The Big Picture

By the 1960's, water pollution had become a major environmental and human health issue in many urban as well as rural areas of the United States. As a result of the near biological death of such places as Lake Erie and the Hudson River, citizens and legislators responded by promoting and enacting federal and state legislation aimed at reducing pollution inputs and cleaning up existing water pollution problems. Agencies have now been established to measure and monitor water quality to ensure that drinking water and water in streams, rivers, and estuaries meets basic standards for water quality. If waters are found to be out of compliance with these standards, legal actions may be undertaken to remediate the problems. Water quality parameters that are routinely monitored include biological oxygen demand (BOD), dissolved oxygen concentrations (DO), coliform bacteria, nutrient concentrations, oils, sediments, and an array of hazardous and toxic chemicals. Pollutants may enter waterways as from specific locations called point sources, such as wastewater discharge pipes, or from diffuse locations, called nonpoint sources, such as agricultural and urban runoff. As a consequence of public involvement, legislation, and the application of new technologies to manage and treat wastewater, many areas that were severely polluted decades ago are now much improved. However, as human populations increase and relocate to new regions of the country water pollution problems often accompany these changes. In addition, new and complex toxic chemicals are being introduced into the environment and ultimately into water from industry, agriculture, runoff, and air pollution. Worldwide, water pollution and water borne diseases are enormous environmental and human health problems; from densely populated India where fecal coliform bacteria concentrations are measured in millions of cells per 100 ml to the seemingly pristine lakes of central Canada where fish are contaminated with mercury.

Frequently Asked Questions

• Water pollution is the degradation of physical, chemical, or biological properties of water, beyond normal conditions. These properties comprise water quality.
• Water quality determines how water can be used. For example, if water is to be used as a supply of drinking water, it must be free of toxic chemicals and pathogens that cannot be removed through normal treatment processes. However, water that contains toxic chemicals and pathogens may be suitable for industrial processing.
• Water pollution may originate from any sector of society: urban, rural, industrial, agricultural, and military (Table 20.1 and Table 20.2).

• In the United States, the Environmental Protection Agency (EPA) has established sets of water quality standards (threshold concentrations or conditions) for several common pollutants (Table 20.3). If these standards are exceeded, water may not be legally used for certain purposes. States must adopt these standards or develop more stringent standards. Standards differ according to water classification; drinking water standards are more stringent than standards for water in streams and rivers.
• Water quality monitoring (systematically sampling and analyzing water or wastewater) is usually accomplished by state environmental agencies. The EPA maintains a national database (STORET) of water quality data.
• A federal program to assess and monitor the nation's water quality is the National Water Quality Assessment (NAWQA) program, which attempts to standardize sampling regimes and techniques, and data analysis in major watersheds throughout the United States.

• BOD and DO are not pollutants, but are critical aspects of water quality. The decomposing organic remains of aquatic plants and animals, or organic debris that is carried into waterways by natural processes (e.g., wind, runoff, flooding) forms the basis for decomposer food chains. However, excessive organic matter may also be a pollutant.
• Microbes utilize oxygen in decomposition processes. Oxygen usage can be measured and reported as BOD. Excessive organic matter and high decomposition rates may reduce the concentration of dissolved oxygen. As BOD increases, DO typically decreases.
• Species of fish and invertebrates that are intolerant of abnormally low dissolved oxygen concentrations cannot survive, and are replaced by more tolerant species.
• Sources of excessive organic matter include improperly functioning sewage treatment facilities, livestock operations, urban runoff, as well as the decomposing remains of algae and aquatic plants resulting from eutrophication.
• In flowing waters, water quality gradually improves downstream from the polluted site (Figure 20.2). Initially, there exists a polluted zone characterized by high BOD and reduced DO. Further downstream, in the active decomposition zone, microbial decomposition is at a maximum and DO is minimum. In the recovery zone, most of the organic matter has been consumed, microbial decomposition and BOD are reduced, and DO concentrations recover.
• Dissolved oxygen concentrations are also closely coupled with water temperature and movement. DO concentrations tend to be highest in cold and turbulent waters with low BOD. Conversely, warm, still waters with high BOD tend to have low DO concentrations.

