Water pollution refers to the presence of compounds that decrease the quality of fresh or marine water. This is a broad definition that takes into account a variety of water sources including lakes, streams, rivers, oceans, and groundwater. As well, the sources of water pollution can be natural, such as animal waste, or more commonly, due to human activity.
There are many causes of human-mediated water pollution, including runoff of pesticides, herbicides, and feces from agricultural land; runoff of gasoline and other chemicals from concrete in urban settings; and household chemicals discarded by flushing down the toilet (such as medicines or household cleaners).
Water pollution is a major global concern. In developing countries, waterborne diseases such as cholera, typhoid fever, and hepatitis A are among the leading causes of illness and death, killing over 3.4 million people every year (including 4,000 children every day), according to the World Health Organization (WHO).
In the environment, water pollution can alter or destroy a watercourse directly by the addition of the pollutants, and indirectly when the pollutant can be used as food source by microorganisms, whose explosive increase in growth and total numbers depletes the water of oxygen.
Historical Background and Scientific Foundations
As humans began to shift from a nomadic way of living to settlements, the communities were virtually always located near water. The importance of clean water to health was recognized thousands of years ago, even if the reason was not understood. For example, in ancient Rome, the Tiber River became so polluted with the direct discharge of human sewage that separate channels were built for drinking water. Throughout the next two millennia, waterborne illness outbreaks occurred; from the descriptions provided, it is likely that many were cholera and typhoid. Even today, cholera remains a problem in areas of the world that do not have access to clean water.
It was not until the 1850s that the connection was made between water contaminated with human feces and disease. Then, during a cholera outbreak in London, physician John Snow (1813–1858) deduced that fecal-contaminated water from a particular well was implicated in the illness. Stopping the use of the well stopped the spread of the disease.
Similarly, in the United States, rivers were used to dispose of human waste for centuries. With the growth of industries, waters also became the disposal system for industrial waste, a practice that continued into the twentieth century. An example is the Cuyahoga River in Cleveland, Ohio, which periodically caught fire from the 1930s into the 1970s due to oil and other flammable industrial waste discharged into the water. Finally, a fire in 1969 that was immortalized in a song (“Burn On”) by American recording artist Randy Newman drew attention to the deplorable condition of the Cuyahoga and other American waterways, which spurred passage of the Clean Water Act in 1972. The legislation banned the release of pollutants in waterways used by craft, although it has subsequently been criticized for a lack of standards of toxicity and difficulty in identifying pollution that does not come from a single source (non-point source pollution).
In the decades of prosperity following World War II (1939–1945), many chemicals were synthesized and commercialized. Antibiotics and DDT, for example, were spectacularly successful at stopping the spread of a variety of diseases (at least until resistance developed). At the same time, these and other compounds were finding
WORDS TO KNOW
AQUIFER: Rock, soil, or sand underground formation that is able to hold and/or transmit water.
COLIFORMS: Bacteria that live in the intestinal tract of warm-blooded animals. The presence of coliforms in water indicates fecal pollution.
DISINFECTION BY-PRODUCT: A compound created by the interaction of a disinfectant chemical and organic compounds in the water.
EUTROPHICATION: The process whereby a body of water becomes rich in dissolved nutrients through natural or man-made processes. This often results in a deficiency of dissolved oxygen, producing an environment that favors plant over animal life.
GROUNDWATER: Fresh water that is present in an underground location.
HYDROLOGY: The study of the distribution, movement, and physical-chemical properties of water in Earth’s atmosphere, surface, and near-surface crust.
RUNOFF: Water that falls as precipitation and then runs over the surface of the land rather than sinking into the ground.
Preventing Waterborne Disease
Microorganisms are an important source of water pollution. Some microorganisms that are of concern live in the intestinal tract of warm-blooded animals, including humans. Examples of disease-causing (pathogenic) bacteria are Salmonella, Shigella, Vibrio, and Escherichia. With the latter, Escherichia coli 0157:H7 is particularly dangerous. Contamination of drinking water with 0157:H7 can cause severe illness, permanent kidney damage, and even death. In an infamous example, contamination of the municipal water supply of Walkerton, Ontario, Canada, in the summer of 2000 because of runoff from adjacent cattle farms sickened over 2,000 people and killed 7.
The intestinal tract of warm-blooded animals also harbors pathogenic (disease-causing) viruses that can contaminate water, in particular rotavirus, enterovirus, norovirus, and coxsackievirus. A number of protozoan microorganisms can also affect water quality. The two most prominent protozoans are Giardia and Cryptosporidium, which normally live in the intestinal tracts of wild animals such as beaver and deer.
Municipal drinking water is usually treated with disinfectants in order to minimize the risk of microbial contamination. One common disinfectant is chlorine. Other treatments that kill bacteria include the use of a gaseous form of ozone (a compound containing three oxygen atoms, which is also present in Earth’s atmosphere), and exposure of shallow water to ultraviolet light. The ultraviolet radiation breaks apart the bacterial genetic material so much so that it cannot be repaired, and the microbe dies. Filters can also be used in water treatment; they contain openings of some filters that are so tiny that even viruses that are 10 nanometers in diameter are blocked from passing through (a nanometer is one-billionth of a meter).
Water polluted with protozoans can be more difficult to treat, as both Giardia and Cryptosporidium form chlorine-resistant structure cysts that can pass through the water treatment filters. In 1993, the contamination of the water supply of Milwaukee, Wisconsin, sickened over 400,000 people and at least 47 people died.
Non-point Source Pollution
Non-point source pollution enters water from many different sites, rather than from a single site. Examples of non-point source pollution are acid rain and runoff of polluted water from the urban and rural land. The nitrogen and phosphorus in fertilizers can be a source of food to microorganisms such as algae. Their resulting rapid growth and increase in numbers can deplete the oxygen in the water. In some areas of North America, huge factory farms contain tens of thousands of poultry or pigs. The waste material and huge amounts of water used in the farm operation are typically stored in large lagoons. Rupture of a lagoon wall can release the toxic water into nearby watercourses or into the groundwater.
Because of the many possible sites of non-point source pollution, tracking down the origin of the water pollution can be difficult. In contrast, an example of a point source is polluted material flowing from one factory into a river. This type of pollution can be much easier to detect and to stop.
According to the U.S. Environmental Protection Agency (EPA), as of 2008, about 40% of all the U.S. freshwater sources that have been mapped have been so affected by non-point source pollution that they are not safe for swimming or fishing.
There are a variety of organic (carbon-containing) water pollutants in addition to microorganisms. There are many types of chemicals that kill insects (insecticides) and weeds (herbicides). Runoff of moisture from agricultural land or urban lawns can carry these chemicals into streams, rivers, and lakes. Similarly, leakage of industrial chemicals, oil, and gasoline can occur both above the ground and from underground storage tanks. The latter can be especially serious since it may escape detection for a long time, and the pollutant can move outward from the source, even into groundwater.
The treatment of water can generate disinfection byproducts such as trihalomethanes, when chlorine reacts with organic matter. This tends to occur with surface waters, as more organic material can be present in the water. Trihalomethanes are considered a pollutant since they affect the smell and taste of the drinking water.
A more recent concern are the various drugs that people discard by flushing them down the toilet or the ones that can end up in landfills. With the development of technologies that can detect very low levels of drugs (parts per billion, equivalent to a drop of water in an Olympic sized swimming pool), the presence of (as a few examples) cosmetics, detergents, toiletries, painkillers, tranquilizers, anti-depressants, antibiotics, birth control pills, estrogen replacement therapy drugs, chemotherapy drugs, and epilepsy treatment drugs have all been detected in the environment. Some pharmaceuticals and drugs, including caffeine and acetaminophen (Tylenol), have also been detected in drinking water.
Although concentrations of most of these chemicals are not a concern in the short term, it is unknown if longer-term exposure is harmful. In 1999–2000, the most recent survey of the U.S. Geological Survey tested 139 streams from 30 states for 95 contaminants. Some 75% contained two or more of these contaminants, with 13% of the streams containing 20 or more.
Inorganic water pollutants include heavy metals, acidic materials, nitrogen and phosphorus that are part of fertilizers, and silt from construction sites and clear-cut lands that is washed into watercourses.
A well-known inorganic water pollutant is Dichloro-Diphenyl-Trichloroethane (DDT). DDT exposure causes adverse effects in humans, animals, and birds in the short-term and more chronically. Possible longer-term effects include difficulties in reproduction, altered development of a fetus, and both liver and lung cancer. Prior to the ban on DDT use in the United States, bald eagle populations had declined to levels that threatened the species due to the accumulation of the pesticide in the bird’s tissue, which caused production of eggs with thinner, more fragile shells. As the compound has gradually declined in the environment in the decades following the ban, bald eagle populations have rebounded.
One major reason for the chronic effects of DDT is bioaccumulation, the accumulation of a compound in tissues of one species that is passed on to species higher in the food chain. As a result, creatures including the bald eagle ingest a much higher level of the toxin than they otherwise would and store the poison in fatty tissues, where it can persist.
The structure of DDT also makes it difficult to degrade. It can persist in water for months. Degradation is not a solution, since two breakdown products also persist in the environment and can cause adverse effects.
Compounds that can leak out of landfills can also degrade slowly, as do petroleum and petroleum-based products; polychlorinated biphenyls (PCBs); dioxins and polyaromatic hydrocarbons (PAHs); metals such as lead, mercury, and cadmium; and some kinds of radioisotopes. As an example, one of the considerations in selecting Yucca Mountain in Nevada as an underground garbage site for radioactive waste was the geology of the volcanic rock, which lacked cracks that could allow the waste to move from the site of storage in the event of a leak, and the fact that groundwater was very far beneath the storage area. Thus, the likelihood of radioactive contamination of the groundwater would be remote. This is good, since radioisotopes can have a half-life (the time for half the radioactivity to be degraded) of thousands of years, which would irreversibly contaminate water. Although the concern over water pollution may have been met, other concerns have pushed back the planned 1998 opening to 2017.
