The Clean Water Act (CWA) is the primary federal law in the United States governing water pollution. Its objective is to restore and maintain the chemical, physical, and biological integrity of the nation's waters; recognizing the responsibilities of the states in addressing pollution and providing assistance to states to do so, including funding for publicly owned treatment works for the improvement of wastewater treatment; and maintaining the integrity of wetlands.[2]
The Clean Water Act was one of the United States' first and most influential modern environmental laws. Its laws and regulations are primarily administered by the U.S. Environmental Protection Agency (EPA) in coordination with state governments, though some of its provisions, such as those involving filling or dredging, are administered by the U.S. Army Corps of Engineers. Its implementing regulations are codified at 40 C.F.R. Subchapters D, N, and O (Parts 100–140, 401–471, and 501–503).
Technically, the name of the law is the Federal Water Pollution Control Act.[3] The first FWPCA was enacted in 1948, but took on its modern form when completely rewritten in 1972 in an act entitled the Federal Water Pollution Control Act Amendments of 1972.[4][1] Major changes have subsequently been introduced via amendatory legislation including the Clean Water Act of 1977[5] and the Water Quality Act (WQA) of 1987.[6]
The Clean Water Act does not directly address groundwater contamination. Groundwater protection provisions are included in the Safe Drinking Water Act, Resource Conservation and Recovery Act, and the Superfund act.
Contamination of drinking water supplies can not only occur in the source water but also in the distribution system. Sources of water contamination include naturally occurring chemicals and minerals (arsenic, radon, uranium), local land use practices (fertilizers, pesticides, concentrated feeding operations), manufacturing processes, and sewer overflows or wastewater releases. Some examples of health implications of water contamination are gastrointestinal illness, reproductive problems, and neurological disorders. Infants, young children, pregnant women, the elderly, and people whose immune systems are compromised because of AIDS, chemotherapy, or transplant medications, may be especially susceptible to illness from some contaminants.[7]
Gastrointestinal disorders include such conditions as constipation, irritable bowel syndrome, hemorrhoids, anal fissures, perianal abscesses, anal fistulas, perianal infections, diverticular diseases, colitis, colon polyps and cancer.[8] In general, children and the elderly are at highest risk for gastrointestinal disease. In a study investigating the association between drinking water quality and gastrointestinal illness in the elderly of Philadelphia, scientists found water quality 9 to 11 days before the visit was negatively associated with hospital admissions for gastrointestinal illness, with an interquartile range increase in turbidity being associated with a 9% increase . The association was stronger in those over 75 than in the population aged 65–74. This example is a small reflection of residents of the United States remain at risk of waterborne gastrointestinal illness under current water treatment practices.[9]
Reproductive problems refer to any illness of the reproductive system. New research by Brunel University and the University of Exeter strengthens the relationship between water pollution and rising male fertility problems. Study identified a group of chemicals that act as anti-androgens in polluted water, which inhibits the function of the male hormone, testosterone, reducing male fertility.[10]
Neurological disorders are diseases of the brain, spine and the nerves that connect them. The new study of more than 700 people in California's Central Valley found that those who likely consumed contaminated private well water had a higher rate of Parkinson's. The risk was 90 percent higher for those who had private wells near fields sprayed with widely used insecticides. Unlike water supplies in large cities, private wells are mostly unregulated and are not monitored for contaminants. Many of them exist at shallow depths of less than 20 yards, and some of the crop chemicals used to kill pests and weeds can flow into ground water. Therefore, private wells are likely to contain pesticides, which can attack developing brains (womb or infancy), leading to neurological diseases later in life. A study led by UCLA epidemiology professor Beate Ritz suggests that "people with Parkinson's were more likely to have consumed private well water, and had consumed it on average 4.3 years longer than those who did not have the disease."[11]
Under the current Supreme Court rule issued in 2023, all waters (such as streams, oceans, rivers and lakes) with "a continuous surface connection" to "navigable waters" are covered under the CWA.[12]
The 1972 statute frequently uses the term "navigable waters" but also defines the term as "waters of the United States, including the territorial seas."[13] Regulations interpreting the 1972 law have included water features such as intermittent streams, playa lakes, prairie potholes, sloughs and wetlands as "waters of the United States." In 2006, in Rapanos v. United States, a plurality of the US Supreme Court authored by Justice Antonin Scalia held that the term "waters of the United States" "includes only those relatively permanent, standing or continuously flowing bodies of water 'forming geographic features' that are described in ordinary parlance as 'streams[,]... oceans, rivers, [and] lakes.'" The concurrent written opinion of Justice Anthony Kennedy defined the term more broadly, including wetlands with a "significant nexus" to traditionally-defined navigable waters.[14] Since Rapanos, the EPA and the U.S. Army Corps of Engineers have attempted to define protected waters in the context of Rapanos through the 2015 Clean Water Rule, but this has been highly controversial. The agencies considered the CWA to cover bodies of water with a "significant nexus" with traditional navigable waters, according with Justice Kennedy's definition.