• Waterborne diseases are responsible for the illness or death of millions of humans each year. Amoebic dysentery and cholera are a few of the pathogenic diseases than may be contracted from contaminated drinking water.
• In the more developed nations, drinking water supplies usually receive sufficient treatment to eliminate most pathogens. In the less developed nations, treatment of drinking water supplies is often inadequate and disease transmission is much more common.
• Because it is difficult to monitor water for specific pathogens, fecal coliform bacteria are used as indicators of potential water contamination. Fecal coliform bacteria reside in the gut of endotherms ("warm-blooded" animals, including humans); thus the presence of fecal coliform in water samples indicates the potential for pathogens to exist.
• The EPA has established standards for fecal coliform concentrations. Based on fecal coliform concentrations, waters are suitable for full contact activities (swimming and wading) if fecal coliform concentrations are less than 200 colonies/100 ml. Waters suitable for drinking may not contain any coliform bacteria, after treatment.

• Nitrogen and phosphorus are essential plant nutrients. In aquatic, estuarine, and marine ecosystems, the concentrations of these two nutrients may impose limitations on plant growth. In excessive quantities, nitrogen and phosphorous may stimulate the production of phytoplankton, filamentous algae, and aquatic macrophytes (submerged, floating, and emergent higher plants). This process called is eutrophication and usually results in a decline in water quality (Figure 20.5).
• Eutrophic waters are characterized by excessive nutrient input and subsequently increased plant production. Oligotrophic waters are nutrient poor.
• Nutrients enter waterways via runoff from agricultural fields, livestock operations, wastewater treatment facilities, as well as, residential, urban, and industrial areas and golf courses.
• Nitrogen and phosphorus concentrations tend to be highest in regions where agriculture is the primary land use (Figure 20.3).
• Nitrogen, in the nitrate form, may cause human health problems if it infiltrates into drinking well water supplies. In some rural areas in the vicinity of intensive livestock operations, nitrate contamination has become a problem.

• Oil (i.e., crude oil, heating fuel, gasoline) is a water pollutant. Major oil spills capture news headlines and cause severe environmental degradation and risks to human health in localized areas (Figure 20.7).
• The immediate and most obvious effects of oil spills on the environment are the deaths of shellfish, finfish, shorebirds, waterfowl, and marine or aquatic mammals.
• After the spill has dissipated and clean-up efforts have been undertaken, the long-term effects of oil contamination may persist. Oil may persist in sediments and substrates, possibly disrupting food chains and damaging spawning and nursery areas for many years.
• The effects of oil spills are variable, dependent upon the characteristics of the oil (viscosity, degree of refinement, presence of toxic chemicals in the oil) and the physical conditions of the water (temperature, motion, depth).
• Areas that are most susceptible to oil spills are shipping terminals and routes, waters adjacent to refineries, and marinas.
• While oil spills are especially newsworthy, the daily and cumulative discharge of oil from boat motors, runoff from roadways, leaking storage tanks, and other relatively small discharges cause more widespread contamination (Fig. 20.1).

• By volume and mass, sediments (rock and mineral fragments, chiefly: sand, silt, clay).
• Two environmental problems stem from sediment pollution. Firstly, soil loss reduces the long-term soil productivity. Secondly, eroded sediment enter water ways thus degrading water quality and filling streambeds, channels, lake bottoms, and harbors with sediment.
• Erosion and sedimentation problems are closely coupled with land use patterns. Cultivated cropland or areas denuded by intensive grazing or feedlots may have significant erosion problems. This is especially problematic in areas with sloping topography and high rainfall, or where soil conservation practices are not utilized.
• By contrast, permanent vegetative cover (i.e., forest or pasture) greatly reduces erosional losses. In general, water quality is much higher in watersheds dominated by forests compared to those dominated by agricultural production.
• Sedimentation emanates from urban areas as well. The construction of buildings and roadways may result in severe erosion, albeit most severe during the construction phase. Once the buildings or roads are completed, a vegetative cover may reduce but not eliminate erosion and sedimentation problems.
• Impervious surfaces, such as rooftops, paved parking lots and roads, concentrate the erosive force of water by diverting high volumes of runoff into small receiving areas.

• Mining activities may result in the acidification of streams and other surface waters and groundwaters due to acid mine drainage.
• As surface runoff and groundwater moves through mined areas or mine tailings, sulfuric acid is leached into these waters lowering the pH to levels that may be toxic to most organisms.
• Streams in the coal mining regions of the Appalachian Mountains, Allegheny Plateau, and Rocky Mountains are especially polluted due to acid mine drainage. Copper, lead, zinc or other mines that liberate sulfuric acid as a by-product, are also sources of acid mine drainage.

