A change in the chemical, physical, biological, and radiological quality of water that is injurious to its existing, intended, or potential uses (for example, boating, waterskiing, swimming, the consumption of fish, and the health of aquatic organisms and ecosystems). The term “water pollution” generally refers to human-induced (anthropogenic) changes to water quality. Thus, the discharge of toxic chemicals from a pipe or the release of livestock waste into a nearby water body is considered pollution. Conversely, nutrients that originate from animals in the wild or toxins that originate from natural processes are not considered pollution.
The contamination of ground water, rivers, lakes, wetlands, estuaries, and oceans can threaten the health of humans and aquatic life. Sources of water pollution are generally divided into two categories. The first is point-source pollution, in which contaminants are discharged from a discrete location. Sewage outfalls and oil spills are examples of point-source pollution. The second category is non-point-source or diffuse pollution, referring to all of the other discharges that deliver contaminants to water bodies. Acid rain and unconfined runoff from agricultural or urban areas are examples of non-point-source pollution. The principal contaminants of water include toxic chemicals, nutrients and biodegradable organics, and bacterial and viral pathogens.
Water pollution can threaten human health when pollutants enter the body via skin exposure or through the direct consumption of contaminated food or drinking water. Priority pollutants, including dichlorodiphenyl trichloroethane (DDT) and polychlorinated biphenyls (PCBs), persist in the natural environment and bioaccumulate in the tissues of aquatic organisms. These persistent organic pollutants are transferred up the food chain (in a process called biomagnification), and they can reach levels of concern in fish species that are eaten by humans. Finally, bacteria and viral pathogens can pose a public health risk for those who drink contaminated water or eat raw shellfish from polluted water bodies. See also Environmental toxicology; Food web.
Contaminants have a significant impact on aquatic ecosystems. for example, enrichment of water bodies with nutrients (principally nitrogen and phosphorus) can result in the growth of algae and other aquatic plants that shade or clog streams. If wastewater containing biodegradable organic matter is discharged into a stream with inadequate dissolved oxygen, the water downstream of the point of discharge will become anaerobic and will be turbid and dark. Settleable solids, if present, will be deposited on the streambed, and anaerobic decomposition will occur. Over the reach of stream where the dissolved-oxygen concentration is zero, a zone of putrefaction will occur with the production of hydrogen sulfide, ammonia, and other odorous gases. Because many fish species require a minimum of 4–5 mg of dissolved oxygen per liter of water, they will be unable to survive in this portion of the stream.
Direct exposures to toxic chemicals is also a health concern for individual aquatic plants and animals. Chemicals (e.g., pesticides) are frequently transported to lakes and rivers via runoff, and they can have unintended and harmful effects on aquatic life. Toxic chemicals have been shown to reduce the growth, survival, reproductive output, and disease resistance of exposed organisms. These effects can have important consequences for the viability of aquatic populations and communities. See also Insecticide.
Wastewater discharges are most commonly controlled through effluent standards and discharge permits. Under this system, discharge permits are issued with limits on the quantity and quality of effluents. Water-quality standards are sets of qualitative and quantitative criteria designed to maintain or enhance the quality of receiving waters. Receiving waters are divided into several classes depending on their uses, existing or intended, with different sets of criteria designed to protect uses such as drinking water supply, bathing, boating, fresh-water and shellfish harvesting, and outdoor sports for seawater. For toxic compounds, chemical-specific or whole-effluent toxicity studies are used to develop standards and criteria. In the chemical-specific approach, individual criteria are used for each toxic chemical detected in the wastewater. Criteria can be developed to protect aquatic life against acute and chronic effects and to safeguard humans against deleterious health effects, including cancer. In the whole-effluent approach, toxicity or bioassay tests are used to determine the concentration at which the wastewater induces acute or chronic toxicity effects. See also Hazardous waste; Sewage disposal; Sewage treatment.
|Modern Science: water pollution|
water pollutionThe addition of harmful chemicals to natural water. Sources of water pollution in the United States include industrial waste, runoff from fields treated with chemical fertilizers, and runoff from areas that have been mined.
|Britannica Concise Encyclopedia: water pollution|
|US History Encyclopedia: Water Pollution|
Extensive water pollution in the United States began in the nineteenth century as a result of urbanization, industrial development, and modern agricultural practices. Although lumbering and mining despoiled individual lakes and rivers, the nation’s cities were the sites of the most severe pollution. Early industrial by-products joined human sewage and animal waste to foul drinking water supplies. By the early 1800s, even horses declined New York City’s public water, and one quarter of Boston’s wells produced undrinkable water. Severe epidemics of the waterborne diseases cholera and typhoid fever swept through major cities, most notably New York in 1832.
The early response to such pollution was not so much to clean the water but rather to build reservoirs and aqueducts to import fresh water for direct delivery to neighborhoods and even some individual homes. Cities built large sewer systems to flush these waters away, usually either out to sea or down a near by river. Sewers thus spread the previously more localized pollution, often fouling the water sources of other cities.