Water pollution due to chemicals is an inevitable consequence of modern society. Chemicals are used for a variety of everyday activities; only a very few examples are dishwashing, house cleaning, lawn care, and interior and exterior painting. Environment Canada estimates that 100,000 chemicals are commonly used.
Some such as pesticides, PCBs (which were used as a coolants in electrical transformers), and polychlorinated phenols (PCPs; which are present in wood preservatives) are toxic even when present in very low amounts. While PCBs were banned in the 1970s because of their environmental toxicity, they can still be found in older transformers. These compounds are designed and used because of their toxicity and long-lasting property—the same properties that make them so detrimental to the environment.
Acid rain is a serious form of water pollution, particularly in the northeastern United States. The term comes from the presence of nitric and sulfuric acids in the atmosphere close to the surface. Acid rain can be produced naturally, but the majority is generated by human activities, mainly from electricity generation that relies on the burning of fossil fuels such as coal. The burning releases sulfur dioxide and nitrogen oxides, which react with atmospheric water, oxygen, and other compounds to form a mild solution containing the nitric and sulfuric acids. The small droplets can stay suspended in the air and can be blown for hundreds of miles. As time goes on, the continued deposition of the droplets in water sources makes the water more acidic, which can kill vegetation and fish. As species lower in the food chain are affected, the entire ecosystem of a lake can be affected. In areas where acid rain is especially pronounced, the result can be lakes that are devoid of life. A lake that has been affected by acid rain can be sparkling clear in appearance. This beauty is deceptive, since the reason the water is so clear is that there is no microscopic of other life present.
In contrast, the phenomenon of eutrophication occurs because of the opposite reason; the presence of too much life. The overgrowth of the many organisms depletes the oxygen from the water. Although eutrophication is a natural process, it is greatly accelerated by pollution with compounds such as nitrogen and phosphorus, which are components of fertilizer. Drainage of fertilizer from surrounding land into a waterway boosts the amount of nutrients in the water, which can cause the explosive growth of microorganisms. The oxygen-starved water becomes inhospitable for fish. In turn, the decay of the dead fish uses up even more oxygen.
Impacts and Issues
One recent example of the effects of eutrophication and of the recovery that is possible even in severely polluted water is Lake Erie. In the 1960s, the addition of nitrogen and phosphorus to Lake Erie, the shallowest of the five Great Lakes, had depleted the oxygen to such an extent that massive deaths of fish were occurring. In 1972, legislation banning the use of phosphate in laundry detergent was passed. This reduced the amount of phosphorus entering Lake Erie by about 90%. The quality of the water recovered. In 2008, Lake Erie supports an abundance of life.
Groundwater pollution represents an even more serious threat to human health, because the pollutant can remain in the water; water contaminated with a radioactive substance, for example, can be unusable for
IN CONTEXT: WATER POLLUTION IMPACTS ON MICROORGANISMS
There is a microbiological aspect of water pollution that experts fear reduces our ability to treat some bacterial infections: the presence in water of agents used to treat bacteria in other environments. For example, in the household a number of disinfectant compounds are routinely employed in the cleaning of household surfaces. In the hospital, the use of antibiotics to kill bacteria is an everyday occurrence. Such materials have been detected in water both before and after municipal wastewater treatment. The health effect of these compounds is not known at the present time. However, by analogy with other systems, the low concentration of such compounds might provide selective pressure for the development of resistant bacterial populations.
thousands of years. In the United States, about half the population relies on groundwater as a drinking water source, for industrial purposes, or for crop irrigation.
Pollution of groundwater is not rare. For example, the EPA has records of over 400,000 cases of petroleum-based fuel spills from underground storage tanks. Although detection and remediation of groundwater pollution is a priority in the United States as mandated by the Resource Conservation and Recovery Act (RCRA) and the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA, which is also known as the Superfund), it is often a less important priority in developing countries where resources are limited. Developing countries also bear the brunt of waterborne diseases, due to the presence of pathogenic bacteria and viruses in water.
Recent studies indicate that global warming might create a more favorable environment for V cholerae, the bacteria that causes cholera, and increase the incidence of the disease in vulnerable areas. A majority of cholera deaths occur in children under five years of age. Aside from the human tragedy of this loss, the effect on the economy is felt for decades. The World Health Organization has estimated that, in the poorest of developing nations, every dollar spent to remedy water pollution and inadequate sanitation would produce an economic return of $3 to $34.
The United Nations has set a goal of reducing by half the number of people who do not have access to safe drinking water and adequate sanitation by the year 2015. This goal will require the participation of developed countries and comes at a time when the changing global climate is beginning to affect the availability of water, and the prevalence of waterborne microbial diseases such as malaria and cholera.
Primary Source Connection
The Water Quality Act of 1965 and the amendments that became law in 1977 represent two of several initiatives by the U.S. government to protect and ensure the quality of surface and ground waters.
Legislative concern over water quality began in 1948, with the passage of the Water Pollution Control Act. The act was essentially an adoption of principles to be followed in the pursuit of water quality. It was the Water Quality Act of 1965 that put some legislative teeth to these principles.
The 1965 legislation directed the states to develop water-quality standards. A federally directed initiative was deemed necessary since many watersheds and waterways crossed state boundaries. By the early 1970s, water quality standards had been developed and enacted by all the states. Since then, revisions have occurred to reflect changing scientific information and new testing procedures.
THE WATER QUALITY ACT OF 1965
To amend the Federal Water Pollution Control Act to establish a Federal Water Pollution Control Administration, to provide grants for research and development, to increase grants for construction of sewage treatment works, to require establishment of water quality criteria, and for other purposes.
Be it enacted by the Senate and House of Representatives of the United States of America in Congress assembled, That (a) (1) section 1 of the Federal Water Pollution Control Act (33 U.S.C. 466) is amended by inserting after the words “Section 1.” a new subsection (a) as follows:
(a) The purpose of this Act is to enhance the quality and value of our water resources and to establish a national policy for the prevention, control, and abatement of water pollution.
Federal Water Pollution Control Administration
Sec. 2. Effective ninety days after the date of enactment of this section there is created within the Department of Health, Education, and Welfare a Federal Water Pollution Control Administration (hereinafter in this Act referred to as the “Administration”).
Grants for Research and Development
Sec. 6. (a) The Secretary is authorized to make grants to any State, municipality, or intermunicipal or interstate agency for the purpose of assisting in the development of any project which will demonstrate a new or improved method of controlling the discharge into any waters of untreated or inadequately treated sewage or other waste from sewers which carry storm water or both storm water and sewage or other wastes, and for the purpose of reports, plans, and specifications in connection therewith. The Secretary is authorized to provide for the conduct of research and demonstrations relating to new or improved methods of controlling the discharge into any waters of untreated or inadequately treated sewage or other waste from sewers which carry storm water or both storm water and sewage or other wastes, by contract with public or private agencies and institutions and with individuals without regard to sections 3648 and 3709 of the Revised Statutes, except that not to exceed 25 per centum of the total amount appropriated under authority of this section for any fiscal year may be expended under authority of this sentence during such fiscal year.
(b) Federal grants under this section shall be subject to the following limitations: (1) No grant shall be made for any project pursuant to this section unless such project shall have been approved by an appropriate State water pollution control agency or agencies and by the Secretary; (2) no grant shall be made for any project in an amount exceeding 50 per centum of the estimated reasonable cost thereof as determined by the Secretary; (3) no grant shall be made for any project under this section unless the Secretary determines that such project will serve as a useful demonstration of a new or improved method of controlling the discharge into any water of untreated or inadequately treated sewage or other waste from sewers which carry storm water or both storm water and sewage or other wastes.
(c) There are hereby authorized to be appropriated for the fiscal year ending June 30, 1966, and for each of the next three succeeding fiscal years, the sum of $20,000,000 per fiscal year for the purposes of this section. Sums so appropriated shall remain available until expended. No grant or contract shall be made for any project in an amount exceeding 5 per centum of the total amount authorized by this section in any one fiscal year.
(3) Standards of quality established pursuant to this subsection shall be such as to protect the public health or welfare, enhance the quality of water and serve the purposes of this Act. In establishing such standards the Secretary, the Hearing Board, or the appropriate State authority shall take into consideration their use and value for public water supplies, propagation of fish and wildlife, recreational purposes, and agricultural, industrial, and other legitimate uses.
(5) The discharge of matter into such interstate waters or portions thereof, which reduces the quality of such waters below the water quality standards established under this subsection (whether the matter causing or contributing to such reduction is discharged directly into such waters or reaches such waters after discharge into tributaries of such waters), is subject to abatement in accordance with the provisions of paragraph (1) or (2) of subsection (g) of this section, except that at least 180 days before any abatement action is initiated under either paragraph (1) or (2) of subsection (g) as authorized by this subsection, the Secretary shall notify the violators of other interested parties of the violation of such standards. In any suit brought under the provision of this subsection the court shall receive in evidence a transcript of the proceedings of the conference and hearing provided for in this subsection, together with the recommendations of the conference and Hearing Board and the recommendations and standards promulgated by the Secretary, and such additional evidence, including that relating to the alleged violation of the standards, as it deems necessary t a complete review of the standards and to a determination of all other issues relating to the alleged violation. The court, giving due consideration to the practicability and to the physical and economic feasibility of complying with such standards, shall have jurisdiction to enter such judgment and orders enforcing such judgment as the public interest and the equities of the case may require.