• Discharges of pollution from distinct and confined locations are considered point sources of pollution. For example, sewage or industrial waste discharges from pipes into waterways.
• Pollutant sources that are more diffuse and less confined than point sources are called nonpoint sources. For example, runoff from roadways and parking lots, lawns and other urban areas, agricultural fields and feedlots, mine sites, and some forest sites.

• Point sources are more readily monitored, regulated, and controlled than nonpoint sources. One way that point source pollution is being reduced is through a federally- mandated permit system. In order for a factory, municipal wastewater facility, or other wastewater discharger to discharge into waterways, a NPDES (National Pollutant Discharge Elimination System) permit must be obtained. This program helps to ensure that pollutants in wastewater discharges do not exceed EPA standards.
• In general, there has been considerable improvement in water quality in the United States since the 1950's and 1960's. This has come about largely as a result of federal and state legislation and enforcement aimed at reducing point sources of pollutant discharges and implementing appropriate technologies.
• Nonpoint sources of pollution are much more difficult to regulate and treat. Federal and state environmental agencies have long recognized the problems associated with nonpoint source pollution, but the implementation of regulations and technologies is only now being attempted.
• Nonpoint source pollution is closely coupled with land use. Therefore, planning and implementing appropriate land use practices can reduce this type of pollution. This may entail such practices as: establishing permanent vegetative buffers between agricultural areas and waterways, maintaining highly erodable slopes in a vegetative cover, and creating catchment basins or artificial wetlands to collect and treat runoff.
• Perhaps more expensive and difficult to implement is the treatment of wastewater containing nonpoint source pollutants in wastewater treatment facilities. Many large municipalities will soon be required to treat urban runoff in a wastewater treatment facility before discharging to natural waters.
• Ecologists, planners, and many citizens are aware that if water quality is to be improved and maintained at a high level, water pollution issues will have to be addressed on a regional or watershed basis. State and federal agencies are developing and implementing watershed-water quality plans for many regions of the United States.

• Groundwater pollution is not widespread in the United States, but many local areas are experiencing problems with contamination. Approximately one-half of all people in the United States rely on groundwater for all or part of their drinking water supply, so it is vital to protect groundwater from contamination.
• Groundwater contamination often results from abandoned, illegal, or improperly functioning waste disposal sites. Leachate (contaminated water) infiltrates into groundwater supplies and moves in plumes through the aquifer.
• Leaking underground storage tanks (e.g., buried heating oil tanks at houses and gasoline tanks at gas stations) constitute a significant problem in the United States. Not only is there a risk of groundwater contamination but, the corrosive effects of petroleum could damage buried cables, water lines, and sewer lines.
• In the United States, an estimated 75% of the 175,000 known waste disposal sites may be producing plumes of hazardous chemicals that could migrate into groundwater.
• In some agricultural areas, pesticides and fertilizer may contaminate groundwater.
• In coastal areas, excessive groundwater withdrawals may lead to saltwater intrusion into freshwater aquifers, thus contaminating the water supply (Figure 20.11).
• The hazards presented by a specific contamination site depend upon the concentration and toxicity of the contaminants, exposure risk to humans and other organisms, as well as, local geology and hydrology which affects dispersal capability of the contaminants.

