must be to make cleanup by 2025 a reality. By EPA’s reckoning, Pennsylvania and Delaware were furthest off the mark, but Maryland, New York, Virginia, and West Virginia face EPA action if they fail to substantially improve their plans. Of the seven jurisdictions, only Washington, D.C. escaped serious criticism.

Have Regulatory Efforts to Reduce Organophosphorus Insecticide Exposures Been Effective?

Background: The Food Quality Protection Act (FQPA) was signed into law in 1996 to strengthen the regulation of pesticide tolerances in food. Organophosphorus (OP) insecticides were the first group of pesticides reviewed by the U.S. Environmental Protection Agency (EPA) under the new law.Objective: Our goal was to determine whether urinary concentrations of dialkylphosphate (DAP) metabolites of OP pesticides declined between the National Health and Nutrition Examination Survey (NHANES) III and NHANES 1999–2004.Methods: Using mass spectrometry–based methods, we analyzed urine samples from a nationally representative sample of 2,874 adults 20–59 years of age in NHANES 1999–2004 and samples from a non-nationally representative sample of 197 adult participants for NHANES III (1988–1994) for six common DAP metabolites of OP pesticides.Results: Median urinary DAP concentrations decreased by more than half between NHANES III and NHANES 2003–2004. Reductions of about 50%–90% were also observed for 95th percentile concentrations of five of the six metabolites. Frequencies of detection (FODs) decreased in all six metabolites (< 50% reduction). On average, median and 95th percentile concentrations and FODs showed a larger decrease in diethylphosphate metabolites than dimethylphosphate metabolites.Conclusions: Human exposure to OP insecticides as assessed by urinary DAP concentrations has decreased since the implementation of the FQPA, although we cannot be certain that U.S. EPA actions in response to the FQPA directly caused the decrease in DAP concentrations.

Residential Radon Appears to Prevent Lung Cancer

Residential radon has been found to be associated with lung cancer in epidemiological/ecological studies and the researchers have inappropriately concluded that residential radon causes lung cancer. Their conclusion relates to the linear-no-threshold (LNT) hypothesis-based, risk-assessment paradigm; however, the LNT hypothesis has been invalidated in numerous studies. It is shown in this paper that our hormetic relative risk (HRR) model is consistent with lung cancer data where detailed measurements of radon in each home were carried out. Based on the HRR model, low-level radon radioactive progeny is credited for activated natural protection (ANP) against lung cancer including smoking-related lung cancer. The proportion B(x) (benefit function) of ANP beneficiaries increases as the average radon level x increases to near the Environmental Protection Agency's action level of 4 picocuries/L (approximately 150 Bq m(-3)). As the average level of radon increases to somewhat above the action level, ANP beneficiaries progressively decrease to zero (B(x) decreases to 0), facilitating the occurrence of smoking-related lung cancers as well as those related to other less important risk factors. Thus, residential radon does not appear to cause lung cancer but rather to protect, in an exposure-level-dependent manner, from its induction by other agents (e.g., cigarette-smoke-related carcinogens).

EPA's Proposed Biotech Policy Turns a Deaf Ear to Science

Nina Fedoroff,* Robert Haselkorn, and Bruce M. Chassy *Huck Institutes of the Life Sciences, Penn State University, University Park, Pennsylvania, USA; King Abdullah, University of Science and Technology (KAUST), Thuwal, Saudi Arabia; Dept of Molecular Genetics & Cell Biology, The University of Chicago, Chicago, Illinois, USA; and Department of Food Science and Human Nutrition University of Illinois at Urbana-Champaign, Urbana, Illinois, USA

A Response to: Deadly Radon in Montana?