In the 1890s, scientists decisively linked many diseases, including typhoid and cholera, to the presence of human waste in water supplies. Cities began to filter their drinking water with remarkable results. The national urban death rate from typhoid, 36 per 100,000 in 1900, dropped to only 3 per 100,000 by 1935 and was virtually nonexistent by the twentieth century’s end. The urban water projects that combined filtration, delivery, and disposal ranked among the largest public works projects in the nation’s history. Chicago, for example, reversed the direction of the Chicago and Calumet Rivers, so by 1900 they no longer carried the city’s waste into Lake Michigan, its primary source of fresh water. By the end of the twentieth century, New York City moved about 1.5 billion gallons of fresh water through more than 300 miles of aqueducts and 27 artificial lakes.
The industrial pollution of bodies of water not used for drinking proved more difficult to control. In 1912, Congress charged the Public Health Service (PHS) with investigating water pollution. Two years later, the PHS established the first water quality standards. In the 1920s, the service investigated industrial pollution but with little effect. State governments retained the primary responsibility for water regulation. Following the lead of Pennsylvania, many states sought to balance environmental quality with the needs of industry by giving relatively high protection to waters used for drinking supplies while allowing others to be freely used for waste disposal. New Deal programs provided significant federal funds to water pollution control, and over the course of the 1930s the population served by sewage treatment nearly doubled. But those programs left pollution control in the hands of state governments.
After World War II, continued urban pollution and runoff from artificial fertilizers increasingly used in agriculture degraded the water quality of many lakes. Eutrophication occurs when plants and bacteria grow at abnormally high rates due to elevated quantities of nitrogen or phosphorus. The decomposition of this elevated biomass consumes much of the water’s oxygen, often leading to a cascade of changes in aquatic ecosystems. Many species of fish grow scarce or die off altogether, and algae “blooms” can make water unsafe to swim in or to drink. Although small urban lakes suffered from eutrophication as early as the 1840s, after World War II, population growth, increasing nitrogen-rich agricultural runoff, and the addition of phosphates to detergents polluted even bodies of water as large as Lake Erie. By 1958, the bottom portion of a 2,600-square-mile portion of the lake was completely without oxygen, and algae grew in mats two feet thick over hundreds of square miles more. The nation’s economic prosperity intensified problems, as pollution from heavy industry made some rivers and streams lifeless. In the 1960s, Cleveland authorities pronounced the Cuyahoga River a fire hazard, and at the end of the decade the river actually caught on fire. The more mobile and long-lasting industrial products polluted even waters remote from cities and industry. DDT, other pesticides and synthetic chemicals, mercury, and acid rain threatened numerous species and previously unaffected lakes and streams.
Such manifestations of a deepening pollution crisis prompted environmentalists and lawmakers to redouble pollution-control efforts. The major response, the 1972 Clean Water Act, shifted responsibility for the nation’s waterways and water supply to the federal government. In the following decades, federal funds and regulations issued under the act’s authority significantly raised standards for water purity. Repeatedly amended, the act halted the rate of water pollution, even in the face of decades of population and economic growth. Most industries and municipalities greatly reduced their pollution discharges, with the consequent reversal of the eutrophication of many bodies of water, including Lake Erie. Nevertheless, “non-point” pollution sources, such as agricultural runoff and vehicle exhaust, continued to degrade water quality. The act made virtually no progress in improving groundwater contamination. At the end of the twentieth century, regulating groundwater quality and grappling with nonpoint pollution remained the most formidable obstacles to those seeking to reverse water pollution.
Elkind, Sarah S. Bay Cities and Water Politics: The Battle for Resources in Boston and Oakland. Lawrence: University Press of Kansas, 1998.
Melosi, Martin V. The Sanitary City: Urban Infrastructure in America from Colonial Times to the Present. Baltimore: Johns Hopkins University Press, 2000.
Outwater, Alice. Water: A Natural History. New York: Basic Books, 1996.
|Columbia Encyclopedia: water pollution,|
In the United States industry is the greatest source of pollution, accounting for more than half the volume of all water pollution and for the most deadly pollutants. Some 370,000 manufacturing facilities use huge quantities of freshwater to carry away wastes of many kinds. The waste-bearing water, or effluent, is discharged into streams, lakes, or oceans, which in turn disperse the polluting substances. In its National Water Quality Inventory, reported to Congress in 1996, the U.S. Environmental Protection Agency concluded that approximately 40% of the nation’s surveyed lakes, rivers, and estuaries were too polluted for such basic uses as drinking supply, fishing, and swimming. The pollutants include grit, asbestos, phosphates and nitrates, mercury, lead, caustic soda and other sodium compounds, sulfur and sulfuric acid, oils, and petrochemicals.