• In most rural areas, there are no centralized wastewater treatment facilities. Most homes rely upon on-site, septic-tank disposal systems to treat domestic sewage. The effectiveness of septic-tank systems depends upon proper siting and maintenance.
• Septic-tanks function by separating solids from liquids, creating an environment that facilitates decomposition by microbes, stores organic matter, and clarifies liquids to be discharged. Once discharged into an absorption field, the treated wastewater is oxidized and filtered (Figure 20.13).
• In urban and industrial areas, wastewater is usually treated at centralized wastewater treatment facilities. Liquefied raw sewage is transported to a treatment facility via a network of sewer pipes. Treated wastewater is then discharged into receiving waters (river, lake, or ocean) or used for crop irrigation. The Federal Water Pollution Control Act, and amendments (Clean Water Act) stipulates that wastewater must be treated before it is discharged into natural waters.
• There are three categories of wastewater treatment methods: primary treatment, secondary treatment, and advanced (or tertiary) treatment (Figure 20.14).
• Primary treatment entails separating particulate matter (sand, grit, plastic, paper), grease and oils from incoming sewage. In settling tanks, the application of alum or similar chemicals to facilitate the precipitation of sludge, which will be collected and treated. Primary treatment reduces the pollutant volume of wastewater by 30% to 40%. In most municipalities, primary treatment is only the first step in wastewater treatment, to be followed by secondary treatment.
• Secondary treatment utilizes activated sludge (which contains aerobic microbes) to decompose the organic sewage received from primary treatment. In aeration tanks, wastewater is mixed and kept aerated to promote decomposition. Next, the wastewater is transferred to sedimentation tanks where anaerobic microbes further degrade the accumulated sludge. Methane gas is a by-product. Finally, the wastewater is treated with chlorine (or other disinfectants) to kill bacteria or pathogens. The treated wastewater is then discharged into receiving waters or, in limited cases, used for irrigation. After secondary treatment, approximately 90% of the original pollutant volume is removed.
• Advanced treatment entails using additional treatment steps to remove pollutants that still remain in wastewater after secondary treatment. These pollutants typically include nutrients (phosphate and nitrates), organic chemicals, and heavy metals. Specific technologies must be used to remove these pollutants; these technologies may be very expensive, but the expense may be necessary if the receiving waters are especially sensitive.

• Treated wastewater can be recycled but precautions must be taken to avoid the transmission of pathogen or contaminants.
• Under the proper site and usage conditions, treated wastewater may be used to irrigate crops, lawn, and golf courses, and to recharge aquifers.
• Wetlands have been used to receive discharged wastewater, though this is largely experimental. Wetland plants are capable of absorbing excessive nutrients and contaminants, thus removing them from water supplies. The widespread use of natural wetlands for wastewater recycling is unlikely, however, the use of artificially constructed wetland may be more promising.

• In the United States, drinking water is obtained from groundwater and surface water supplies. Some groundwater is of high quality and may not need treatment prior to consumption. However, most surface water requires treatment to remove pathogens or other contaminants.
• Chlorination is a widely used method to eliminate most pathogens, however, the chlorine added to water may result in adverse taste or may present a health risk itself.
• Federal and state drinking water standards are designed to keep contaminant concentrations to a minimum. However, health complications arising from long-term exposure to low levels of contamination are poorly understood.

• The Federal Water Pollution Control Act (commonly referred to as the Clean Water Act) is the most comprehensive legislation targeting water pollution control. This Act includes important legislation such as requiring permits to discharge wastewater into waterways (NPDES permits) and legislation that wetland provide protection for the nation's wetlands (Sections 404 and 401).
• The Safe Drinking Water Act empowers the EPA to establish drinking water standards.
• The Water Quality Act targets nonpoint source pollution.
• See Table 20.4 for information on other water pollution legislation.

Ecology In Your Backyard

• Do you know the source of your drinking water? Clean water is absolutely basic to good health, however too often we do not know the source of our water or the fate of our wastewater.
• Arrange a visit to the water treatment facility and the wastewater treatment facility nearest you. Often, tours can be arranged to provide you with an overview of facility operation and laboratories.
• Contact your state fish and game or wildlife office to find out if advisories have been issued to limit or avoid human consumption of fish taken from local waters. Long-lived fish, bottom-feeding fish, or species at the top of aquatic food chain tend to bioaccumulate toxins.
• Please respond to these questions or send your thoughtful examples and comments to:

Hardcopy Links In The Library

• Stednick, J.D. Wildland Water Quality Sampling and Analysis. 1991. San Diego: Academic Press, Inc. A concise review of general chemistry and water quality sampling techniques and standard procedures is presented prior to a discussion of typically measured water quality parameters. The background information and a table of typical values about each parameter is especially useful.
• Van der Leeden, F. The Water Encyclopedia 1990. Chelsea, Michigan: Lewis Publishers, Inc. A compendium of water-related information in tabular formats. Chapters 6 and 7 pertain to water quality and environmental issues.
• Terrene Institute. Nonpoint Source: News-Notes. This is a bimonthly newsletter published under a cooperative agreement with the U.S. EPA. Water-related environmental issues are highlighted. It is available for free or may be accessed via the Ecolink site below.

Ecolinks On The Web

• http://www.epa.gov/epahome/index.html - US Environmental Protection Agency (US EPA) home page.

• http://www.epa.gov/OWOW/monitoring/ - US EPA water quality monitoring programs and procedures are described here.