(6) Nothing in this subsection shall (A) prevent the application of this section to any case to which subsection (a) of this section would otherwise be applicable, or (B) extend Federal jurisdiction over water not otherwise authorized by this Act.
(7) In connection with any hearings under this section no witness or any other person shall be required to divulge trade secrets or secret processes.
Public Law 89-235
Authorizing and requesting the President to extend through 1966 his proclamation of a period to “See the United States,” and for other purposes.
Resolved by the Senate and House of Representatives of the United States of America in Congress assembled, That the president is authorized and requested (1) to extend through 1966 the period designated pursuant to the joint resolution approved August 11, 1964 (Public Law 88-416), as a period to see the United States and its territories; (2) to encourage private industry and interested private organizations to continue their efforts to attract greater numbers of the American people to the scenic, historical, and recreational areas and facilities of the United States of America, its territories and possessions, and the Commonwealth of Puerto Rico; and (3) to issue a proclamation specially inviting citizens of other ceremonials to be celebrated in 1966 in the Unite States of America, its territories and possessions, and the Commonwealth of Puerto Rico.
Sec. 2. The President is authorized to publicize any proclamations issued pursuant to the first section and otherwise to encourage and promote vacation travel within the United States of America, its territories and possessions, and the Commonwealth of Puerto Rico, both by American citizens and by citizens of other countries, through such departments or agencies of the Federal Government as he deems appropriate, in cooperation with State and local agencies and private organizations.
Sec. 3. For the purpose of the extension provided for by this joint resolution, the President is authorized during the period of such extension to exercise the authority conferred by section 3 of the joint resolution approved August 11, 1964 (Public Law 88-416), and for such purpose may extend for such period the appointment of any person serving as National Chairman pursuant to such section.
Approved October 2, 1965.
U.S. CONGRESS. “THE WATER QUALITY ACT OF 1965.” 79 STAT. 903, 70 STAT. 498. WASHINGTON, DC: U.S. CONGRESS, OCTOBER 2, 1965.
Barlow, Maude. Blue Covenant: The Global Water Crisis and the Coming Battle for the Right to Water. New York: New Press, 2008.
Davis, Devra Lee. When Smoke Ran Like Water: Tales of Environmental Deception and the Battle Against Pollution. Oshkosh, WI: Basic Books, 2004.
Morris, Robert. The Blue Death: Disease, Disaster, and the Water We Drink. New York: Harper Collins, 207.
U.S Environmental Protection Agency (EPA). “Water Pollution.” http://www.epa.gov/ebtpages/watewaterpollution.html (accessed May 11, 2008).
World Heath Organization. “Water, Sanitation, and Hygiene.” http://www.who.int/water_sanitation_health/en/ (accessed May 11, 2008).
Brian D. Hoyle
Water Pollution: Freshwater
Water Pollution: Freshwater
Freshwater pollution is the contamination of inland water (not saline) with substances that make it unfit for its natural or intended use. Pollution may be caused by fecal waste, chemicals, pesticides, petroleum, sediment, or even heated discharges. Polluted rivers and lakes are unfit for swimming or fishing; polluted water is unsafe to drink.
For centuries, fecal waste and other pollutants were dumped in rivers, with "dilution the solution" to pollution. In the mid-twentieth century, many American rivers and streams were open sewers, choking on everything from human waste to highly toxic industrial discharges. New York City alone pumped a half billion gallons of raw sewage into its harbor every day. As pollution levels grew, so did the impacts. "No swimming" signs became the norm. Lake Erie was dying. The Hudson River's commercial striped bass fishery, once valued at $40 million a year, was closed and it became illegal to sell oysters from Oyster Bay, Long Island. And then, in June 1969, Ohio's Cuyahoga River caught fire.
The damning image of a river in flames is credited by many for passage of the Federal Water Pollution Control Act of 1972. The U.S. Environmental Protection Agency (EPA) set standards to regulate the discharge of industrial and municipal waste—so-called end-of-the-pipe pollution. With them came significant federal funding to help localities improve wastewater treatment. Billions of dollars have been invested since 1972 building and upgrading sewage treatment facilities.
Improvements in municipal wastewater treatment have been matched by progress in the private sector. Nationally, more than thirty thousand major industrial dischargers pretreat their wastewater before it enters local sewers. By 2000, some 75 percent of toxic discharges, including heavy metals and PCBs, were being prevented.
Surface Water Pollution
Freshwater makes up less than three percent of earth's water, but is the source of virtually all drinking water. In 2002, each U.S. household used an average of 94,000 gallons of water per year. Some 55 percent of that water comes from reservoirs, rivers, and lakes, and a 2000 survey published in EPA's National Water Quality Inventory found almost 40 percent of U.S. rivers and 45 percent of lakes are polluted. These sources, called surface water, are vulnerable to pollution discharged out of pipes and precipitating out of the air but the primary source of their pollution today is runoff, pollutants washing off the land.
These nonpoint or scattered sources are not easily traceable. Pesticides and fertilizers used in agriculture and on golf courses and suburban lawns account for a major portion of nonpoint source pollution. Runoff from parking lots and roads flush spilled oil and gasoline and road salt into lakes and streams. Runoff containing manure from livestock and poultry producers has been a major source of surface water pollution. More than 150 pathogens found in livestock manure pose risks to humans. In 2003, concentrated animal feeding operation guidelines, or CAFO standards, were finalized requiring inspection of waste lagoons and outdoor manure tanks, as well as permits for applying manure on land.
Air pollutants such as dioxin and mercury along with sulfur and nitrogen oxides precipitate into lakes and rivers by rainfall in the form of acid rain. More than 95 percent of rainwater tested at four sites in Indiana between 2001 and 2002 contained unsafe levels of mercury according to a National Wildlife Federation report.
Point sources, such as chemical and municipal wastewater treatment plants, were the leading source of contamination for about ten percent of river and lake water according to the 2000 National Water Quality Inventory. Toxic chemicals, although now regulated, can still be discharged directly into surface water. AK Steel Corporation in Pennsylvania discharged the largest amount of any industrial pollutant, about 28 million pounds of nitrate compounds, to surface water between 1998 and 2000, according to the Toxic Release Inventory.
Other sources of surface water pollution include silt washed into streams and lakes that smothers organisms on the lake floor, upsetting or destroying aquatic ecosystems. Thermal pollution such as an influx of warm water from cooling towers for power ecosystems. plants also has a detrimental effect on aquatic
The recent discovery of surface-water contamination by minute amounts of pharmaceuticals and personal-care products, including synthetic hormones from birth control pills, is being investigated to determine whether it poses a threat to humans, aquatic species, or wildlife. Water Quality Act amendments of 1987 established a $400-million program to help states to develop and implement nonpoint source management programs based on watershed protection.
Water contained in the pores of soil or in aquifers is called groundwater. About 40 percent of U.S. municipal water comes from groundwater and an additional forty million people, including most of the rural population, draw drinking water from domestic wells. Groundwater, while protected by the filtering action of soil, can be contaminated by leaking municipal landfills, sewage lagoons, and chemicals from industrial activity. Centers for Disease Control data shows that 318 waterborne disease outbreaks associated with groundwater systems occurred between 1971 and 1996. Leaking underground oil tanks and spills at gas stations account for oil and other chemicals such as benzene and methyl-tertiary-butyl ether (MBTE) found in ground-water. More than 400,000 leaking underground storage tanks were reported in the United States in 2001. Pesticides and agricultural fertilizers drain into groundwater polluting it with carcinogenic chemicals and nitrates.
The Safe Drinking Water Act of 1974 (SWDA) regulates groundwater. More than eighty possible contaminants are monitored, including carcinogens such as tetrachloroethylene, discharged from dry cleaners. Health effects of these contaminants range from increased cancer risk, intestinal lesions, kidney damage, and reproductive difficulties, to gastrointestinal distress. Municipal and private water suppliers are responsible for seeing that contaminants do not exceed the limits set by the EPA.
Human and Environmental Health Effects
Fertilizer, animal manure, and waste-treatment plant effluent all contain nutrients that stimulate excessive plant and algal growth in freshwater bodies. When the plants die and decompose, dissolved oxygen is depleted, causing die-offs of fish and other species living in the water. Persistent organochlorine insecticides, such as DDT, deposited in lake sediments can bioaccumulate, harming the fish and birds that eat them. Pyrethroid insecticides, though derived from chrysanthemums, are extremely toxic to aquatic organisms. Estrogen-mimicking substances such as some pesticides and industrially produced chemicals have been shown to interfere with the reproductive system of fish.
Human and animal fecal waste contain disease-carrying organisms such as the bacterium Escherichia coli (E. coli) and pathogens that causes cholera, typhoid, and cryptosporidiosis. Cholera is rarely seen in the United States, but E. coli outbreaks are not rare, and in 1993, more than fifty people died, and an estimated 400,000 became ill from a massive outbreak of cryptosporidiosis in Milwaukee, Wisconsin. The outbreak was attributed to a failure in drinking water treatment, allowing the cyst form of the parasite, introduced by animal waste, to pass into tap water and be ingested. Ten outbreaks of cryptosporidiosis were reported in the United States between 1990 and 2000.
Mercury bioaccumulates in fish and can damage the nervous systems and brains of humans. It can interfere with normal behavior in birds, such as loons, causing them to spend less time looking for food or incubating eggs. About one-quarter of breeding adult loons have higher-than-normal (10 parts per million) levels of mercury. To protect people from eating contaminated fish, states and local governments post fish-consumption advisories when contaminant levels become unsafe. There were 2,800 advisories posted in the United States in 2002, alerting people to high levels of mercury, PCBs, chlordane, dioxins, and DDT in fish.