In 2023, the Supreme Court rejected the "significant nexus" test in Sackett v. EPA and established the current definition.
The CWA introduced the National Pollutant Discharge Elimination System (NPDES), a permit system for regulating point sources of pollution.[15] Point sources include:
Point sources may not discharge pollutants to surface waters without an NPDES permit. The system is managed by EPA in partnership with state environmental agencies. EPA has authorized 47 states to issue permits directly to the discharging facilities. The CWA also allows tribes to issue permits, but no tribes have been authorized by EPA. In the remaining states and territories, the permits are issued by an EPA regional office.[17] (See Titles III and IV.)
In legislation prior to 1972, Congress had authorized states to develop water quality standards, which would limit discharges from facilities based on the characteristics of individual water bodies. However, those standards were to be developed only for interstate waters, and the science to support that process (i.e. data, methodology) was in the early stages of development. That system was not effective, and there was no permit system in place to enforce the requirements. In the 1972 CWA, Congress added the permit system and a requirement for technology-based effluent limitations.[18]
In the 2020 Supreme Court case County of Maui v. Hawaii Wildlife Fund, the Court also validated that some discharges may not be point sources, but are the "functional equivalent of a direct discharge" to navigable waters, such as in this case, the injection of wastewater into groundwater injection wells. As of the time of the case's decision, this was not an area the EPA has established regulations for, and the Court instructed the EPA to work with the courts to define such functional equivalents. The Court wrote that this would likely depend most on the distance the pollutants traveled and time to reach navigable waters, with consideration for the material that the pollutants traveled through, any physical or chemical interaction of the pollutants with components in the ground, and how much of the pollutant makes it to the navigable water.[19] In July 2021, following the Supreme Court decision, the Hawaii District Court determined that the Maui County sewage treatment plant's groundwater injection of sewage was the "functional equivalent of a direct discharge" and required the plant to obtain an NPDES permit.[20]
The 1972 CWA created a new requirement for technology-based standards for point source discharges. EPA develops those standards for categories of dischargers, based on the performance of pollution control technologies without regard to the conditions of a particular receiving water body. The intent of Congress was to create a "level playing field" by establishing a basic national discharge standard for all facilities within a category, using a "Best Available Technology." The standard becomes the minimum regulatory requirement in a permit. If the national standard is not sufficiently protective at a particular location, then water quality standards may be employed, and the permit authority (state or EPA) will include water quality-based effluent limitations in the permit.[21]: 1–3
The 1972 act authorized continued use of the water quality-based approach, but in coordination with the technology-based standards. After application of technology-based standards to a permit, if water quality is still impaired for the particular water body, then the permit agency may add water quality-based limitations to that permit. The additional limitations are to be more stringent than the technology-based limitations and would require the permittee to install additional controls. Water quality standards consist of four basic elements: 1) Designated uses; 2) Water quality criteria; 3) Antidegradation policy and 4) General policies.[22]
The water quality standards regulations require states and federally recognized tribes/nations to specify appropriate uses for water bodies in their jurisdiction. Identification of appropriate water uses takes into consideration the usage and value of public water supply, protection of fish, wildlife, recreational waters, agricultural, industrial and navigational water ways. Suitability of a water body is examined by states and tribes/nations usages based on physical, chemical, and biological characteristics. States and tribes/nations also examine geographical settings, scenic qualities and economic considerations to determine fitness of designated uses for water bodies. If those standards indicate designated uses to be less than those currently attained, states or tribes are required to revise standards to reflect the uses that are actually being attained. For any body of water with designated uses that do not include "fishable/swimmable" target use that is identified in section 101(a)(2) of CWA, a "Use Attainability Analysis" must be conducted. Every three years, such bodies of water must be re-examined to verify if new information is available that demand a revision of the standard. If new information is available that specify "fishable/swimmable" uses can be attained, the use must be designated.[22]
