Water pollution in the United States is a growing problem that became critical in the 19th century with the development of mechanized agriculture, mining, and manufacturing industries—although laws and regulations introduced in the late 20th century have improved water quality in many water bodies. Extensive industrialization and rapid urban growth exacerbated water pollution combined with a lack of regulation has allowed for discharges of sewage, toxic chemicals, nutrients, and other pollutants into surface water. This has led to the need for more improvement in water quality as it is still threatened and not fully safe.
In the early 20th century, communities began to install drinking water treatment systems, but control of the principal pollution sources—domestic sewage, industry, and agriculture—was not effectively regulated in the US until the 1970s. These pollution sources can affect both groundwater and surface water. Multiple pollution incidents such as the Kingston Fossil Plant coal fly ash slurry spill (2008) and the Deepwater Horizon oil spill (2010) have left lasting impacts on water quality, ecosystems, and public health in the United States. The United States Geological Survey (USGS) reported in 2023 that at least 45% of drinking water in the United States contains per- and polyfluoroalkyl substances (PFAS), commonly referred to as "forever chemicals." The Environmental Protection Agency (EPA) has been able to identify around 70,000 water bodies that do not meet revised water quality standards due to PFAS.
Many solutions to water pollution in the United States can be implemented to curtail water pollution: municipal wastewater treatment, agricultural and industrial wastewater treatment, erosion and sediment control, and the control of urban runoff. The continued implementation of pollution prevention, control, and treatment measures are used to pursue the goal of maintaining water quality within levels specified in federal and state regulations; however, many water bodies across the country continue to violate water quality standards in the 21st century.
Overview
Water pollution was identified as a growing problem in the US by scientists, government officials and the public in the 19th century. During that era many cities and towns piped their untreated domestic sewage into nearby waterways. Wastewater discharged by factories, mines and other businesses increased as the economy expanded. Large cities, and later smaller communities, began to install drinking water treatment systems in the early 20th century, but sewage treatment plants were limited at that time and not very effective. Effective control of sewage and industrial pollution was not comprehensively addressed until later in the century. Agricultural pollution emerged as a growing problem in the 20th century with the increased mechanization of agriculture and increasing use of chemicals.
Following the passage of the 1972 Clean Water Act (CWA), the levels of water pollution in US waterways generally have experienced a dramatic decrease with respect to sewage outflow and many types of industrial wastewater. The 1972 law didn't address surface runoff from farms or urban runoff pollution. Municipal stormwater runoff became subject to federal regulation in 1987, although implementation of the requirements by cities and towns has been a slow and difficult process. About half of U.S. stream and river miles continue to violate federal water quality standards in the 21st century. Surveys of lakes, ponds and reservoirs indicated that about 70 percent were impaired (measured on a surface area basis), and a little more than 70 percent of the nation's coastlines, and 90 percent of the surveyed ocean and near coastal areas were also impaired. A related 2017 EPA report on the nation's water quality stated that 46% of river and stream miles, 21% of the nation's lakes, 18% of coastal and Great Lakes waters, and 32% of the nation's wetland areas are in "poor biological condition." In the 21st century many water bodies continue to be degraded by discharges from agriculture, certain industries, and urban runoff, which often leads to environmental and human health risks.
While the CWA has helped improve water quality in many areas of the United States, the law does not fully address all aspects of pollution. Many think that Congress should revise or expand the law to address these problems and gaps in regulation. Although the CWA has been effective in controlling point source pollution (where the discharge is typically via a pipe or ditch and assigning responsibility for mitigation is straightforward), it has not been as effective with nonpoint sources (where discharges are diffuse, and treatment or prevention may be technically difficult or very expensive).
Despite the negative health and ecosystem impacts of water pollution, solutions exist that are able to treat and decrease pollution levels in water bodies.
Types Surface water pollution Surface water consists of all forms of visible water sources, such as oceans, lakes, and rivers. Currently, a significant percentage of surface freshwater sources are polluted in the United States. This poses a huge threat to American water sources because over 60% of water used in the United States is from these freshwater sources. A majority of freshwater contamination cases are a result of nutrient pollution, which is the result of farm waste and fertilizer entering water bodies, creating zones with depleted oxygen levels.
