Chapter 11 Water and Environment

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Chapter 11Water and Environment
Big Question Can We Maintain our Water Resources
for Future Generations?
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Case StudyThe Colorado River

• A study of Water Resources Management, Water
  Pollution, and Environment

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• Two reservoirs (Hoover and Glen Canyon Dam) hold
  80 of Colorado River basin water

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• 1996 experiment water was released for a week
• Flood created 55 new sandbars and made 75 of
  existing sandbars bigger
• Rejuvenated marshes and backwater habitats

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Water

• No water means no life
• High capacity to absorb and store heat
• The universal solvent
• Solid water is lighter than liquid water
• Sunlight penetrates water to variable depths

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A Brief Global Perspective

• Growing global water shortage linked to our food
  supply
• Main process in cycle global transfer of water

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• Most of Earths water is unusable for us
• Compared with other resources, water is used in
  very large quantities
• Can we avoid water shortages?

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Water Sources

• Two main sources groundwater and surface water
• Groundwater
• Upper surface of the groundwater is the water
  table
• An aquifer is an underground layer of rock, sand,
  or gravel containing usable significant amounts
  of groundwater

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Groundwater and surface water flow system
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• Surface water streams, rivers, and lakes
• Streams are classified as
• Effluent or influent
• Perennial or ephemeral
• Streams may have both perennial and ephemeral
  reaches

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• Surface water and groundwater are parts of same
  resource

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Desalination

• Turning sea water into freshwater
• Getting less expensive, but still more than
  traditional water supplies in U.S.
• Desalinated water has a place value the price
  rises depending on how far water must move from
  plant
• Environmental impact of discharge

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Water Supply

• Water isnt always where it is needed.
• Depends on hydrologic cycle
• - rates of precipitation, evaporation, and
  transpiration
• How useful is precipitation water?
• How much water do people use?
• Groundwater is popular for drinking, but can be
  expensive

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• Problem of overdraft - taking more groundwater
  than is naturally replaced

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Off-Stream and In-Stream Water Use

• Off-stream use removing water from source to use
  elsewhere
• In-stream use using water right where it is

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• Example Aral Sea in Kazakhstan and Uzbekistan
• The Aral Sea is drying up and dying due to
  diversion of water for agriculture
• Wake-up call about environmental damage

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Transport of Water

• Moving water to where it is needed is not a new
  idea
• New York City has imported water for over 100
  years
• Today a lot of water comes from upstate forests
• Catskills water was filtered effectively by
  natural processes

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• This natural service became overwhelmed by local
  development and pollution
• New York City decided on sewage treatment rather
  than water treatment in Catskills
• Good water quality maintained by offering
  financial incentives to areas farmers and
  homeowners
• Transporting water has its limits

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Some Trends in Water Use

• Managing and conserving water has improved
• Major water use is irrigation and thermoelectric
  industry
• Irrigation water use began to level off around
  1980
• Thermoelectric and other industries peaked in
  1980
• Use of public and rural water supplies continued
  to increase during 19501995

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Water ConservationAgricultural Use

• Controlling agricultural use is key
• Price water to encourage conservation
• Use lined or covered canals to reduce seepage
• Computer monitoring and scheduled release
• Irrigate when less water is lost to evaporation
• Use improved irrigation systems
• Improve soil for easier water penetration
• Integrate surface water and groundwater use
• Develop crops requiring less water

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Comparison of agricultural practices in 1990 with
what they might be by 2020
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Domestic Use

• Domestic use of water is a small part of the
  total but often a big local problem
• Many urban areas in the United States are already
  experiencing the impact of population growth on
  their water supply
• What are some ways to use less water at home?

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Possible Solutions

• In semiarid regions, replace lawns with
  decorative gravels and native plants
• Use more efficient bathroom fixtures
• Fix all leaks quickly
• Use dishwashers and washing machines that use
  less water
• Sweep sidewalks and driveways instead of hosing
  them

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More possible solutions

• Wash cars at a car wash, where water may be
  reused
• Consider using gray water
• Water lawns and plants in the early morning, late
  afternoon, or at night
• Use drip irrigation and mulch garden plants
• Plant drought-resistant vegetation

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• Industry and Manufacturing Use
• Room for improvement
• curb water withdrawals by water treatment and
  recycling
• Perception and Water Use
• How people view their water supply affects how
  much they use

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Sustainability and Water Management

• Water is essential to sustain life and maintain
  ecological systems
• Sustainable Water Use
• Develop sufficient water resources for human
  health
• Provide sufficient water resources for healthy
  ecosystems
• Ensure minimum standards of water quality
• Protect long-term water resource renewability
• Promote water-efficient technology and practice
• Gradually eliminate water-pricing policies
  encouraging wasteful use

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Water Management and the Environment

• Moving water from one area to another isnt easy
• This creates a good deal of controversy

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Wetlands

• Common feature wet for part of year and have
  particular type of vegetation and soil
• Include salt marshes, swamps, bogs, prairie
  potholes, and vernal pools

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• We need wetlands
• Natural sponge
• Groundwater recharge (water seeps into ground)
• Nursery grounds for fish, shellfish, aquatic
  birds, and other animals
• Natural filters that help purify water
• Highly productive
• Coastal buffer from storms and high waves
• Storage sites for organic carbon
• Aesthetically pleasing

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• Freshwater wetlands are threatened
• Over 50 of the wetlands in the US have
  disappeared
• Salt marshes have also suffered
• The San Francisco Bay estuary
• Redirecting the Mississippi is leading to loss of
  coastal wetlands