States and federally recognized Indigenous Nations protect their designated areas by adopting water quality criteria that the EPA publishes under CWA section 304(a), modifying the criteria to reflect site-specific conditions or adopting criteria based on other scientifically defensible methods. Water quality criteria can be numeric criteria that toxicity causes are known for protection against pollutants. A narrative criterion is water quality criteria which serves as a basis for limiting the toxicity of waste discharges to aquatic species. A biological criterion is based on the aquatic community which describes the number and types of species in a water body. A nutrient criterion solely protects against nutrient over enrichment, and a sediment criterion describes conditions of contaminated and uncontaminated sediments to avoid undesirable effects.[22]
The water quality regulations include an anti-degradation policy that requires states and tribes to establish a three-tiered anti-degradation program. Anti-degradation procedures identify steps and questions that need to be addressed when specific activities affect water quality. "Tier 1" requirements are applicable to all surface waters. These requirements maintain and protect current uses and the water quality conditions to support existing uses. Current uses are identified by showing that fishing, swimming, and other water uses have occurred and are suitable since November 28, 1975. "Tier 2" requirements maintains and protects water bodies with existing conditions that are better to support "fishable/swimmable" uses pursuant to CWA section 101(a)(2). "Tier 3" requirements maintain and protect water quality in "outstanding national resource waters" (ONRWs), which are the highest quality waters in the US with ecological significance.[22]
States and Native American tribes also adopt general policies pertaining to water quality standards that are subject to review and approval by the EPA. Those provisions on water quality standards include mixing zones, variance, and low flow policies. Mixing zone policy is defined area surrounding a point source discharge where sewage is diluted by water. Methodology of mixing zone procedure determines the location, size, shape and quality of mixing zones. Variance policy temporarily relax water quality standard and are alternatives to removing a designated use. States and tribes may include variance as part of their water quality standard. Variance is subject to public review every three years and warrant development towards improvement of water quality. The "Low Flow" policy pertains to states and tribes water quality standards that identify procedures applied to determining critical low flow conditions.[22]
Most NPDES permittees are required to collect samples of their wastewater and analyze the samples using test methods specified in their permits.[21] EPA publishes analytical methods that are used by the permittees. The procedures identify chemical compounds and microbiological components of wastewater, as required by the act.[23] Some of the chemical compound test procedures include the chemical detection of trace elements such as cancer-causing metals.[24] Some microbiological test procedures use microbial source tracking (MST) techniques to calculate and identify biological and chemical trends that may support new regulatory limits on pollutants.[25]
Congress exempted some water pollution sources from the point source definition in the 1972 CWA and was unclear on the status of some other sources. Such sources were therefore considered to be nonpoint sources that were not subject to the permit program.
Agricultural stormwater discharges and irrigation return flows were specifically exempted from permit requirements.[27] Congress, however, provided support for research, technical and financial assistance programs at the U.S. Department of Agriculture to improve runoff management practices on farms. See Natural Resources Conservation Service.