In addition, numerous manufacturing plants pour off undiluted corrosives, poisons, and other noxious byproducts. The construction industry discharges slurries of gypsum, cement, abrasives, metals, and poisonous solvents. Another pervasive group of contaminants entering food chains is the polychlorinated biphenyl (PCB) compounds, components of lubricants, plastic wrappers, and adhesives. In yet another instance of pollution, hot water discharged by factories and power plants causes so-called thermal pollution by increasing water temperatures. Such increases change the level of oxygen dissolved in a body of water, thereby disrupting the water’s ecological balance, killing off some plant and animal species while encouraging the overgrowth of others.
Other Sources of Water Pollution
Towns and municipalities are also major sources of water pollution. In many public water systems, pollution exceeds safe levels. One reason for this is that much groundwater has been contaminated by wastes pumped underground for disposal or by seepage from surface water. When contamination reaches underground water tables, it is difficult to correct and spreads over wide areas. In addition, many U.S. communities discharge untreated or only partially treated sewage into the waterways, threatening the health of their own and neighboring populations.
Along with domestic wastes, sewage carries industrial contaminants and a growing tonnage of paper and plastic refuse (see solid waste). Although thorough sewage treatment would destroy most disease-causing bacteria, the problem of the spread of viruses and viral illness remains. Additionally, most sewage treatment does not remove phosphorus compounds, contributed principally by detergents, which cause eutrophication of lakes and ponds. Excreted drugs and household chemicals also are not removed by present municipal treatment facilites, and can be recycled into the drinking water supply.
Rain drainage is another major polluting agent because it carries such substances as highway debris (including oil and chemicals from automobile exhausts), sediments from highway and building construction, and acids and radioactive wastes from mining operations into freshwater systems as well as into the ocean. Also transported by rain runoff and by irrigation return-flow are animal wastes from farms and feedlots, a widespread source of pollutants impairing rivers and streams, groundwater, and even some coastal waters. Antibiotics, hormones, and other chemicals used to raise livestock are components of such animal wastes. Pesticide and fertilizer residues from farms also contribute to water pollution via rain drainage.
Large and small craft significantly pollute both inland and coastal waters by dumping their untreated sewage. Oil spilled accidentally or flushed from tankers and offshore rigs (900,000 metric tons annually) sullies beaches and smothers bird, fish, and plant life. In 1989 in one of the world’s worst single instances of water pollution, the Exxon Valdez spilled 11 million gallons of oil in Prince William Sound, Alaska, causing great environmental destruction. In 1997, the 22 oil spills reported worldwide involved a total of 15 million gallons (57 million liters) of oil. In addition to its direct damage to wildlife, oil takes up fat-soluble poisons like DDT, allowing them to be concentrated in organisms that ingest the oil-contaminated water; thus such poisons enter the food chains leading to sea mammals and people (see ecology).
Both DDT, which has been banned in the United States since 1972, and PCBs are manufactured in many parts of the world and are now widespread in the Atlantic and Pacific oceans. In addition, tarry oil residues are encountered throughout the Atlantic, as are styrofoam and other plastic rubbish. Plastic bits litter sections of the Pacific as far north as Amchitka Island near Alaska. Garbage, solid industrial wastes, and sludge formed in sewage treatment, all commonly dumped into oceans, are other marine pollutants found worldwide, especially along coastal areas.
Dangers of Water Pollution
Virtually all water pollutants are hazardous to humans as well as lesser species; sodium is implicated in cardiovascular disease, nitrates in blood disorders. Mercury and lead can cause nervous disorders. Some contaminants are carcinogens. DDT is toxic to humans and can alter chromosomes. PCBs cause liver and nerve damage, skin eruptions, vomiting, fever, diarrhea, and fetal abnormalities. Along many shores, shellfish can no longer be taken because of contamination by DDT, sewage, or industrial wastes.
Dysentery, salmonellosis, cryptosporidium, and hepatitis are among the maladies transmitted by sewage in drinking and bathing water. In the United States, beaches along both coasts, riverbanks, and lake shores have been ruined for bathers by industrial wastes, municipal sewage, and medical waste. Water pollution is an even greater problem in the Third World, where millions of people obtain water for drinking and sanitation from unprotected streams and ponds that are contaminated with human waste. This type of contamination has been estimated to cause more than 3 million deaths annually from diarrhea in Third World countries, most of them children.
Legislation and Control
The United States has enacted extensive federal legislation to fight water pollution. Laws include the Federal Water Pollution Control Act (1972), the Marine Protection, Research, and Sanctuaries Act (1972), the Safe Drinking Water Act (1974), and the Federal Insecticide, Fungicide, and Rodenticide Act, as amended in 1988. In the United States in 1996, nearly $10 billion was spent on water and wastewater treatment alone. International cooperation is being promoted by the Inter-Governmental Maritime Consultive Organization (IMCO), a UN agency. Limitation of ocean dumping was proposed at the 80-nation London Conference of 1972, and in the same year 12 European nations meeting in Oslo adopted rules to regulate dumping in the North Atlantic. An international ban on ocean dumping in 1988 set further restrictions.
|Law Encyclopedia: Water Pollution|
This entry contains information applicable to United States law only.