Dr. Hart intended to answer the question of whether or not radon is deadly in Montana. Instead he answered the question, “Do Environmental Protection Agency (EPA) county zone designations correlate to statistically different rates of lung cancer deaths in Montana?” Based on a non-significant student t-test comparing mean cancer mortality for EPA zone 1 and 2 designated counties, Dr. Hart concluded the “notion” that radon is deadly in Montana should be questioned. Dr. Hart’s analysis is flawed. Dr. Hart used the age-adjusted mortality rates from the National Cancer Institute (2010a) but excluded lung cancer deaths for individuals 65 years and older. Excluding data from the full range required justification conceptually, clinically, and analytically. Figure 1 illustrates the Montana counties with non-suppressed cases when the age restriction was removed. In addition, the mortality rates were not adjusted for smoking rate, environmental tobacco smoke, air-pollution particulate matter days, use of wood as a primary indoor heating source, medical sources of ionizing radiation, or access to care—all confounders for a meaningful analysis. I would direct Dr. Hart to the “interpret” link on the National Cancer Institute webpage for their explanation for geographic variations in cancer mortality rates (National Cancer Institute, 2010b). Despite these analytical errors, Dr. Hart does raise an interesting question about the accuracy of the EPA zone designations. FIG. 1 The EPA zone designations were derived from a prediction model based on indoor radon measurements, local geology, aerial radioactivity, soil permeability, and foundation type. Assigning each county into one of three zones for radon potential was a process required by the Indoor Radon Abatement Act of 1988 (EPA 2010). Zone 1 is the highest designation with a predicted indoor radon screening level average of greater than 4 picocuries per liter (pCi/L); the current EPA action level. Zone 2 is defined as moderate potential with an average indoor radon concentration between 2 and 4 pCi/L. Zone 3 is defined as low potential with an average indoor radon concentration less than 2 pCi/L. Forty-nine of Montana’s 56 counties are designated as zone 1 and seven are designated as zone 2. Therefore, none of the counties in Montana could be described, as Dr. Hart did, as low radon counties. It is important to note that these designations are guidelines and the U.S. Surgeon General and the EPA recommended that every home should be tested regardless of geographic location (EPA 2010). The broader issue Dr. Hart engaged was the issue of lung cancer mortality from radon. The President’s Cancer Panel (2009) recently reported that the cancer risk attributable to residential radon exposure has been clearly demonstrated and must be better addressed (p. xiv). The Panel recommended the EPA consider lowering its current radon action level. It is noteworthy that the World Health Organization (WHO) recently set their recommended action level to the equivalent of 2.7 pCi/L (WHO 2009). I would direct Dr. Hart to the list of distinguished references provided by both the President’s Cancer Panel as well as the World Health Organization regarding the cumulative evidence in support of their recommendations. Lung cancer, and potentially leukemia (Smith et al. 2007), skin, stomach, and liver cancers, result from protracted radon exposure (Pawel and Puskin 2003). Lung cancer is now the leading cause of cancer death among American women and radon exposure is the leading cause of lung cancer for people who do not smoke (Centers for Disease Control and Prevention 2010). Reducing preventable radon exposure is a goal common to the Healthy People 2010 (U.S. Department of Health and Human Services 2010b) and 2020 Programs (U.S. Department of Health and Human Services 2010a), WHO (2009), the President’s Cancer Panel (2009) and the Montana Cancer Control Coalition (2009). It is time for the allied health-care community to quiet the debate about the carcinogenicity of radon and focus instead on initiatives to reduce or eliminate preventable, unintentional radon exposure.

New directions in pollution control: the “Transport Rule”

New directions in pollution control: the “Transport Rule”

Clean water strategy

The U.S. Environmental Protection Agency (EPA) is inviting the public to comment on a draft strategy to protect and restore lakes, streams, and coastal waters. The document, “Coming together for clean water: EPA's strategy for achieving clean water,” outlines the agency's plans to address the United States' critical water stressors, sources, and threats.The document outlines several approaches the agency has identified, including systematically assessing the nation's waters to provide a baseline for tracking progress; increasing the focus on protecting healthy waters; enhancing EPA's ability to restore degraded waters and ecosystems; and reducing pollution. Specific EPA actions include completing national aquatic resource surveys; developing metrics to create a national list of healthy watersheds; strengthening the National Pollutant Discharge Elimination System; and encouraging integrated water management approaches and green infrastructure.