Prevention and Abatement
Once water is contaminated, it is difficult, expensive, and sometimes impossible to remove pollutants. Technologies to remove contaminants from groundwater are air stripping, granular activated carbon, and advanced oxidation. Air stripping involves pumping out the contaminated water, then heating it to evaporate the contaminant. The cleaned water is reinjected into the ground. Pumping out contaminated water and absorbing the pollutant on activated charcoal can remove less volatile compounds. Ninety percent of trichloroethylene was removed from NASA's launch complex thirty-four groundwater cleanup site on Cape Canaveral Air Force Station by thermal treatment. In this method an electric current heats soil and water, evaporating some water and the contaminant, which is carried out of the ground by the force of the steam and collected in recovery wells.
Preventing pollution is obviously important. Drinking water suppliers have discovered that watershed protection is cost-effective because it reduces pollution and cuts the cost of drinking water treatment. A watershed is the area that drains into surface or groundwater and keeping that area free from development and agricultural runoff are among the goals of watershed protection. The Barnes Aquifer in Massachusetts supplies water to sixty thousand residents and the aquifer's recharge area is under heavy development pressure from large-scale residential subdivisions. Municipal wells have been contaminated with traces of ethylene dibromide and trichloroethylene. After learning about watershed protection, citizens voted against proposed changes to zoning that would have increased the number of new homes and increased the potential for groundwater pollution. And by investing $1 billion in watershed protection, New York City, with an enormous reservoir system, has avoided having to build water-filtration facilities, saving construction costs of some $8 billion.
The United Nations (UN) theme for World Environment Day 2003 was "Water: Two Billion People are Dying for It!" It was not en exaggeration. The UN reports that one person in six lives without regular access to safe drinking water. Over twice that number—2.4 billion people—lack access to adequate sanitation. Water-related diseases kill a child every eight seconds, and are responsible for 80 percent of all illnesses and deaths in the developing world. Cholera outbreaks, due to water contaminated with raw sewage, occur regularly in India and Bangladesh and less frequently in many other countries. In Africa in 1997, 5,853 deaths due to cholera were reported to the World Health Organization. It is a situation, the UN said, "made all the more tragic by our long-standing knowledge that these diseases are easily preventable."
see also: Acid Rain; Agriculture; Clean Water Act; Cryptosporidiosis; DDT (Dichlorodiphenyl trichloroethane); Health, Human; Nonpoint Source Pollution; PCBs (Polychlorinated Biphenyls); Point Source; Snow, John; Wastewater Treatment; Water Treatment.
Pielou, E.C. (1998). Fresh Water. Chicago and London: The University of Chicago Press.
Natural Resources Defense Council. "What's on Tap: Grading Water in 19 U.S. Cities." Available from http://www.nrdc.org/water/drinking/uscities/contents.asp.
U.S. Environmental Protection Agency. Browse EPA Topics. Available from http://www.epa.gov/ebtpages/alphabet.html.
U.S. Environmental Protection Agency. Clean Water Act. Available from http://www.epa.gov/r5water/cwa.htm.
U.S. Environmental Protection Agency. Concentrated Animal Feeding Operation Final Rule. Available from http://cfpub.epa.gov/npdes/afo/cafofinalrule.cfm.
U.S. Environmental Protection Agency. List of Drinking Water Contaminants and their MCLs. Available from http://www.epa.gov/safewater/mcl.html#mcls.
U.S. Environmental Protection Agency. Polluted Runoff (Nonpoint Source Pollution). Available from http://www.epa.gov/OWOW/NPS/facts/point1.htm.
U.S. Environmental Protection Agency. Proposed Groundwater Rule. Available from http://www.epa.gov/OGWDW/gwr.html.
U.S. Environmental Protection Agency. Safe Drinking Water Act. Available from http://www.epa.gov/safewater/sdwa/sdwa.html.
U.S. Environmental Protection Agency. 2000 National Water Quality Inventory. Available from http://www.epa.gov/305b/2000report.
U.S. Environmental Protection Agency's Water Science Great Lakes Initiative Topic. Available from http://www.epa.gov/ost/GLI/mixingzones/finalfact.html.
U.S. Environmental Protection Agency. Fish Advisories. Available from http://www.epa.gov/waterscience/fish.
U.S. Geological Survey National Water Quality Assessment Program. Available from http://water.usgs.gov/nawqa.
You can help prevent water pollution by simply not littering. Street trash that washes down storm drains is a major source of floatable debris. Properly dispose of used oil; oil poured down storm drains and sewers is a major source of petroleum pollution. Use nonphosphate detergents for dish and clothes washing. Don't overfertilize lawns and use integrated pest management practices to reduce pesticide use. Use hazardous waste collection programs to dispose of batteries, fluorescent lights that contain mercury, unused oil, paint remover, pesticides and old household chemicals.
The Great Lakes Basin includes areas of the eight Great Lakes states: New York, Pennsylvania, Ohio, Minnesota, Indiana, Illinois, Wisconsin, and Michigan. In 1995, the U.S. Environmental Protection Agency (EPA) and the Great Lakes states agreed to a plan called the Great Lakes Initiative, aimed at reducing pollution and restoring the health of the Great Lakes. The plan included setting water quality standards for twenty-nine pollutants. In 2000, the EPA initiated a ten-year phase-out of the use of mixing zones for bioaccumulative chemicals in the Great Lakes. The EPA says this ruling will reduce discharges of toxic chemicals by 700,000 pounds a year.
Water Pollution: Marine
Water Pollution: Marine
Marine pollution is the release of by-products of human activity that cause harm to natural marine ecosystems. The pollutants may be sewage, farm waste, toxic chemicals, or inert materials that may smother, choke, or strangle living organisms.
Sewage, Animal Waste, and Fertilizers
Sewage, animal waste, and chemical fertilizers all have a high content of nitrogen and phosphorus. Artificially high levels of these substances in the water promote excessive growth of microscopic or macroscopic plants, in a process called eutrophication . When these plants accumulate, die, and decay, they cause low oxygen content in the water. Even if sewage is treated to remove solids, the liquid discharged contains high levels of nitrogen and phosphorus. Intensive cultivation of animals in feedlots, or application of more fertilizer than a crop can absorb, also cause runoff rich in nitrogen and phosphorus that find their way into rivers and estuaries. Vehicle exhausts and industrial chimneys are large sources of nitrogen compounds that are transported in the atmosphere and deposited in coastal waters.
On a global scale, agricultural runoff is the most important source of eutrophication, but atmospheric deposition is the fastest-growing source. It is the largest source of nitrogen off the coast of the northeastern United States, in the western Baltic Sea, and in the western Mediterranean Sea. International agencies consider that, worldwide, eutrophication is the most serious pollution problem in coastal waters. For example, in the Gulf of Mexico, off the mouth of the Mississippi River, water near the bottom has severely reduced oxygen content over a very large area, sixteen thousand square kilometers (6,200 square miles) by 1998. Mobile animals such as fish and shrimp leave the hypoxic area, but sedentary animals such as clams and worms are killed in large numbers.
A classic example of eutrophication and its treatment occurred in the estuary of the River Thames, near London, England. In the 1950s the water was severely hypoxic for thirty-five kilometers (twenty-two miles) below London Bridge. After several sewage treatment plants were built, the water returned to a well-oxygenated state and migratory fish such as salmon once again ascend the river. In the case of the Mississippi River, treatment of the eutrophication is more difficult because runoff from agricultural land is the major cause of the problem, and more than half of the agricultural land in the United States drains into the Mississippi basin. Cleaning up the pollution would involve changes in farming methods on a national scale.
Eutrophication has important indirect effects. The plants known as sea grasses, which grow in the shallow water of estuaries , provide food and shelter for a wide range of animals, including geese, turtles, manatees, and fish. In eutrophicated water, the dense microscopic plant life significantly reduces the penetration of light and smothers the sea grasses. In Chesapeake Bay, Maryland, eutrophication caused an area of sea grasses to decrease by twothirds between 1960 and 1980, and there was a corresponding decrease in landings of fish and crabs. Similar effects have been observed in Australia.
Red tides, or harmful algal blooms, are associated with eutrophication. Single species of phytoplankton multiply at the expense of all other species
and become so abundant that the water is discolored. Many bloom species produce toxic substances. During the 1990s in estuaries located in the southeastern United States, there were numerous cases of blooms of Pfiesteria piscida, a dinoflagellate that produced a toxin which killed thousands of fish. The source of the nutrients support Pfiesteria is believed to be agricultural runoff or sewage discharge. Other types of blooms are ingested by shellfish, which become toxic for humans who consume them, causing partial paralysis, memory loss, or even death. Toxic blooms have been reported much more frequently in the 1990s than in the past, and the spread of eutrophication is believed to be a contributing factor.
Pollution and Coral Reefs
On coral reefs, eutrophication causes seaweed to grow and smother the corals. Several kinds of environmental problems interact with eutrophication to cause the deterioration of coral reefs. Overharvesting of the fish and invertebrates that eat seaweed accelerates the smothering. Careless development along coastlines and in river basins leads to soil erosion and the transport of heavy loads of silt and clay, which settle on the corals and smother them. Oil spills also take their toll. When corals are exposed to abnormally high water temperature, they respond by discharging the microscopic algae living within their tissues. Sometimes they recover, but often they die. These episodes, called coral bleaching, became much more frequent during the 1990s and are believed to be caused by global warming. The result of pollution and global warming is that at least half of the area of coral reefs in southeast Asia is in poor condition, and in parts of the Caribbean Sea only 5 percent of the reef area consists of living coral.
