Quick Links
- 2018 version of CWA from the U.S. Code (233 pp, 1.23 MB)
- The official text of the CWA continues to be available in the United States Code from the US Government Printing Office
33 U.S.C. §1251 et seq. (1972)
The Clean Water Act (CWA) establishes the basic structure for regulating discharges of pollutants into the waters of the United States and regulating quality standards for surface waters. The basis of the CWA was enacted in 1948 and was called the Federal Water Pollution Control Act, but the Act was significantly reorganized and expanded in 1972. "Clean Water Act" became the Act's common name with amendments in 1972.
Under the CWA, EPA has implemented pollution control programs such as setting wastewater standards for industry. EPA has also developed national water quality criteria recommendations for pollutants in surface waters.
The CWA made it unlawful to discharge any pollutant from a point source into navigable waters, unless a permit was obtained:
- EPA's National Pollutant Discharge Elimination System (NPDES) permit program controls discharges.
- Point sources
are discrete conveyances such as pipes or man-made ditches.
- Individual homes that are connected to a municipal system, use a septic system, or do not have a surface discharge do not need a NPDES permit;
- Industrial, municipal, and other facilities must obtain permits if their discharges go directly to surface waters.
Compliance and Enforcement
- Clean Water Act Compliance Monitoring: investigations and inspections
- Water Enforcement
History of this Act
- EPA History: Federal Water Pollution Control Act Amendments of 1972
- History of the Clean Water Act
- Archived EPA History: Clean Water Act
More Information
The Office of Water (OW) ensures drinking water is safe, and restores and maintains oceans, watersheds, and their aquatic ecosystems to protect human health, support economic and recreational activities, and provide healthy habitat for fish, plants, and wildlife.
- The EPA Watershed Academy provides training courses on statutes, watershed protection, and other key Clean Water Act resources.
All AP Environmental Science Resources
Which of the following is not a type of water pollution?
Possible Answers:
Nutrient pollution
All of these are types of water pollution
Sediment pollution
Toxic chemical pollution
Diseases and pathogen pollution
Correct answer:
All of these are types of water pollution
Explanation:
Water can be polluted and unusable due to the presence of toxic chemicals, sediments, nutrient pollution, diseases and/or pathogens, as well as thermal pollution.
Which of the following is a secondary air pollutant?
Possible Answers:
Carbon monoxide
Nitric oxide
Tropospheric ozone
Sulfur dioxide
Correct answer:
Tropospheric ozone
Explanation:
A secondary pollutant is any kind of pollutant that is not directly emitted form a pollution source. In this case, sulfur dioxide, carbon monoxide and nitric oxide are all emitted from the burning of fossil fuels, especially coal. Tropospheric ozone is formed in the reaction between volatile organic compounds and nitrous oxides and is a component in photochemical smog.
Water pollutants originate from both natural and human-made causes and they are classified into two general types.
Name the two types of sources of water pollution?
Possible Answers:
Agriculture and municipal
Anthropogenic and ecological
Chemical and biological
Industrial and nonindustrial
Point source pollution and nonpoint source pollution
Correct answer:
Point source pollution and nonpoint source pollution
Explanation:
Point source pollution can be traced to a specific source. Factory waste is a good example. Nonpoint source pollution cannot be traced to a single source. Agricultural runoff and storm sewers are good examples.
One of the negative effects of air pollution is that it can cause problems in the ozone layer. Which class of chemicals are known to deplete ozone?
Possible Answers:
Methane
Chlorofluorocarbons (CFCs)
Sulfur dioxide
Carbon dioxide
Correct answer:
Chlorofluorocarbons (CFCs)
Explanation:
The correct response is chlorofluorocarbons (CFCs). These chemical compounds are known to deplete ozone from the atmosphere. During the 1960s and 1970s, refrigerators were manufactured with CFCs. This is what created the whole in the ozone which we have all heard about. The Environmental Protection Agency banned the use of CFCs and this is greatly improved the quality of ozone in the atmosphere.
One of the big contributors to water pollution in the Great Lakes is eutrophication. Which of the following is least likely to cause eutrophication?
Possible Answers:
Wetland habitat
Stormwater runoff
Agricultural runoff
Lawn fertilizers
Correct answer:
Wetland habitat
Explanation:
The correct response is wetland habitat. Wetlands help filter out nutrients and actually help prevent eutrophication. Eutrophication is the process by which nutrients accumulate in a body of water. For example, big storm events cause nutrients to leach off the ground and into rivers and lakes via runoff. All of the other answer choices either increase the rate of runoff (i.e. urbanization) or increase the amount of nutrients leaching (i.e. fertilizers).
Many times eutrophication creates dead zones or hypoxic zones in bodies of water. The most famous dead zone in North America occurs where the Mississippi River outflows into the Gulf of Mexico. What important resource do dead zones not have?
Possible Answers:
Potassium
Nitrogen
Oxygen
Carbon dioxide
Explanation:
The correct response is oxygen. Deadzone are completely depleted of oxygen. This can be due to algal blooms - which consume all the available oxygen in the system. Once all the oxygen is depleted, the algae die and fall to the bottom of the lake or ocean. Deadzones can be harmful for many aquatic organisms, especially fish and bottom feeders.
Pollution is one of the major environmental issues affecting humans today. Urbanization has create the heat island effect. What type of pollution are heat islands?
Possible Answers:
Thermal pollution
Water pollution
Chemical pollution
Noise pollution
Correct answer:
Thermal pollution
Explanation:
The correct response is thermal pollution. The heat island effect occurs in urban cities that have a lot of black top and impervious surfaces. Heat gets trapped in the cities because there aren't many trees or natural vegetation to absorb sunlight and respire. Studies have shown that temperatures in downtown regions are significantly higher than temperatures in the suburbs of major US cities. Thus, heat islands cause there to be an excess of heat and we call this thermal pollution.
Water-soluble inorganic materials cause algal blooms which die and create oxygen deficiencies, killing fish. Which is not a water-soluble inorganic metarial?
Possible Answers:
All of these are water-soluble inorganic pollutants
Caltrates
Nitrates
Phosphates
Explanation:
You may have associated "caltrates" with calcium, which is a heavy metal pollutant and is not water soluble. Nitrates and phosphates are not inherently toxic, however, when present in large quantities, can throw off the balance of an ecosystem to disastrous consequences.
All of the following may be natural sources of pollution except __________.
Possible Answers:
acid mine drainage
oil seeps
forest fires
volcanic eruptions
cows expelling methane
Correct answer:
acid mine drainage
Explanation:
Acid mine drainage occurs when water seeps through a mine or a mine’s waste pile and results in a solution of sulfuric acid. Water is used to process ore and it can become contaminated with sulfuric acid, mercury and arsenic. The contaminated water can damage ecosystems and is particularly harmful to aquatic life. Some acid drainage can occur naturally when water interacts with rock but the degree of contamination is significantly different.
Which of the following is considered a nonpoint source of pollution?
Possible Answers:
Fertilizers and pesticides in runoff
Water pollution from mine tailings
A leaky underground storage tank
Automobile exhaust pipe
A factory smoke stack
Correct answer:
Fertilizers and pesticides in runoff
Explanation:
It is common to find some amount of fertilizers and pesticides in runoff water. It is difficult to determine the source of this pollution. Runoff may travel over many plots of lands including farms, golf courses, home gardens, etc. So there may even be multiple sources.