Chapter 20 -- Water Pollution
After studying this chapter, you should be able to:
  • define water pollution and describe the sources and effects of some major types.

  • appreciate why access to sewage treatment and clean water are important to people in developing countries.

  • discuss the status of water quality in developed and developing countries.

  • delve into groundwater problems and suggest ways to protect this precious resource.

  • fathom the causes and consequences of ocean pollution.
  • weigh the advantages and disadvantages of different human waste disposal techniques.

  • judge the impact of water pollution legislation and differentiate between best available and best practical technology, and total maximum daily pollution loads.


What is Water Pollution?

Types and Effects of Water Pollution

Infectious Agents

Table 20.1 -- Major categories of water pollutants
A. Causes health problems
1. Infectious agents
Bacteria, viruses, parasites
Human and animal excreta
2. Organic chemicals
Pesticides, plastics, detergents, oil, and gasoline
Industrial, household, and farm use
3. Inorganic chemicals
Acids, caustics, salts, metals
Industrial effluents, household cleansers, surface runoff.
4. Radioactive materials
Uranium, thorium, cesium, iodine, radon
Mining and processing of ores, power plants, weapons production, natural sources
B. Causes ecosystem disruption
1. Sediment
Soil, silt
Land erosion
2. Plant nutrients
Nitrates, phosphates, ammonium
Agricultural and urban fertilizers, sewage, manure
3. Oxygen-demanding wastes
Animal manure and plant residues
Sewage, agricultural runoff, paper mills, food processing
4. Thermal
Power plants, industrial cooling

Oxygen-Demanding Wastes

Plant Nutrients and Cultural Eutrophication

Toxic Tides

Inorganic Pollutants

Organic Chemicals


Thermal Pollution and Thermal Shocks

Water Quality Today

Surface Waters in the United States and Canada

Surface Waters in Other Countries

Groundwater and Drinking Water Supplies

  • In addition to groundwater pollution problems, contaminated surface waters and inadequate treatment make drinking water unsafe in many areas.

  • Every year epidemiologists estimate that around 1.5 million Americans fall ill from infections caused by fecal contamination.

Ocean Pollution

Water Pollution Control

Source Reduction

  • The cheapest and most effective way to reduce pollution is to avoid producing it or releasing it to the environment in the first place.

  • Industry can modify manufacturing processes so fewer wastes are created.

  • Recycling or reclaiming materials that otherwise might be discarded in the waste stream also reduces pollution.

Nonpoint Sources and Land Management

Human Waste Disposal

Water Remediation

Water Legislation

Table 20.2 -- Some important U.S. water quality legislation
  1. Federal Water Pollution Control Act (1972). Established uniform nationwide controls for each category of major polluting industries.

  2. Marine Protection Research and Sanctuaries Act (1972). Regulates ocean dumping and established sanctuaries for protection of endangered marine species.

  3. Ports and Waterways Safety Act (1972). Regulates oil transport and the operation of oil handling facilities.

  4. Safe Drinking Water Act (1974). Requires minimum safety standards for every community water supply. Among the contaminants regulated are bacteria, nitrates, arsenic, barium, cadmium, chromium, fluoride, lead, mercury, silver, pesticides; radioactivity and turbidity also regulated. This act also contains provisions to protect groundwater aquifers.

  5. Resource Conservation and Recovery Act (RCRA)(1976). Regulates the storage, shipping, processing, and disposal of hazardous wastes and sets limits on the sewering of toxic chemicals.

  6. Toxic Substances Control Act (TOSCA) (1976). Categorizes toxic and hazardous substances, establishes a research program, and regulates the use and disposal of poisonous chemicals.

  7. Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) (1980) and Superfund Amendments and Reauthorization Act (SARA) (1984). Provide for sealing, excavation, or remediation of toxic and hazardous waste dumps.

  8. Clean Water Act (1985) (amending the 1972 Water Pollution Control Act). Sets as a national goal the attainment of "fishable and swimmable" quality for all surface waters in the United States.

  9. London Dumping Convention (1990). Calls for an end to all ocean dumping of industrial wastes, tank washing effluents, and plastic trash. The United States is a signatory to this international convention.

The Clean Water Act

Clean Water Act Reauthorization

Other Important Water Legislation

  • In addition to the Clean Water Act, several other laws help to regulate water quality in the United States and abroad.

    • Safe Drinking Water Act.

    • "Superfund Program" -- Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) as amended by the Superfund Amendments and Reauthorization Act (SARA).

    • Great Lakes Water Quality Agreement (U.S. and Canada)


Questions for Review

  1. Define water pollution.
  2. List eight major categories of water pollutants and give an example for each category.
  3. Describe eight major sources of water pollution in the United States. What pollution problems are associated with each source?
  4. What is Pfiesteria and why is it dangerous?
  5. What is eutrophication? What causes it?
  6. What are the origins and effects of siltation?
  7. Describe primary, secondary, and tertiary processes for sewage treatment. What is the quality of the effluent from each of these processes?
  8. Why do combined storm and sanitary sewers cause water quality problems? Why does separating them also cause problems?
  9. What pollutants are regulated by the Clean Water Act? What goals does this act set for abatement technology?
  10. Describe remediation techniques and how they work.

Questions for Critical Thinking

  1. How precise is the estimate that 2 billion people lack access to clean water? Would it make a difference if the estimate is off by 10 percent or 50 percent?
  2. How would you define adequate sanitation? Think of some situations in which people might have different definitions for this term.
  3. Do you think that water pollution is worse now than it was in the past? What considerations go into a judgment like this? How do your personal experiences influence your opinion?
  4. What additional information would you need to make a judgment about whether conditions are getting better or worse? How would you weigh different sources, types, and effects of water pollution?
  5. Imagine yourself in a developing country with a severe shortage of clean water. What would you miss most if your water supply were suddenly cut by 90 percent?
  6. Why has EPA changed to total maximum daily pollution loads and watershed management? What are the major implications of this change?
  7. Proponents of deep well injection of hazardous wastes argue that it will probably never be economically feasible to pump water out of aquifers more than 1 kilometer below the surface. Therefore, they say, we might as well use those aquifers for hazardous waste storage. Do you agree? Why or why not?
  8. Under what conditions might sediment in water or cultural eutrophication be beneficial? How should we balance positive and negative effects?
  9. Suppose that part of the silt in a river is natural and part is human-caused. Is one pollution but the other not?
  10. Suppose that you own a lake but it is very polluted. An engineer offers options for various levels of cleanup. As you increase water quality, you also increase costs greatly. How clean would you want the water to be--fishable, swimmable, drinkable--and how much would you be willing to pay to achieve your goal? Make up your own numbers. The point is to examine your priorities and values.