Metals and Organic Contaminants
Industrial effluents often contain metallic compounds. For example, Halifax, a small city in eastern Canada, discharged into its harbor during the 1990s about thirty-three tons of zinc and thirty-one tons of lead per year, with lesser amounts of copper and other metals. These metals are held in the sediment in a relatively inert form, but if stirred up into the water column, they become oxygenated and toxic. Tin is another common pollutant in harbors. It occurs as tributyltin (TBT), which is used as a component of antifouling paints on the undersides of ships. When taken up by shellfish, it accumulates in their tissues and has proved toxic to the shellfish and to organisms that consume them. The United States began to phase out TBT in 1988, and it will be banned internationally beginning in 2008.
Industry also produces organic compounds such as polychlorinated biphenyls (PCBs) and various pesticides. These accumulate in the fatty tissue of plants and animals low in the food chain, and as they pass through the food web to larger and long-lived animals, there is an increase in concentration of the substances in their fat, a process known as bioaccumulation. The St. Lawrence River, which drains the Great Lakes, has accumulated large amounts of organochlorines , which have amassed in the tissues of Beluga whales. During the 1990s, the level of this pollution was much reduced, and the whales have been protected from hunting, but their population fails to increase. Many animals have tumors and disease. There is mounting evidence that chronic exposure to contaminants causes suppression of the immune responses of marine mammals. Similar problems have occurred with seals in the Baltic Sea.
The most serious types of oil pollution occur when an oil tanker goes ashore or hits a reef and spills its contents. As the oil drifts ashore, great damage is done to beaches, rocky shores, salt marshes, or mangrove forests. Cleanup is often attempted using mechanical means, or the application of dispersants, with mixed results. Usually, a proportion of native organisms are killed, but given time, the lighter fractions of oil evaporate, while the heavier fractions are decomposed by photochemical processes and microorganisms. International law now requires that vessel owners be responsible for any loss of oil, damage to existing ecosystems, and the costs of recommended cleanup.
Chronic low levels of oil pollution, resulting from accidental spills when loading or unloading, or from washing out oil tanks, are widespread and of significant concern. For example, it has been determined that corals around an oil terminal in the Red Sea have experienced lower growth rates and poor reproduction as a result of chronic low-level oil pollution.
Oil pollution of the open ocean is also a major concern. When Thor Heyerdahl crossed the South Pacific on the raft Kon-Tiki in 1947 he reported pristine waters, but his Ra expedition across the Atlantic twenty-two years later encountered oil slicks on forty-three of fifty-seven days at sea. The International Convention for Prevention of Pollution from Ships was devised in 1973 and modified by the Protocol of 1978. Oceangoing vessels are subject to strict regulations concerning the discharge of oil, bilge water, and ballast water, and are forbidden to dump garbage and other solid waste. Accidental spills must be reported.
Marine beaches serve as natural traps for marine debris. Globally, the most common materials are plastics, followed by glass and metal. The chief dangers to marine life result from the ingestion of these fragments, which may block the gut, and from entangling, which may cause suffocation or prevent locomotion and feeding. In a survey of U.S. beaches close to urban centers, cigarette butts were the most abundant debris, followed by packaging items (boxes, bags, caps, lids), medical waste, and sewage. A high proportion of this material reached the sea by way of sewers. Even street litter can be washed into surface drains and then to the sea. The dumping of sewage and waste by ships is another source. Public revulsion at the state of U.S. beaches was a key factor in the enactment of stronger environmental protection laws, like the Ocean Dumping Ban Act of 1988 that prohibited the dumping of sewage into the ocean. On sites more remote from cities, pieces of rope and netting are the most common types of marine debris.
Reduction and Regulation of Marine Pollution
There is much that individuals can do to prevent marine pollution: avoid putting toxic substances into drains, avoid dropping litter, minimize the use of pesticides and fertilizers, reduce automobile emissions, and pressure your local government for sewage treatment in the community if it does not yet exist. Larger-scale problems require legislation and enforcement, ranging from the local laws of coastal states in the United States, through national laws such as the Clean Water Act and Clean Air Act, to international conventions such as the International Convention for the Prevention of Pollution from Ships. Such laws are effective only if they have the support of the people.
see also Acid Rain; Clean Water Act; Cryptosporidiosis; Fish Kills; Hypoxia; Mercury; Ocean Dumping; PCBs (Polychlorinated Biphenyls); Petroleum; Rivers and Harbors Appropriations Act; Snow, John; Water Treatment; Wastewater Treatment.
clark, r.b.; frid, c; and attrill, m. (2001). marine pollution, 5th edition. oxford, uk: oxford university press.
pelley, j. (1998). "is coastal eutrophication out of control?" environmental science and technology 32:462a–466a.
global investigation of pollution in the marine environment (gipme). "marine pollution programme." available from http://ioc.unesco.org/iocweb.
ocean conservancy. available from http://www.oceanconservancy.org.
Kenneth H. Mann
Coral grows a new layer each year, much as a tree adds a new ring each year. Scientists analyzing layers of Bermudan coral have discovered an environmental record dating back to the mid-1800s. Marine pollution can be measured across the Industrial Revolution. Marine levels of lead have dropped dramatically since the phaseout of leaded gasoline but levels of lead in the Atlantic are still double their preindustrial concentrations.
When Thor Heyerdahl, a Norwegian biologist (1914–2002), sailed the balsa wood raft named Kon-Tiki, from Peru to Polynesia in 1947, he saw no pollution in the Pacific Ocean. Just over twenty years later, in 1970, when sailing a papyrus reed boat from Morocco to Barbados, Heyerdahl saw extensive marine pollution including oily wastes, plastic bottles and other trash floating in the water. He radioed the United Nations to report that floating lumps of solidified, asphalt-like oil polluted over one thousand miles of the Atlantic Ocean. After seeing the extent of the ocean's pollution first hand, Heyerdahl became actively involved in fighting marine pollution. In 1999, with the Norwegian Shipowners Organization, he initiated the Thor Heyerdahl International Maritime Environmental Award to be given for improvement of the global environment.
Thousands of volunteers in every U.S. state and territory as well as in more than fifty other countries pick up tons of marine debris each fall in a one-day coastal cleanup. The Ocean Conservancy, which organizes the annual cleanup, collects data on the debris to determine sources of pollution. The most common item washed up on the shoreline? Cigarette butts and filters—a total of 1,640,614 were picked up in 2001. Volunteers also found 259 entangled animals, most snared in nylon fishing line.
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 582 highly toxic chemicals, which are produced, manufactured, and stored in locations across the United States. Some chemical plants incinerate toxic waste, 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) 33 U.S.C.A. § 1251 et seq., 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 65, and set effluent limitations for the 21 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.
Hipfel, Steven J. 2001. "Enforcement of Nonpoint Source Water Pollution Control and Abatement Measures Applicable to Federal Facilities, Activities and Land Management Practices under Federal and State Law." Environmental Lawyer 8 (September).
Houck, Oliver A. 2002. The Clean Water Act TMDL Program: Law, Policy, and Implementation. 2d ed. Washington, D.C.: Environmental Law Institute.
Ryan, Mark A., ed. 2003. The Clean Water Act Handbook. 2d ed. Chicago: Section of Environment, Energy, and Resources, American Bar Association.
Among the many environmental problems that offend and concern us, perhaps none is as powerful and dramatic as water pollution . Ugly, scummy water full of debris, sludge , and dark foam is surely one of the strongest and most easily recognized symbols of our misuse of the environment .
What is pollution? The verb "pollute" is derived from the Latin polluere : to foul or corrupt. Our most common meaning is to make something unfit or harmful to living things, especially by the addition of waste matter or sewage. A broader definition might include any physical, biological, or chemical change in water quality that adversely affects living organisms or makes water unsuitable for desired uses.
Paradoxically, however, a change that adversely affects one organism may be advantageous to another. Nutrients that stimulate oxygen consumption by bacteria and other decomposers in a river or lake, for instance, may be lethal to fish but will stimulate a flourishing community of decomposers. Whether the quality of the water has suffered depends on your perspective. There are natural sources of water contamination, such as poison springs, oil seeps, and sedimentation from erosion , but most discussions of water pollution focus on human-caused changes that affect water quality or usability.
The most serious water pollutants in terms of human health worldwide are pathogenic organisms. Altogether, at least 25 million deaths each year are blamed on these water-related diseases, including nearly two-thirds of the mortalities of children under five years old. The main source of these pathogens is from untreated or improperly treated human wastes. In the more developed countries, sewage treatment plants and other pollution control techniques have reduced or eliminated most of the worst sources of pathogens in inland surface waters. The United Nations estimates that 90% of the people in high-income countries have adequate sewage disposal, and 95% have clean drinking water.
For poor people, the situation is quite different. The United Nations estimates that three-quarters of the population in less-developed countries have inadequate sanitation , and that less than half have access to clean drinking water. Conditions are generally worse in remote, rural areas where sewage treatment is usually primitive or nonexistent, and purified water is either unavailable or too expensive to obtain. In the 33 poorest countries, 60% of the urban population have access to clean drinking water but only 20% of rural people do.
This lack of pollution control is reflected in surface and groundwater quality in countries that lack the resources or political will to enforce pollution control. In Poland, for example, 95% of all surface water is unfit to drink. The Vistula River, which winds through the country's most heavily industrialized region, is so badly polluted that more than half the river is utterly devoid of life and unsuited even for industrial use. In Russia, the lower Volga River is reported to be on the brink of disaster due to the 300 million tons (272.2 million metric tons) of solid waste and 20 trillion L (5 trillion gal) of liquid effluent dumped into it annually.
The less-developed countries of South America, Africa, and Asia have even worse water quality than do the poorer countries of Europe. Sewage treatment is usually either totally lacking or woefully inadequate. Low technological capabilities and little money for pollution control are made even worse by burgeoning populations, rapid urbanization, and the shift of heavy industry from developed countries where pollution laws are strict to less developed countries where regulations are more lenient.