Without healthy water for drinking, cooking, fishing, and farming, the human race would perish. Clean water is also necessary for recreational interests such as swimming, boating, and water skiing. Yet, when Congress began assessing national water quality during the early 1970s, it found that much of the country’s groundwater and surface water was contaminated or severely compromised. Studies revealed that the nation’s three primary sources of water pollution — industry, agriculture, and municipalities — had been regularly discharging harmful materials into water supplies throughout the country over a number of years.
These harmful materials included organic wastes, sediments, minerals, nutrients, thermal pollutants, toxic chemicals, and other hazardous substances. Organic wastes are produced by animals and humans, and include such things as fecal matter, crop debris, yard clippings, food wastes, rubber, plastic, wood, and disposable diapers. Such wastes require oxygen to decompose. When they are dumped into streams and lakes and begin to break down, they can deprive aquatic life of the oxygen it needs to survive.
Sediments may be deposited into lakes and streams through soil erosion caused by the clearing, excavating, grading, transporting, and filling of land. Minerals, such as iron, copper, chromium, platinum, nickel, zinc, and tin, can be discharged into streams and lakes as a result of various mining activities. Excessive levels of sediments and minerals in water can inhibit the penetration of sunlight, which reduces the production of photosynthetic organisms.
Nutrients, like phosphorus and nitrogen, support the growth of algae and other plants forming the lower levels of the food chain. However, excessive levels of nutrients from sources such as fertilizer can cause eutrophication, which is the overgrowth of aquatic vegetation. This overgrowth clouds the water and smothers some plants. Over time, excessive nutrient levels can accelerate the natural process by which bodies of water evolve into dry land.
Thermal pollution results from the release of heated water into lakes and streams. Most thermal pollution is generated by power plant cooling systems. Power plants use water to cool their reactors and turbines, and discharge it into lakes and tributaries after it has become heated. Higher water temperatures accelerate biological and chemical processes in rivers and streams, reducing the water’s ability to retain dissolved oxygen. This can hasten the growth of algae and disrupt the reproduction of fish.
Toxic chemicals and other hazardous materials present the most imminent threat to water quality. The Environmental Protection Agency (EPA) has identified 403 highly toxic chemicals, which are produced by 577 U.S. companies, manufactured in twelve thousand plants, and stored in four-hundred thousand locations across the country. Some chemical plants incinerate toxic wastes, which produces dangerous by-products like furans and chlorinated dioxins, two of the most deadly carcinogens known to the human race. Other hazardous materials are produced or stored by households (motor oil, antifreeze, paints, and pesticides), dry cleaners (chlorinated solvents), farms (insecticides, fungicides, rodenticides, and herbicides), and gas stations and airports (fuel).
Water pollution regulation consists of a labyrinth of state and federal statutes, administrative rules, and common-law principles.
Federal statutory regulation of water pollution has been governed primarily by three pieces of legislation: the Refuse Act, the Federal Water Pollution Control Act, and the Clean Water Act. The Rivers and Harbors Appropriations Act of 1899, 33 U.S.C.A. § 401 et seq., commonly known as the Refuse Act, was the first major piece of federal legislation regulating water pollution. The Refuse Act set effluent standards for the discharge of pollutants into bodies of water. An effluent standard limits the amount of pollutant that can be released from a specific point or source, such as a smokestack or sewage pipe. The Refuse Act flatly prohibited pollution discharged from ship and shore installations.
The Refuse Act was followed by the Federal Water Pollution Control Act of 1948 (FWPCA), 33 U.S.C.A. § 1251 et seq. Instead of focusing on sources of pollution through effluent standards, the FWPCA created water quality standards, which prescribed the levels of pollutants permitted in a given body of water. Where the Refuse Act concentrated on deterring specific types of polluters, the FWPCA concentrated on reducing specific types of pollution.
Since 1972, federal regulation of water pollution has been primarily governed by the Clean Water Act (CWA), which overhauled FWCPA. The CWA forbids any person to discharge pollutants into U.S. waters unless the discharge conforms with certain provisions of the act. Among those provisions are several that call upon the EPA to promulgate effluent standards for particular categories of water polluters.
To implement these standards, the CWA requires each polluter to obtain a discharge permit issued by the EPA through the National Pollutant Discharge Elimination System (NPDES). Although the EPA closely monitors water pollution dischargers through the NPDES, primary responsibility for enforcement of the CWA rests with the states. Most states have also drafted permit systems similar to the NPDES. These systems are designed to protect local supplies of groundwater, surface water, and drinking water. Persons who violate either the federal or state permit system face civil fines, criminal penalties, and suspension of their discharge privileges.
The CWA also relies on modern technology to curb water pollution. It requires many polluters to implement the best practicable control technology, the best available technology economically achievable, or the best practicable waste treatment technology. The development of such technology for nontoxic polluters is based on a cost-benefit analysis in which the feasibility and expense of the technology is balanced against the expected benefits to the environment.
