Water Pollution
Any physical, chemical, or biological change in
water quality that has a harmful effect on living
organisms or that makes water unusable for
desired uses.
Classes of water pollutants
1. Disease-causing agents
2. Oxygen demanding wastes
3. Water-soluble inorganic chemicals
4. Inorganic plant nutrients
5. Organic chemicals
6. Sediments/suspended matter
7. Water-soluble radioactive isotopes
8. Thermal pollution
Pathogens
• Coliform bacteria (fecal coliforms)
• Standard drinking = 0 in 100mL
• Standard swimming = 200 in 100mL
Oxygen demanding wastes
• Organic wastes that can be decomposed by
aerobic bacteria
• Measurement of oxygen required by bacteria is
called BOD = biological oxygen demand
Water-soluble inorganic chemicals
• Acids, salts, toxic metals (mercury & lead)
Inorganic plant nutrients
(fertilizers)
Water-soluble nitrates and
phosphates
– Result indirectly in
depleted oxygen
– Consumption can
lower oxygen carrying
capacity of the blood
Organic chemicals (carbon chemistry)
Oil, gasoline, plastics, pesticides, cleaning
agents, detergents, solvents and others
Silt, sediment, suspended matter
• Insoluble particles of soil and other
• Cause cloudiness in water
– Reduces photosynthesis
– buries fish eggs
– clogs gills
• Silting also fills channels, harbors, and reservoirs
• Measurement is called turbidity
Radioactive Isotopes
Oyster Creek Nuclear Plant
Thermal pollution
• Cool water is drawn in by industrial plants, used to cool
machinery, and returned to river at warmer temperature
• This warmer water lowers D.O.
• Fish can suffer thermal shock
Detecting water pollution
1. Water quality tests
2. Indicator species
Classifying sources of water pollution
Two types:
point and non-point
Point source =
pipes, sewers, ditches
Non-point = runoff from
watershed
EPA estimates that 33%
of all contamination in lake
and estuaries is caused by
runoff
Pollution in streams
Moving waters allow streams to recover more
quickly than lakes
Biodegradable wastes are broken down more
quickly in streams and rivers than in lakes
Lake Pollution
Less mixing in lakes
This makes lakes more
vulnerable to pollution
Fish can’t escape
pollutants
Cultural Eutrophication
Fertilizers,
animal wastes,
Run into lake
Algal
bloom
Algae & duckweed
grow in population
explosion
Aerobic bacteria that break down algae use up oxygen
Which leads to …………
……. a “fish kill”
Prevention
• Advanced waster water treatment
• Bans or limits on phosphates in detergents
• Soil conservation and land-use to reduce runoff
Cleanup
• Dredging
• Removal of excess weeds
Noteworthy cases
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The Great Lakes-pollution(point/non-point)
The Hudson River-PCBs
Chesapeake Bay-pollution(point/non-p)
Colorado River-water rights
Hetch Hetchy Valley-to dam or undam
James Bay, Canada-water diversion
Mono Lake-water diversion, overuse
Aswan Dam
Ocean Pollution
• “The ocean is the ultimate sink”
We live on
coasts
Most affected
• Coastal areas
• Estuaries, wetlands, reefs, swamps
• ½ of world population lives within 150
miles of coast
• Bangladesh, Malaysia, Philippines,
Thailand, Indonesia
• Mediterranean Sea 85% untreated
U.S.
• 35% of raw sewage goes untreated
• Santa Monica
• Chesapeake Bay
– Drains six states
– Only 1% of runoff
goes out to ocean
Ocean Pollutants
• Dredge spoils
– From harbor dredging
• Sewage sludge
– From wastewater and sewage treatment plants
– US banned in 1992
– London Dumping Convention of 1972, 1983, 1994
• Oil (equal to more than 1,000 Exxon Valdez)
Protecting the Coasts
• Prevention
– Separate pipes
– Discourage dumping
– Protect sensitive and
ecologically valuable
areas
– Use eco land-use
planning
– Double hulls on ships
– Recycle oil
• Cleanup
– Improve cleanup
technologies
– Require secondary
treatment of coastal
sewage
Clean Water Act (CWA)
• 1972 Clean Water Act!
• Main goal was to make all surface water
safe for swimming and fishing by 1983
Clean Water Act
• Was first called Water Pollution Control Act,
1972
• 1977 was amended to the Clean Water Act
• 1987 Water Quality Act
• Main goal was to make all surface water
safe for swimming and fishing by 1983
More CWA
• Also sought to restore chemical integrity of
the water
• Some gains have been made over point
source pollution
• Little gains made in non point source
• 1995 established discharges trading policy
And still more laws…
• Source Water Assessment Program (SWAP),
1996
• SWPP, 1996
• Surface Water Treatment Rule, 1996
Clean Water Act Results
• Some gains have been made over point
source pollution
• few gains made in non point source
Results of CWA!
1972
36%
1992
62%
% of US lakes
And rivers
That are fishable and swimmable
Results of CWA
phosphorus
DDT
Laws, Treaties, Legislation
• Safe Drinking Water Act, 1974
• Water Quality Act, 1965
• Clean Water Act, 1972
More Laws
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Emergency Wetlands Resources Act, 1986
Soil and Water Conservation Act, 1977
Wild and Scenic Rivers Act, 1968
Marine Plastic Pollution Research and Control Act,
1987
Ocean Dumping Ban Act, 1988
Oil Spill Prevention and Liability Act, 1990
Water Resources Development Act, 1974
National Estuary Program (NEP), 1987