In Malaysia, 42 of 50 major rivers are reported to be "ecological disasters." Residues from palm oil and rubber manufacturing, along with heavy erosion from logging of tropical rain forests, have destroyed all higher forms of life in most of these rivers. In the Philippines, domestic sewage makes up 60–70% of the total volume of Manila's Pasig River. Thousands of people use the river not only for bathing and washing clothes, but also as their source of drinking and cooking water. China treats only 2% of its sewage. Of 78 monitored rivers in China, 54 are reported to be seriously polluted. Of 44 major cities in China, 41 use "contaminated" water supplies, and few do more than rudimentary treatment before it is delivered to the public.
Pollution control standards and regulations usually distinguish between point and nonpoint pollution sources. Factories, power plants , sewage treatment plants, underground coal mines, and oil wells are classified as point sources because they discharge pollution from specific locations, such as drain pipes, ditches, or sewer outfalls. These sources are discrete and identifiable, so they are relatively easy to monitor and regulate. It is generally possible to divert effluent from the waste streams of these sources and treat it before it enters the environment.
In contrast, nonpoint sources of water pollution are scattered or diffused, having no specific location where they discharge into a particular body of water. Nonpoint sources include runoff from farm fields, golf courses , lawns and gardens, construction sites, logging areas, roads, streets, and parking lots. Multiple origins and scattered locations make this pollution more difficult to monitor, regulate, and treat than point sources.
Desert soils often contain high salt concentrations that can be mobilized by irrigation and concentrated by evaporation, reaching levels that are toxic for plants and animals. Salt levels in the San Joaquin River in central California rose about 50% between 1930 to 1970 as a result of agricultural runoff. Salinity levels in the Colorado River and surrounding farm fields have become so high in recent years that millions of acres of valuable croplands have had to be abandoned. The United States is building a huge desalination plant at Yuma, Arizona, to reduce salinity in the river. In northern states, millions of tons of sodium chloride and calcium chloride are used to melt road ice in the winter. The corrosive damage to highways and automobiles and the toxic effects on vegetation are enormous. Leaching of road salts into surface waters has a similarly devastating effect on aquatic ecosystems.
Acids are released by mining and as by-products of industrial processes, such as leather tanning, metal smelting and plating, petroleum distillation, and organic chemical synthesis. Coal mining is an especially important source of acid water pollution. Sulfides in coal are solubilized to make sulfuric acid. Thousands of miles of streams in the United States have been poisoned by acids and metals, some so severely that they are essentially lifeless.
Thousands of different natural and synthetic organic chemicals are used in the chemical industry to make pesticides, plastics , pharmaceuticals, pigments, and other products that we use in everyday life. Many of these chemicals are highly toxic. Exposure to very low concentrations can cause birth defects , genetic disorders, and cancer . Some synthetic chemicals are resistant to degradation, allowing them to persist in the environment for many years. Contamination of surface waters and groundwater by these chemicals is a serious threat to human health.
Hundreds of millions of tons of hazardous organic wastes are thought to be stored in dumps, landfills, lagoons, and underground tanks in the United States. Many, perhaps most, of these sites are leaking toxic chemicals into surface waters or groundwater or both. The Environmental Protection Agency (EPA) estimates that about 26,000 hazardous waste sites will require cleanup because they pose an imminent threat to public health, mostly through water pollution.
Although the oceans are vast, unmistakable signs of human abuse can be seen even in the most remote places. Garbage and human wastes from coastal cities are dumped into the ocean. Silt , fertilizers, and pesticides from farm fields smothered coral reefs, coastal spawning beds, and over-fertilize estuaries. Every year millions of tons of plastic litter and discarded fishing nets entangle aquatic organisms, dooming them to a slow death. Generally coastal areas, where the highest concentrations of sea life are found and human activities take place, are most critically affected.
The amount of oxygen dissolved in water is a good indicator of water quality and of the kinds of life it will support. Water with an oxygen content above 8 parts per million (ppm) will support game fish and other desirable forms of aquatic life. Water with less than 2 ppm oxygen will support only worms, bacteria, fungi , and other decomposers. Oxygen is added to water by diffusion from the air, especially when turbulence and mixing rates are high, and by photosynthesis of green plants, algae, and cyanobacteria. Oxygen is removed from water by respiration and chemical processes that consume oxygen.
In spite of the multitude of bad news about water quality, some encouraging pollution control stories are emerging. One of the most outstanding examples is the Thames River in London. Since the beginning of the Industrial Revolution, the Thames had been little more than an open sewer, full of vile and toxic waste products from domestic and industrial sewers. In the l950s, however, England undertook a massive cleanup of the Thames. More than $250 million in public funds plus millions more from industry were spent to curb pollution. By the early l980s, the river was showing remarkable signs of rejuvenation. Oxygen levels had rebounded and some 95 species of fish had returned, including the pollution-sensitive salmon , which had not been seen in London for 300 years. With a little effort, care, and concern for the environment, similar improvements can develop elsewhere.
[William P. Cunningham ]
Mayberck, M. Global Freshwater Quality: A First Assessment. Oxford, UK: Blackwell Reference, 1990.
Protecting Our Future Today. Washington, DC: Environmental Protection Agency, 1991.
Water pollution exists when water is contaminated by impurities or its quality is otherwise adversely affected, for example, by solid matter or thermal discharges. Water pollution problems have a long history that can be traced to antiquity, and the attempts of communities to control such problems have an equally long track record. The nature of water pollution problems has changed over time, and their geographic scale has steadily increased, as has the scale of institutional solutions that have been adopted to control them. This entry explores the key changes in the nature and scale of water pollution and in the institutional solutions that have been adopted as a response to it.
Pollution of water by human wastes was a key public health problem when today’s developed countries urbanized in the 1800s. Urban life expectancies decreased because contaminated water supplies caused epidemics of cholera, typhoid fever, and other water-borne diseases and increased people’s susceptibility to all illnesses. These problems were initially local, when wells and ground water were used for water supplies, and communities responded to them with local public health and sanitation regulations. The construction of networked water supplies and sewer systems after the mid-1800s increased the scale of water pollution. Local regulations proved powerless when sources of pollution were increasingly outside the local jurisdiction. This situation gave rise to the first state and national water pollution policies, which successfully safeguarded public health but which largely failed to improve in-stream water quality.
The nature of water pollution changed in industrialized countries around the time of World War II (1939–1945) because the war effort and postwar reconstruction resulted in the rapid growth of industrial production and increased discharge of industrial effluents. New innovations such as organic pesticides and synthetic detergents also proved potent water pollutants. The decades after the war witnessed several widely publicized environmental disasters, including mercury pollution in Minamata, Japan, that caused “Minamata disease” in the 1950s; the Torrey Canyon (1967) and Amoco Cadiz (1978) supertanker disasters in Europe; and the Santa Barbara, California, oil spill in 1969. Furthermore, there was controversy over asbestos-containing discharges from Reserve Mining into Lake Superior in Silver Bay, Minnesota, in the 1970s; the leak of toxic chemicals from the Sandoz factory in Basel, Switzerland, in 1986; and the cyanide spill from a gold mine in Baia Mare, Romania, which polluted the Tisza and Danube rivers in 2000. More recently, in November 2005, an explosion in a chemical plant in Jilin, China, polluted the Songhua River with benzene and nitrobenzene.
Water pollution continues to be a public health problem in the developing world. Worldwide, one child out of six under five years of age dies of a diarrheal disease such as cholera, typhoid fever, dysentery, and gastroenteritis, which are caused by the contamination of water by human wastes. Moreover, weak enforcement or the nonexistence of environmental and safety regulations in developing countries means that agriculture, horticulture, and mining are major sources of toxic water pollutants such as pesticides and mercury. Such pollutants have caused grave public health consequences across the developing world, but particularly in severely polluted areas such as the Aral Sea region in Central Asia. In some places, such as in Bangladesh, naturally occurring arsenic pollutes certain layers of ground water on which many communities depend for their water supply.
Most developed countries have adopted water pollution policies that have reduced conventional water pollutants from point sources. Conventional pollutants include biochemical oxygen demand (BOD), total suspended solids (TSS), fecal coliform, oil and grease, and pH (acidity and alkalinity). Point sources include municipal sewage treatment plants, industrial establishments, and other facilities, which only contributed about half of all conventional pollutants in the United States when the Clean Water Act of 1972, with its focus on point sources, was adopted. Water pollution originating from nonpoint sources, such as agriculture, streets and roads, and storm sewers, was not originally controlled with the same level of effectiveness. National policies have also been less successful in reducing the amount of nonconventional pollutants, such as those of toxic chemicals. More recently, market-based instruments such as fertilizer, manure, and pesticide taxes have been used in many countries for controlling water pollution from nonpoint sources. Other market based instruments, particularly tradable effluent permits and sewerage charges, have increasingly been used also for controlling conventional water pollutants.
The incentives and capacity of states to control pollution from sources that lie outside their jurisdictions is limited, however. International environmental agreements have been negotiated to address this problem, including early agreements on the transportation of dangerous substances on the River Rhine in western Europe, which came into force between 1900 and 1902, and the Boundary Waters Treaty between the United States and Canada, which took effect in 1909. International agreements since 1970 have addressed, for example, the pollution of the marine environment by oil and dumping; the pollution of transboundary bodies of water such as the Baltic Sea, the North Sea, and the Mediterranean; the elimination of persistent organic compounds; and the international transport of hazardous materials and liability for damages caused by their transport. Some of these conventions, such as the 1992 Baltic Sea Convention, have been successful, while others have made little difference to the quality of the marine environment to date.
SEE ALSO Pollution; Pollution, Air; Pollution, Noise
Paavola, Jouni. 2004. Law: Water and Air Pollution. In The Encyclopedia of World Environmental History, Vol. 2, eds. Shepard Krech III, J. R. McNeill, and Carolyn Merchant, 778–786. London and New York: Routledge.