The CWA was amended in 1977 to address the nation’s increasing concern about toxic pollutants. Pursuant to the 1977 amendments, the EPA increased the number of pollutants it deemed toxic from nine to sixty-five, and set effluent limitations for the twenty-one industries that discharge them. These limitations are based on measures of the danger these pollutants pose to the public health rather than on cost-benefit analyses.
Many states have enacted their own water pollution legislation regulating the discharge of toxic and other pollutants into their streams and lakes.
The mining industry presents persistent water pollution problems for state and federal governments. It has polluted over a thousand miles of streams in Appalachia with acid drainage. In response, the affected state governments now require strip miners to obtain licenses before commencing activity. Many states also require miners to post bonds in an amount sufficient to repair potential damage to surrounding lakes and streams. Similarly, the federal government, under the Mineral Leasing Act, 30 U.S.C.A. § 201 et seq., requires each mining applicant to “submit a plan of construction, operation and rehabilitation” for the affected area, that takes into account the need for “restoration, revegetation and curtailment of erosion.”
The commercial timber industry also presents persistent water pollution problems. Tree harvesting, yarding (the collection of felled trees), and road building can all deposit soil sediments into watercourses, thereby reducing the water quality for aquatic life. State governments have offered similar responses to these problems. For instance, clear-cutting (the removal of substantially all the trees from a given area) has been prohibited by most states. Other states have created buffer zones around particularly vulnerable watercourses, and banned unusually harmful activities in certain areas. Enforcement of these water pollution measures has been frustrated by vaguely worded legislation and a scarcity of inspectors in several states.
State and federal water pollution statutes provide one avenue of legal recourse for those harmed by water pollution. The common-law doctrines of nuisance, trespass, negligence, strict liability, and riparian ownership provide alternative remedies.
Nuisances can be public or private. Private nuisances interfere with the rights and interests of private citizens, whereas public nuisances interfere with the common rights and interests of the people at large. Both types of nuisance must result from the “unreasonable” activities of a polluter, and inflict “substantial” harm on neighboring landowners. An injury that is minor or inconsequential will not result in liability under common-law nuisance. For example, dumping trace amounts of fertilizer into a stream abutting neighboring property will not amount to a public or private nuisance.
The oil and agricultural industries are frequently involved in state nuisance actions. Oil companies often run afoul of nuisance principles for improperly storing, transporting, and disposing of hazardous materials. Farmers represent a unique class of persons who fall prey to water pollution nuisances almost as often as they create them. Their abundant use of fungicides, herbicides, insecticides, and rodenticides makes them frequent creators of nuisances, and their use of streams, rivers, and groundwater for irrigation systems makes them frequent victims.
Nuisance actions deal primarily with continuing or repetitive injuries. Trespass actions provide relief even when an injury results from a single event. A polluter who spills oil, dumps chemicals, or otherwise contaminates a neighboring water supply on one occasion might avoid liability under nuisance law but not under the law of trespass. Trespass does not require proof of a substantial injury. However, only nominal damages will be awarded to a landowner whose water supply suffers little harm from the trespass of a polluter.
Trespass requires proof that a polluter intentionally or knowingly contaminated a particular course of water. Yet, water contamination often results from unintentional behavior, such as industrial accidents. In such instances, the polluter may be liable under common-law principles of negligence. Negligence occurs when a polluter fails to exercise the degree of care that would be reasonable under the circumstances. Thus, a landowner whose water supply was inadvertently contaminated might bring a successful lawsuit against the polluter for common-law negligence where a lawsuit for nuisance or trespass would fail.
Even when a polluter exercises the utmost diligence to prevent water contamination, an injured landowner may still have recourse under the doctrine of strict liability. Under this doctrine, polluters who engage in “abnormally dangerous” activities are held responsible for any water contamination that results. Courts consider six factors when determining whether a particular activity is abnormally dangerous: the probability that the activity will cause harm to another, the likelihood that the harm will be great, the ability to eliminate the risk by exercising reasonable care, the extent to which the activity is uncommon or unusual, the activity’s appropriateness for a particular location, and the activity’s value or danger to the community.
The doctrine of strict liability arose out of a national conflict between competing values during the industrial revolution. This conflict pitted those who believed it was necessary to create an environment that promoted commerce against those who believed it was necessary to preserve a healthy and clean environment. For many years, courts were reluctant to impose strict liability on U.S. businesses, out of concern over retarding industrial growth.
Since the early 1970s, courts have placed greater emphasis on preserving a healthy and clean environment. In Cities Service Co. v. State, 312 So. 2d 799 (Fla. App. 1975), the court explained that “though many hazardous activities … are socially desirable, it now seems reasonable that they pay their own way.” Cities Service involved a situation in which a dam burst during a phosphate mining operation, releasing a billion gallons of phosphate slime into adjacent waterways, where fish and other aquatic life were killed. The court concluded that this mining activity was abnormally dangerous.