• http://www.epa.gov/OWOW/STORET/ - US EPA's STORET database for water quality data. You may obtain water quality data for streams and waterways throughout the United States through the Retrieval Request menu. Follow the on-line directions and be very specific in your request.

• http://www.epa.gov/OWOW/NPS/npsie.html - Nonpoint Source News-Notes. This is an online version of the Nonpoint Source News-Notes, a publication sponsored by the US EPA.

• http://ourworld.compuserve.com/homepages/ottaway/home.htm - Drinking Water Help home page contains questions and answers pertaining to drinking water contamination.

• http://www.mwd.dst.ca.us/pa/docs/terms/glossary.htm - This is a glossary of water-related terms

• http://www.nando.net/nao/neuse/neuse.html - Sold Down the River. The Neuse River in North Carolina has recently gained the dubious recognition of being one of the ten most polluted rivers in the nation. This is a series on the pollution of the Neuse River form the Raleigh NC News and Observer

• http://www.api.org/resources/valdez/ - EXXON Oil Spill Research. Abstracts from research papers on the ecological status of Prince William Sound since the Exxon Valdez oil spill.

• http://www.humnat.org/aws.htm - Flush with Pride! The story of the Arcata, California "constructed wetlands" that are used to treat the City's sewage as well as providing wildlife habitat and salmon aquaculture facilities.

• http://www.cdc.gov/ncidod/diseases/crypto/cryptos.htm - Cryptosporidium Centers for Disease Control and Prevention (CDC) fact sheet about Cryptosporidium

• http://www.ewg.org/pub/home/reports/dishonorable/ddrivers.html - List of the 50 most polluted rivers in the United States.

• Note: If any of these links are not working, please see if alternative links are available at the Ecolink Update Website.

Ecotest Online

1. What are EPA water quality standards?

a. a listing of all pollutants detected in water samples

b. federally certified water quality monitoring stations

c. a description of optimal water quality conditions for specific watersheds

d. threshold concentrations for water pollutants

2. All of the following are examples of nonpoint sources of pollution except:

a. agricultural runoff into drainage ditches

b. aerosol deposition downwind from industrial centers

c. discharge from a sewage treatment facility

d. stormwater runoff from urban streets

3. If nutrients are artificially supplied to aquatic and estuarine ecosystems, excessive plant growth may result and water quality will decline. This form of pollution is called _____.

a. enrichment

b. eutrophication

c. nutrient limitation

d. enhancement

4. Which of these statements about biological oxygen demand (BOD) and dissolved oxygen (DO) in streams is false?

a. BOD is highest and DO is lowest immediately upstream from sewage discharges

b. as BOD increases, DO decrease

c. waters with abundant dead organic matter tend to have high BOD

d. in the polluted zone and recovery zone of a stream, aquatic species that are adapted to low DO are more apt to survive

5. Nitrogen and phosphorus concentrations in streams tend to be highest in streams located in watershed dominated by which land use category?

a. forest

b. urban

c. agricultural

d. industrial

6. An estimated ____ % of the 175,000 known waste disposal sites in the United States may be producing hazardous chemical plumes that could migrate into groundwater.

a. 85

b. 75

c. 55

d. 33

7. Waters are considered too polluted for swimming if fecal coliform concentrations are in excess of ____ colonies per 100 milliliters

a. 50

b. 75

c. 100

d. 200

8. Which statement about the operation of wastewater treatment facilities is false?

a. chlorine is injected into sludge to eliminate bacterial growth

b. secondary wastewater treatment does not eliminate nitrogen, phosphorus, and many toxic materials

c. an aerobic environment is maintained in the aeration tank, whereas, an anaerobic environment is maintained in the sludge digester

d. grit chambers and sedimentation tanks remove approximately 30% to 40% of the pollutant volume from wastewater in the primary treatment phase

9. Which statement about federal water legislation is false?

a. the Water Quality Act (1987) targets point sources of pollution

b. the Federal Water Pollution Control Act was enacted in 1972 during the Nixon Administration

c. the Comprehensive Environmental Response, Compensation, and Liability Act provides funds for clean up at hazardous waste disposal sites, thus reducing groundwater pollution

d. contaminant standards were established in the Federal Safe Drinking Water Act

10. In coastal areas that rely on groundwater supplies, intensive groundwater removal (well pumping) may draw salt water into the freshwater aquifer and contaminate groundwater supplies. This is called ______.

a. salinization

b. salt leaching

c. salt water intrusion

d. deep well injection

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