Tarr, Joel A. 1996. The Search for the Ultimate Sink: Urban Pollution in Historical Perspective. Akron, OH: Akron University Press.
Pollution is defined as the addition of harmful substances into the ecosystem (the network of interactions between living organisms and their environment). Pollutants might be slightly harmful to humans, but very harmful to aquatic life. For instance, in certain lakes and rivers when acid rain (rain polluted with acidic chemicals) falls upon them, toxic (poisonous) metals that cause fish to die are released from sediments (particles of soil, sand, and minerals, and animal or plant matter washed from land into water). These metals—chromium, aluminum, and mercury are just a few—are harmful to fish. But humans would have to ingest much larger quantities than the aquatic or marine life. The toxins also accumulate in the tissues of fish as they eat other fish (ingest) or plants containing toxins. If one were to catch and eat a fish that has a high content of toxins in them the human is affected too. Metals are not the only pollutants that are of concern, as evidenced by oil spills that kill marine life in large quantities and persist on beaches and in sediments for a long time. Industrial processes produce harmful waste, and often this is discharged into a nearby stream, river, or ocean. There are many ways to cause pollution and many types of pollutants.
Levels of pollution
Transportation is a leading source of pollution, both in the atmosphere (mass of air surrounding Earth) and in water reserves. Every time oil or gasoline is spilled on the roadway, it eventually is transported to the nearest water reserve. Many of these reserves are groundwater. Groundwater is freshwater that resides in rock and soil layers beneath Earth's land surface, and groundwater can eventually transport pollutants into rivers, streams, and the sea. Thus, pollutants can come from large areas or specific areas. These are referred to as non-point source and point-source pollution, respectively.
If the source of pollution is able to be identified and "pointed" to, the source of pollution is point-source. Point sources include drainage pipes from factories, leaky underground gasoline tanks, and places where people discard used motor oil. Non-point sources are far more reaching, such as the transportation example. Not only do toxic chemicals come from leaky automobiles and gasoline spills, they come from exhaust fumes that are taken into the atmosphere and then are brought back down to earth in rain. A smokestack that releases hazardous gasses into the air might very well be responsible for acid rain many miles away, but it would be hard to identify the source if the factory was a sufficient distance from the site of the rainfall event.
How do pollutants affect the world around us? An oil spill renders seabirds flightless, because the oil coats their feathers. Oil makes areas of waterfront land uninhabitable, and some animals (turtles) bury eggs in the sand and thus they are affected too. Metal contamination from industrial processes—like the ones mentioned above as well as lead, arsenic, antimony, and cadmium—are by-products of the manufacturing of many types of goods. It turns out that chemicals contained in oil and gasoline are carcinogenic, which means they can cause cancer. The metals, known as heavy metals, can cause damage to many organs in one's body, most notably the liver and the brain.
Even "land based" pollutants eventually make their way into groundwater, streams, and rivers. Many older houses were painted with paint that contained lead, and that anyone who eats paint chips from these older homes can develop mental difficulties because lead is very toxic. Mercury is used in thermostats in many homes, in thermometers, and in industry. It is also used in batteries, but to a limited extent. Mercury can combine with other elements to form one of the most dangerous chemicals known to man, dimethyl mercury. A single drop can kill a person in less than one month. Arsenic is used, among other things, to make lumber resist rotting. However, the arsenic gets soaked from the wood eventually and ends up in the ecosystem.
Untreated sewage from humans and animals poses a problem to water sources. Because of limited facilities in developing countries to handle the processing of this waste, many times it is simply dumped into rivers or oceans untreated. These substances contain disease-causing organisms and present a danger to the health of humans and animals.
Sewage disposal is not only a problem in developing countries; in May 2004, the city of Milwaukee, Wisconsin, dumped 1.5 billion gallons (5.6 million liters) of untreated sewage into Lake Michigan, enough sewage to fill 5,000 Olympic-sized swimming pools. The problem stems from Milwaukee's storm drainage system, which is interconnected with the sewer system. After a heavy rain, the storm drainage pipes and sewer pipes both fill with runoff and the sewers cannot handle the extra load. The result is an overflow and Milwaukee water officials were forced to dump the sewage rather than allow it to back up directly into people's bathrooms and basements. Milwaukee officials are studying different plans in order to choose the best method of separating the city's storm and sewer systems.
Sources and types of pollutants
The population of Earth is over six billion people, and not all countries adhere to the same regulations about protecting the environment. Before the industrial revolution in the late nineteenth century, pollution of sea water and surface waters was largely attributable to natural causes, such as drought (prolonged below-normal levels of rain) conditions that in turn, led to increased concentrations of various compounds in the water supply. When automobiles and gasoline-powered machinery became available, pollution surged, due to increased output of consumer goods and machinery. Conservation laws in many developed countries have helped to correct pollution in many air and water sources since the time of the industrial revolution. Some developing countries still use highly-polluting products such as fuel with lead components, and environmental scientists are now concentrating their efforts in studying the long-term effects of water and air pollution on a worldwide scope.
Not all pollution is attributed to oil spills, industry, and transportation. Humans contribute to pollution in the course of everyday activities. Washing automobiles, lawn fertilizers, cleaning products eventually end up in the water supply. The soap and shampoo from bathing, disinfectants for cleaning the kitchen and bathroom, nail polish, and the waxes and oils for cleaning floors are just a few examples of home products that contribute to the pollution of the water supply. Lawnmowers are very inefficient when it comes to cleaning exhaust, so the gasses end up in the atmosphere and fall to Earth in rain. Medical products, such as antibiotics contain substances that are helpful to some organisms but not to others, and the introduction of these substances can result in the killing of aquatic life or altering the reproductive cycles of various species.
Based on many years of scientific studies, there are regulations from the U.S. government as to acceptable levels of particular pollutants. For instance, the human body needs chromium, but very little of it, and a person gets it automatically from eating a balanced diet. Iron is critical for making sure oxygen gets transported with blood cells but too much iron is dangerous. The Environmental Protection Agency (EPA) is a U.S. government division that monitors the levels of contaminants (pollutants) in the ecosystem. Based on studies with animals, plants, and humans, the EPA has determined what levels of many pollutants can be ingested with no proven risk of health trouble. Adhering to these standards is expensive because industries that produce pollutants must buy expensive equipment to filter the harmful chemicals (as well as gasses) from the waters they discharge. The price is passed along to the consumer by raising product prices. This was the case in the early 1980s with gasoline, when adding a lead-based compound to gasoline prolonged engine life. The risks of the added lead outweighed the benefits, and the government decided to ban lead-products in gasoline and replace them with a chemical that essentially does the same job, but is non-toxic.
A major concern of the damage of the quality of ocean waters is the dumping of garbage. It is a common practice to load barges with millions of pounds of refuse every day and sail offshore for several miles, then dump the contents into the sea. Many items in these garbage barges are toxic, such as metals from old batteries and medical waste. Other items, such as decaying foodstuffs, are dangerous sources of bacteria that are harmful for all life. Although dumping garbage far out to sea is supposed to result in natural degradation (breaking apart), various currents, storms, and other physical events often lead to garbage washing back to shore, where it again enters the pollution cycle.
Laurie Duncan, Ph.D.
For More Information
Maclean, Norman. A River Runs Through it. Washington, DC: Island Press, 2003.
Postel, Sandra, and Brian Richter. Rivers for Life: Managing Water for People and Nature. Washington, DC: Island Press, 2003.
Vigil, Kenneth M. Clean Water: An Introduction to Water Quality and Pollution Control. 2nd ed. Corvallis: Oregon State University Press, 2003.
"Facts About Water Pollution." Project Clean Water, County of Santa Barbara.http://www.countyofsb.org/project_cleanwater/facts.htm (accessed on September 8, 2004).
Water pollution occurs when undesirable foreign substances are introduced into natural water. The substances may be chemical or biological in nature. Common pollutants include human or animal waste; disease-producing organisms; radioactive materials; toxic metals such as lead or mercury; agricultural chemicals such as pesticides, herbicides, or fertilizers; acid rain ; and high-temperature water discharged from power plants, often called "thermal pollution." Pollutants in water are dangerous for human or animal consumption and harm crops. High temperatures may cause algae to grow rapidly, rendering water unfit for consumption.
Point sources of pollution, such as an oil leak from a pipeline or chemical waste from a factory, can often be controlled. Nonpoint sources, such as runoff sediment and nitrate-rich water from feedlots represent larger amounts of pollution and are difficult to identify and remedy. Pollution from nonpoint sources may pass into streams or aquifers, covering a wide area.
Although water has been identified on several planets, none has as much water as Earth, of which 70 percent is covered with water. Approximately 97.4 percent of the water on Earth is found in oceans and is too salty for human consumption. An additional 2.6 percent is freshwater found in underground bodies of water called aquifers or frozen in glaciers or polar ice caps. Less than 0.02 percent of Earth's water is present in lakes, rivers, or the atmosphere.
In a few places, water is pure enough to drink directly from wells or springs, but increasingly water must be treated to remove dangerous contaminants, and substances such as chlorine, chloramines, or ozone must be added to kill harmful bacteria.
Pollutants in water are commonly measured and reported as parts per million (ppm) or parts per billion (ppb). A solution that contains 2 grams(0.071 ounces) of lead in 1 million grams (2,205 pounds) of water (1,000 liters, or 264.2 gallons) is a 2 ppm solution. A 1 ppb solution of calcium contains 1 gram (0.036 ounces) of calcium in 1 billion grams (2,205,000 pounds) of water. A concentration of 1 ppm is the same as 1 milligram(3.6 × 10−5 ounces) per liter.