Some activities inherently create abnormally dangerous risks to abutting waterways. In such cases, courts do not employ a balancing test to determine whether an activity is abnormally dangerous. Instead, they consider these activities to be dangerous in and of themselves. The transportation and storage of high explosives and the operation of oil and gas wells are activities courts have held to create inherent risks of abnormally dangerous proportions.
The doctrine of riparian ownership forms the final prong of common-law recovery. A riparian proprietor is the owner of land abutting a stream of water, and has the right to divert the water for any useful purpose. Some courts define the term useful purpose broadly to include almost any purpose whatsoever, whereas other courts define it more narrowly to include only purposes that are reasonable or profitable.
In any event, downstream riparian proprietors are often placed at a disadvantage because the law protects upstream owners’ initial use of the water. For example, an upstream proprietor may construct a dam to appropriate a reasonable amount of water without compensating a downstream proprietor. However, cases involving thermal pollution provide an exception to this rule. For example, downstream owners who use river water to make ice can seek injunctive relief to prevent upstream owners from engaging in any activities that raise the water temperature by even one degree Fahrenheit.
|Science Dictionary: water pollution|
The addition of harmful chemicals to natural water. Sources of water pollution in the United States include industrial waste, run-off from fields treated with chemical fertilizers, and run-off from areas that have been mined.
|Wikipedia: Water pollution|
Water pollution is the contamination of water bodies such as lakes, rivers, oceans, and groundwater caused by human activities, which can be harmful to organisms and plants that live in these water bodies.
Water is typically referred to as polluted when it is impaired by anthropogenic contaminants and either does not support a human use, like serving as drinking water, or undergoes a marked shift in its ability to support its constituent biotic communities, such as fish. Natural phenomena such as volcanoes, algae blooms, storms, and earthquakes also cause major changes in water quality and the ecological status of water. Water pollution has many causes and characteristics.
Water pollution categories
Surface water and groundwater have often been studied and managed as separate resources, although they are interrelated. Sources of surface water pollution are generally grouped into two categories based on their origin.
Point source pollution
Point source pollution refers to contaminants that enter a waterway through a discrete conveyance, such as a pipe or ditch. Examples of sources in this category include discharges from a sewage treatment plant or a factory, or a leaking underground storage tank. The U.S. Clean Water Act (CWA) defines point source for regulatory enforcement purposes.
Non-point source pollution
Non-point source (NPS) pollution refers to diffuse contamination that does not originate from a single discrete source. NPS pollution is often a cumulative effect of small amounts of contaminants gathered from a large area. Nutrient runoff in stormwater from “sheet flow” over an agricultural field, or metals and hydrocarbons from an area with highly impervious surfaces and vehicular traffic are sometimes cited as examples of NPS pollution.
The primary focus of legislation and efforts to curb water pollution for the past several decades was first aimed at point sources. As point sources have been effectively regulated, greater attention has been placed on NPS contributions, especially in rapidly urbanizing or developing areas.
Interactions between groundwater and surface water are complex. Consequently, groundwater pollution, sometimes referred to as groundwater contamination, is not as easily classified as surface water pollution. By its very nature, groundwater aquifers are susceptible to contamination from sources that may not directly affect surface water bodies, and the distinction of point vs. nonpoint source may be irrelevant. A spill of a chemical contaminant on soil, located away from a surface water body, may not necessarily create point source or non-point source pollution, but nonetheless may contaminate the aquifer below. Analysis of groundwater contamination may focus on soil characteristics and hydrology, as well as the nature of the contaminant itself.
Materials and phenomena contributing to water pollution
The specific contaminants leading to pollution in water include a wide spectrum of chemicals, pathogens, and physical or sensory changes such as elevated temperature and discoloration. While many of the chemicals and substances that are regulated may be naturally occurring (iron, manganese, etc.) the concentration is often the key in determining what is a natural component of water, and what is a contaminant.
Oxygen-depleting substances may be natural materials, such as plant matter (e.g. leaves and grass) as well as man-made chemicals. Other natural and anthropogenic substances may cause turbidity (cloudiness) which blocks light and disrupts plant growth, and clogs the gills of some fish species.
Many of the chemical substances are toxic. Pathogens can produce waterborne diseases in either human or animal hosts. Alteration of water’s physical chemistry include acidity, electrical conductivity, temperature, and eutrophication. Eutrophication is the fertilization of surface water by nutrients that were previously scarce. Water pollution is a major problem in the global context. It has been suggested that it is the leading worldwide cause of deaths and diseases, and that it accounts for the deaths of more than 14,000 people daily.
Chemical and other contaminants
Organic water pollutants include:
- Insecticides and herbicides, a huge range of organohalides and other chemical compounds
- Bacteria from sewage or livestock operations
- Food processing waste, which can oxygen-demanding substances, fats and grease
- Tree and brush debris from logging operations
- VOCs (volatile organic compounds), such as industrial solvents, from improper storage
- DNAPLs (dense non-aqueous phase liquids), such as chlorinated solvents, which may fall at the bottom of reservoirs, since they don’t mix well with water and are denser
- Petroleum hydrocarbons, including fuels (gasoline, diesel fuel, jet fuels, and fuel oil) and lubricants (motor oil). (Note: VOCs include gasoline-range hydrocarbons.)