Groundwater pollution Groundwater is rainfall that collects in porous spaces deep underground, which are called aquifers. Humans can access the water that collects in an aquifer by building wells to pump the water to the surface for use. About 40% of drinking water in America comes from groundwater sources. When contaminants enter aquifers, the pollution spreads, eliminating the potential to use the aquifer for drinking water. Groundwater contamination is often the result of chemicals that seep through the soil and into the water supply, such as pesticides and fertilizers. Other causes of contamination in groundwater includes gasoline, oil, road salts, septic tank waste, or leakage from landfills.
Categories of pollution sources
Point source Point source pollution occurs when water pollution contamination comes from a single source. Point sources could include leaking septic tanks, oil spills, dumping of waste, or wastewater treatment facilities. To prevent point source pollution from occurring, the Clean Water Act regulates what can be discharged into a water body by requiring each facility to obtain a National Pollutant Discharge Elimination System (NPDES) permit.
Nonpoint source Nonpoint source pollution occurs when the contamination derives from multiple different sources. This type of pollution is very challenging to manage given that the original source(s) may be difficult to identify. Nonpoint source pollution is the most common type of pollution because as rainfall runs off of land on its path to different water sources, it becomes contaminated by pollutants from the surrounding area. These sources include agriculture related pollutants, urban runoff, or drainage. The CWA does not authorize the issuance of NPDES permits for nonpoint sources.
Trans-boundary sources Trans-boundary water pollution occurs when pollution in one country's waters spreads and damages another country's environment or water supply. Trans-boundary pollution can travel through rivers or ocean currents. This means that this type of pollution is not contained within the boundaries of a nation. Trans-boundary pollution can allow pollution to travel across large distances because of how it accesses natural waterways.
Causes of pollution Municipal sewage
Historically, municipal sewage was a major contributor of water pollution across the United States. The lack of proper treatment of sewage resulted in many contaminated water bodies across the country. Domestic sewage became a widespread problem with the onset of the industrial revolution in the 19th century, population growth, and increasing urbanization. Through the early 20th century, most communities had no sewage treatment plants or waste disposal sites. Some cities built sewer pipes which carried their sewage to a nearby river or coastal area, but lacked any treatment of the wastes, instead depositing the sewage directly into the water. The first wastewater treatment plants were built in the late 19th and early 20th centuries in the United States and typically didn't fully treat the waste.
The extensive construction of new and upgraded sewage treatment systems following the passage of the 1972 Clean Water Act has greatly reduced the impacts of municipal discharges. Since the 1980s secondary treatment has been the national standard for municipalities.EPA. "Secondary Treatment Regulation." Code of Federal Regulations, Since these advancements, the United States has been able to process around 34 billion gallons of wastewater per day. Some individual systems continue to cause localized water quality problems due to outdated or leaking piping and collection systems, leading to combined sewer overflows and sanitary sewer overflows. Poor upkeep of sewer infrastructure results in contamination from leaks, and such practices contributed to a rating from the American Society of Civil Engineers of a "D" grade for America's wastewater infrastructure in 2017. While all domestic wastewater is now treated nationwide, leaks and spills of municipal sewage pose a significant problem because wastewater carries diseases like salmonella, hepatitis, and many other infectious diseases that roughly sickens 3.5 million Americans every year.
Sewage is not a waste product and it can be converted into wealth economically in a circular economy by using the aquatic life cycle of mosquitoes and non-biting midges. Organic matter in the sewage is consumed and transformed as adult mosquitoes and midges which can be used as fish/poultry meal.
Urban runoff
Water research during the late 1970s and 1980s indicated that stormwater runoff was a significant cause of water quality impairment in many parts of the US.For example, see the Nationwide Urban Runoff Program (1979–83). Research on stormwater pollution continues in the 21st century, with findings that urban runoff is an ongoing source of water quality problems nationwide. Increased land development throughout the country—in both cities and suburbs—has led to an increase in impervious surfaces (parking lots, roads, buildings, compacted soil), which generates increased surface runoff during wet weather. The development of new roads and hardscape surfaces continue to contribute to the pollution of nearby rivers, lakes, and coastal areas. Typical runoff pollutants include gasoline, oil and other motor vehicle fluids; metals; fertilizers; pesticides and other chemicals.
Industrial pollution Early indications of pollution from industrial waste in the United States existed since the 1870s, increasing as the Industrial Revolution and Second Industrial Revolution expanded throughout the United States and its environmental impacts were observed more frequently. Industrial wastes contribute toxic pollutants and chemicals and can have detrimental ecosystem and public health impacts if discharged directly into surface water.
Growth of industrialization and industrial waste