While it is impractical to remove all impurities from water, the Safe Drinking Water Act, passed by the U.S. Congress in 1974, gives the Environmental Protection Agency (EPA) the authority to set limits for harmful contaminants in water. For each substance, the EPA establishes Maximum Contaminant Level Goals (MCLGs), levels at which the substance can be consumed over a long period of time with no known adverse effects. This level is defined as the amount of impurity that could be present in two liters of water drunk by a person weighing 70 kilograms (154 pounds), each day for seventy years, without ill effects. In addition, the EPA sets Maximum Contaminant Levels (MCLs) of substances for exposure at any single time. A single exposure to concentrations of pollutants below the MCL is considered to be harmless. The MCLG of lead is 0; continuous exposure to lead in any concentration is considered hazardous. The MCL of lead is 0.015 ppm. Both the MCLG and MCL of mercury are set at 0.002 ppm.
Specialized analytical equipment allows technicians to monitor pollutants. In the field, pH meters are used to measure acidity and turbidometers measure the presence of suspended solids. Samples taken to laboratories are analyzed by gas chromatography to determine the presence of organic
compounds such as vinyl chloride, by emission spectroscopy to detect heavy metals , and by high performance liquid chromatography (HPLC) to detect pesticide residues. Such instruments are capable of detecting as little as one part per trillion of pollutants in water.
For much of history, humans used waterways and bodies of water as waste dumps. When the human population was low, fewer people were exposed to the effects of pollution, and the sources were fewer and produced less pollution. During the Industrial Revolution of the nineteenth century, water pollution was recognized as a danger to public health.
Even early settlers were concerned with water quality. Two hundred years before laws were written to protect consumers from lead poisoning, Benjamin Franklin wrote of a family that suffered gastrointestinal pains after drinking water collected from their lead roof. During the trek west, members of wagon trains avoided drinking from stagnant pools, some of which contained large amounts of alkali.
As populations and production grew, industrial and household refuse accumulated, and it became clear that many discarded materials did not simply disappear, but were spread through the water table, absorbed by lower forms of life and passed up the food chain, causing deaths, birth defects, and mental problems. Now, many beaches are closed occasionally or permanently due to pollution, and at a time when populations of fish have decreased, many areas are unsafe for fishing. Water pollution represents an especially dangerous problem in developing nations, which have high populations and manufacturing facilities that do not meet safety standards.
The most dangerous forms of water pollutants include sewage, which frequently contains dangerous pathogenic organisms; oil and hydrocarbons; heavy metals; radioactive substances; pesticides and herbicides; and corrosive substances such as acids and bases.
In developed countries, few direct sources of water pollution should exist, but homeowners still discharge motor oil, antifreeze, pet waste, and paint into storm sewers, and small manufacturers sometimes ignore proper disposal procedures. In developing countries, businesses and households often discharge wastes directly into streams or ponds that are also used for water supplies. Many sources contaminate water supplies indirectly. Indirect sources of pollution include runoff of waste from feedlots or runoff of agricultural chemicals from farmlands; leaking oil from pipelines, wells, or platforms; and large amounts of sediment from streets and parking lots.
Most industrial operations are required to treat wastewater before discharging it into rivers. Wastes from feedlots are collected in lagoons, settled, collected, and used for fertilizer. Heavy metals and organic compounds from industry are often reclaimed from wastewater and recycled, decreasing manufacturing costs. Sewage from homes undergoes at least two stages of treatment. Primary treatment consists of sedimentation and dyeing of solids, which may be used as fertilizer. Secondary treatment consists of aeration of the remaining liquid, through a process of stirring, trickling over filters, and spraying; aerobic bacteria oxidize much of the remaining organic matter. Tertiary treatment, using antibacterial agents such as chlorine or ozone, may be used to produce effluent water that is safe for further use.
see also Neurotoxins; Toxicity; Water; Water Quality.
Dan M. Sullivan
Stanitski, Conrad L.; Eubanks, Lucy P.; Middlecamp, Catherine H.; and Pienta, Norman J. (2003). Chemistry in Context: Applying Chemistry to Society, 4th edition. Boston: McGraw-Hill.
Any physical, biological, or chemical change in water quality that adversely affects living organisms or makes water unsuitable for desired uses can be considered pollution.
Often, however, a change that adversely affects one organism may be advantageous to another. Conversely, antibiotics designed for use at one site, might pose a pollution threat to non-target or beneficial downstream microorganisms and ultimately other life forms.
The U.S. Environmental Protection Agency (EPA) oversees National Primary Drinking Water Regulations (NPDWRs or primary standards), which are legally enforceable standards regarding water contained in public water systems. Primary standards are intended to promote and protect public health by setting limits for levels of contaminants in drinking water. Agents of pollution or contaminants are divided into categories of microorganisms, disinfectants, disinfection byproducts, organic chemicals, inorganic chemicals, and radionuclides.
Nutrients that stimulate growth of bacteria and other oxygen-consuming decomposers in a river or lake, for example, are good for the bacteria but can be lethal to game fish populations. Similarly, warming of waters by industrial discharges may be deadly for some species but may create optimal conditions for others. Whether the quality of the water has suffered depends on your perspective. There are natural sources of water contamination, such as arsenic springs, oil seeps, and sedimentation from desert erosion, but most environmental scientists restrict their focus on water pollution to factors caused by human actions and that detract from conditions and uses that humans consider desirable.
Water pollution control regulations usually distinguish between point and non-point pollution sources. Factories, power plants, sewage treatment facilities, underground mines and oil wells, for example, are classified as point sources because they release pollution from specific locations, such as drain pipes, ditches, or sewer outfalls. These individual, easily identifiable sources are relatively easy to monitor and regulate. Their unwanted contents can be diverted and treated before discharge. In contrast, non-point pollution sources are scattered or diffuse, having no specific location where they originate or discharge into water bodies. Some non-point sources include runoff from farm fields, feedlots, lawns, gardens, golf courses, construction sites, logging areas, roads, streets, and parking lots. Whereas point sources often are fairly uniform and predictable, non-point runoff often is highly irregular. The first heavy rainfall after a dry period, for example, may flush high concentrations of oil, gasoline, rubber, and trash off city streets, while subsequent runoff may have much lower levels of these contaminants. The irregular timing of these events, as well as their multiple sources, scattered location, and lack of specific ownership make them much more difficult to monitor, regulate, and treat than point sources.
Among the most important categories of water pollutants are sediment, infectious agents, toxins, oxygen demanding wastes, plant nutrients, and thermal changes. Sediment (dirt, soil, insoluble solids) and trash make up the largest volume and most visible type of water pollution in most rivers and lakes. Rivers have always carried silt, sand, and gravel down to the oceans but human-caused erosion now probably rivals the effects of geologic forces. Worldwide, erosion from croplands, forests, grazing lands, and construction sites is estimated to add some 75 billion tons of sediment each year to rivers and lakes. This sediment smothers gravel beds in which fish lay their eggs. It fills lakes and reservoirs, obstructs shipping channels, clogs hydroelectric turbines, and makes drinking water purification more costly. The most serious water pollutant in terms of human health worldwide is pathogenic (disease-causing) organisms. Among the most deadly waterborne diseases are cholera, dysentery, polio, infectious hepatitis, and schistosomiasis. Together, these diseases probably cause at least two billion new cases of disease each year and kill somewhere between six and eight million people. The largest source of infectious agents in water is untreated or insufficiently treated human and animal waste. The United Nations estimates that more than one-half of the world’s population has inadequate sanitation and that over one billion people lack access to clean drinking water. Water pollution has been accused of being the leading cause of death and disease in the world.
Toxins are poisonous chemicals that interfere with basic cellular metabolism (the enzyme reactions that make life possible). Among some important toxins found in water are metals (lead, mercury, cadmium, nickel), inorganic elements (selenium, arsenic), acids, salts, and organic chemicals such as pesticides, solvents, and industrial wastes. Some of these materials are so toxic that exposure to extremely low levels (perhaps even parts per billion) can be dangerous. Others, while not usually found in toxic concentrations in most water bodies, can be taken up by living organisms, altered into more toxic forms, stored, and concentrated to dangerous levels through food chains. For example, fish in lakes and rivers in many parts of the United States have accumulated mercury (released mainly by power plants, waste disposal, and industrial processes) to levels that are considered a threat to human health for some people with certain health problems or women that are pregnant who eat fish on a regular basis.
The United States continues to work toward a goal of making all surface waters fishable and swimmable. Investments in sewage treatment, regulation of toxic waste disposal and factory effluents, and other forms of pollution control have resulted in significant water quality increases many areas. Nearly 90% of all the river miles and lake acres that are assessed for water quality in the United States fully or partly support their designed uses. Lake Erie, for instance, which was widely described in the 1970s as being “dead,” now has much cleaner water and more healthy fish populations than would ever have been thought possible 30 years ago. Unfortunately, surface waters in developing countries have not experienced similar progress in pollution control. In most developing countries, only a tiny fraction of human wastes are treated before being dumped into rivers, lakes, or the ocean. In consequence, water pollution levels often are appalling. In India, for example, two-thirds of all surface waters are considered dangerous to human health.
In 1972, the United States enacted federal legislation called the Federal Water Pollution Control Act Amendments in order to control water pollution. In 1977, further amendments were added, and the Act became known as the Clean Water Act (CWA), which is the primary federal law to control water pollution. It made the Environmental Protection Agency (EPA) the authority in establishing water quality standards across the country. In 2002, the Act was further modified to include the Great Lakes Legacy Act, which deals with contaminated sediments on the bottom of the Great Lakes.
See also Waste, toxic.
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.
Outwater, Alice. Water: A Natural History. New York: Basic Books, 1996.