- Various chemical compounds found in personal hygiene and cosmetic products
- Disinfection by-products found in chemically disinfected drinking water
Inorganic water pollutants include:
- Ammonia from food processing waste
- Heavy metals including acid mine drainage
- Acidity caused by industrial discharges (especially sulfur dioxide from power plants)
- Pre-production industrial raw resin pellets, an industrial pollutant
- Chemical waste as industrial by-products
- Fertilizers, in runoff from agriculture including nitrates and phosphates
- Silt (sediment) in surface runoff from construction sites, logging, slash and burn practices or land clearing sites
Macroscopic pollution–large visible items polluting the water–may be termed “floatables” in an urban stormwater context, or marine debris when found on the open seas, and can include such items as:
- trash items (e.g. paper, plastic, or food waste) discarded by people on the ground, and that are washed by rainfall into storm drains and eventually discharged into surface waters
- Nurdles, small ubiquitous waterborne plastic pellets
- Shipwrecks, large derelict ships
Transport and chemical reactions of water pollutants
Most water pollutants are eventually carried by rivers into the oceans. In some areas of the world the influence can be traced hundred miles from the mouth by studies using hydrology transport models. Advanced computer models such as SWMM or the DSSAM Model have been used in many locations worldwide to examine the fate of pollutants in aquatic systems. Indicator filter feeding species such as copepods have also been used to study pollutant fates in the New York Bight, for example. The highest toxin loads are not directly at the mouth of the Hudson River, but 100 kilometers south, since several days are required for incorporation into planktonic tissue. The Hudson discharge flows south along the coast due to coriolis force. Further south then are areas of oxygen depletion, caused by chemicals using up oxygen and by algae blooms, caused by excess nutrients from algal cell death and decomposition. Fish and shellfish kills have been reported, because toxins climb the food chain after small fish consume copepods, then large fish eat smaller fish, etc. Each successive step up the food chain causes a stepwise concentration of pollutants such as heavy metals (e.g. mercury) and persistent organic pollutants such as DDT. This is known as biomagnification, which is occasionally used interchangeably with bioaccumulation.
Large gyres (vortexes) in the oceans trap floating plastic debris. The North Pacific Gyre for example has collected the so-called “Great Pacific Garbage Patch” that is now estimated at 100 times the size of Texas. Many of these long-lasting pieces wind up in the stomachs of marine birds and animals. This results in obstruction of digestive pathways which leads to reduced appetite or even starvation.
Many chemicals undergo reactive decay or chemically change especially over long periods of time in groundwater reservoirs. A noteworthy class of such chemicals is the chlorinated hydrocarbons such as trichloroethylene (used in industrial metal degreasing and electronics manufacturing) and tetrachloroethylene used in the dry cleaning industry (note latest advances in liquid carbon dioxide in dry cleaning that avoids all use of chemicals). Both of these chemicals, which are carcinogens themselves, undergo partial decomposition reactions, leading to new hazardous chemicals (including dichloroethylene and vinyl chloride).
Groundwater pollution is much more difficult to abate than surface pollution because groundwater can move great distances through unseen aquifers. Non-porous aquifers such as clays partially purify water of bacteria by simple filtration (adsorption and absorption), dilution, and, in some cases, chemical reactions and biological activity: however, in some cases, the pollutants merely transform to soil contaminants. Groundwater that moves through cracks and caverns is not filtered and can be transported as easily as surface water. In fact, this can be aggravated by the human tendency to use natural sinkholes as dumps in areas of Karst topography.
There are a variety of secondary effects stemming not from the original pollutant, but a derivative condition. Some of these secondary impacts are:
- Silt-bearing surface runoff from can inhibit the penetration of sunlight through the water column, hampering photosynthesis in aquatic plants.
- Thermal pollution can induce fish kills and invasion by new thermophilic species. This can cause further problems to existing wildlife.
Measurement of water pollution
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Water pollution may be analyzed through several broad categories of methods: physical, chemical and biological. Each method involves collection of samples, followed by specialized analytical tests. Government agencies and research organizations have published standardized, validated analytical test methods to facilitate the comparability of results from disparate testing events.
- See also: Water quality
Sampling of water for physical or chemical testing can be done by several methods, depending on the accuracy needed and the characteristics of the contaminant. Many contamination events are sharply restricted in time, most commonly in association with rain events. For this reason “grab” samples are often inadequate for fully quantifying contaminant levels. Scientists gathering this type of data often employ auto-sampler devices that pump increments of water at either time or discharge intervals.
Sampling for biological testing involves collection of plants and/or animals.
Common physical tests of water include temperature, solids concentration (e.g. total suspended solids, and turbidity.
Water samples may be examined using the principles of analytical chemistry. Many published test methods are available for both organic and inorganic compounds. Frequently-used methods include biochemical oxygen demand (BOD), chemical oxygen demand (COD), nutrients (nitrate and phosphorus compounds), metals (including copper, zinc, cadmium. lead and mercury), oil and grease, total petroleum hydrocarbons (TPH), and pesticides.
In the UK there are common law rights (civil rights) to protect the passage of water across land unfettered in either quality of quantity. Criminal laws dating back to the 16th century exercised some control over water pollution but it was not until the River (Prevention of pollution) Acts 1951 – 1961 were enacted that any systematic control over water pollution was established. These laws were strengthened and extended in the Control of Pollution Act 1984 which has since been updated and modified by a series of further acts. It is a criminal offense to either pollute a lake, river, groundwater or the sea or to discharge any liquid into such water bodies without proper authority. In England and Wales such permission can only be issued by the Environment Agency and in Scotland by SEPA.
In the USA, concern over water pollution resulted in the enactment of state anti-pollution laws in the latter half of the 19th century, and federal legislation enacted in 1899. The Refuse Act of the federal Rivers and Harbors Act of 1899 prohibits the disposal of any refuse matter from into either the nation’s navigable rivers, lakes, streams, and other navigable bodies of water, or any tributary to such waters, unless one has first obtained a permit. The Water Pollution Control Act, passed in 1948, gave authority to the Surgeon General to reduce water pollution. However, this law did not lead to major reductions in pollution.
Growing public awareness and concern for controlling water pollution led Congress to carry out a major re-write of water pollution law in 1972. The Federal Water Pollution Control Act Amendments of 1972, commonly known as the Clean Water Act (CWA), established the basic mechanisms for controlling point source pollution. The law mandated the United States Environmental Protection Agency (EPA) to publish and enforce wastewater standards for industry and municipal sewage treatment plants. The Act also continued requirements that EPA and states issue water quality standards for surface water bodies. Congress included authorization in the Act for major public financing to build municipal sewage treatment plants. The 1972 CWA, however, did not require similar regulatory standards for non-point sources.
In 1987, Congress expanded the coverage of the CWA with enactment of the Water Quality Act. These amendments defined both municipal and industrial stormwater discharges as point sources and required these facilities to obtain discharge permits. The 1987 law also re-organized the public financing of municipal treatment projects and created a non-point source demonstration grant program. Further amplification of the CWA included the enactment of the Great Lakes Legacy Act of 2002.
- ^ a b United States Geological Survey. Denver, CO. “Ground Water and Surface Water: A Single Resource.” USGS Circular 1139. 1998.
- ^ Clean Water Act, section 502(14), (14).
- ^ However, the CWA defines urban surface runoff discharges–i.e. discharges from municipal storm sewers–as point sources.
- ^ Pink, Daniel H. (April 19, 2006). “Investing in Tomorrow’s Liquid Gold“, Yahoo.
- ^ a b West, Larry (March 26, 2006). “World Water Day: A Billion People Worldwide Lack Safe Drinking Water“, About.
- ^ For example, see Clescerl, Leonore S.(Editor), Greenberg, Arnold E.(Editor), Eaton, Andrew D. (Editor). Standard Methods for the Examination of Water and Wastewater (20th ed.) American Public Health Association, Washington, DC. ISBN 0-87553-235-7. This publication is also available on CD-ROM and online by subscription.
- ^ Pub.L. 92-500, October 18, 1972. et seq.
- ^ Pub.L. 100-4, February 4, 1987.
- ^ Pub.L. 107-303, November 27, 2002
- Aquatic toxicology
- Cultural eutrophication
- Industrial wastewater treatment
- Oil spills
- Marine debris
- Marine pollution
- Paper pollution
- Trophic state index
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- Report Pollution from Ships
- www.black-tides.com – An educational website for young people on oil spills
- Coastal Pollution Information from the Coastal Ocean Institute, Woods Hole Oceanographic Institution
- U.S. Environmental Protection Agency Clean Water Act
- EPA Causal Analysis/Diagnosis Decision Information System (CADDIS) – Stressor Identification
- Congressional Research Service (CRS) Reports regarding Water Pollution
- Natural Resources Defense Council (NRDC): overviews, news and reports on water pollution
- Troubled Waters: Episode and web site from National Geographic/PBS’s “Strange Days on Planet Earth”
- Water Quality in South Australia
- Original case-study of the sustained criminal pollution of Long Lake, a tributary of the Mississippi, by Chemetco
- Threatened Waters: Turning the Tide on Pesticide Contamination, by Beyond Pesticides
- American Water Resources Association
- Filterra: Bioretention as a method to manage stormwater pollution and urban runoff
- Water shortage in the future and its consequences (Slide Show)
- Bibliography on Water Resources and International Law Peace Palace Library
- DWEL Digital Water Education Library, see its entry on the NSDL 
- Portal for soil and water management in Europe Independent information gateway originally funded by the European Commission for topics related to soil and water, including contaminated land, soil and water management.