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Preserving and Restoring Wetlands

• Offer incentives to wetlands owners
• Related management issue is restoration of
  wetlands
• Construct wetlands to clean up agricultural
  runoff
• Creation of wetlands in Florida to help restore
  Everglades

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Dams and the Environment

• Dam effects include
• Loss of land, cultural resources, and biological
  resources
• Storage of sediment behind the dam
• Fragmentation of river ecosystems
• Downstream changes in hydrology and in sediment
  transport

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• Some dams are being removed
• Example Edwards Dam near Augusta, Maine

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• In contrast, China has recently constructed
  worlds largest dam on the Yangtze River

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• Dams may produce false sense of security
• One positive is dams production of electricity
• More and bigger dams likely if current use
  continues

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Channelization and theEnvironment

• Channelization straightening, deepening,
  widening, clearing, or lining existing stream
  channels
• Can harm environment
• Loss of important fish habitats
• Removal of vegetation along stream banks
• Downstream flooding where channelized flow ends
• Loss of wetlands from drained source water
• Aesthetic degradation

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Case StudyKissimmee River, Florida

• Turning a winding river into a straight ditch and
  back again
• Restoration of Kissimmee River has been no small
  task
• Not all channelization causes serious
  environmental degradation

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Flooding

• Natural hazard in a floodplain
• Flooding has many benefits for the environment
• Water and nutrients stored on floodplains
• Deposits contribute to formation of nutrient-rich
  soils
• Floodplain wetlands provide important habitat
• Floodplain functions as a natural greenbelt

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• Natural flooding is only a problem if people live
  on floodplains
• Example Flooding as a result of levee failure on
  Mississippi River in 1993

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Urbanization and Flooding

• What happens when you build towns and cities in
  drainage basins?
• Faster runoff increases risk of flooding
• Flooding from urbanization can be reduced in
  several ways
• Store runoff in retention ponds or parking lots
• Limit urbanization of floodplains
• Relying on dams, levees, and floodwalls is a
  mistake

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Global Water ShortageLinked to Food Supply

• Isolated water shortages are indicators of a
  larger global pattern
• Surface and groundwater are being stressed and
  depleted
• Groundwater being used faster than it is renewed
• Large water bodies drying up, i.e. Aral Sea
• Large rivers running dry before reaching the ocean

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• Water demand has tripled during the past
  half-century
• Will the supply be sufficient to grow crops for
  the future population?
• For sustainable water resources, we must control
  human population growth

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Water Pollution

• Water pollution lowers quality of water
• Lack of clean drinking water is widespread
• problem killing several million people a year
• The quality of water determines its potential
  uses.
• Many processes and materials may pollute surface
  or groundwater
• EPA sets limits for water pollutants
• More people means more pollutants and greater use
  of water resources

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Sources of Pollution

• Biochemical Oxygen Demand (BOD) amount of oxygen
  consumed by microorganisms breaking down organic
  matter
• Streams and rivers carry organic waste

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• Waterborne Disease public-health programs have
  largely eliminated water-borne disease in the
  United States by treating water
• Fecal Coliform Bacteria an indicator of
• disease potential
• One type, Escherichia coli (E. coli), has caused
  illness and death

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• Threat of disease causes thousands of warnings
  and beach closings each year

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Nutrients

• Land use causes two nutrients to pollute water
• Phosphorus and nitrogen
• May be associated with fertilizers, detergents,
  and products of sewage-treatment plants.
• Large industrial chicken and hog farms are big
  contributors

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• Example North Carolina, 1999
• Floodwaters from Hurricane Floyd carried
  thousands of dead pigs, with their waste matter,
  through schools, homes, businesses

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• People, not a hurricane, caused this
  environmental disaster
• What is the lesson?
• Has it been learned in North Carolina?

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Eutrophication

• Cultural Eutrophication a body of water develops
  a high concentration of nutrients
• Nutrients increase growth of aquatic plants,
  bacteria, and algae

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• As bacteria and algae die, they are decomposed by
  aerobic bacteria
• Reduction of oxygen causes death of other
  organisms

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• Fish do not die from phosphorus poisoning
• Cultural eutrophication is not limited to lakes
• Example The dead zone in the Gulf of Mexico
• Oxygen content is low because of cultural
  eutrophication associated with agriculture in the
  Mississippi River drainage basin
• The level of nitrogen in the river water has
  leveled off

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• Possible fixes
• Reduce fertilizer use
• Restore and create river wetlands
• Use nitrogen-reduction processes at wastewater
  treatment plants
• No easy solution to cultural eutrophication in
  the dead zone

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• Oil Oil spills make headlines, routine discharge
  of oil does not
• Long-term effects of large oil spills are
  uncertain
• Sediment By volume and mass, sediment is our
  greatest water pollutant
• Many human activities affect runoff, erosion, and
  sedimentation

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• Acid Mine Drainage Water from mines has high
  concentrations of sulfuric acid
• Produced when water contacts rock or tailings
  that contain iron sulfide
• A significant water-pollution problem in many
  states

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Surface-Water Pollution

• Pollutants are categorized as coming from point
  or non-point sources
• point sources are distinct and confined, such as
  pipes
• non-point sources are less distinct, and include
  runoff from streets or fields

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• Dealing with surface-water pollution
• Reduce the sources
• Treat the water to remove pollutants
• Convert the pollutants to forms that can be
  disposed of safely

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• Cities are undoing damage theyve done to rivers
• Example Cuyahoga River, Ohio

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Groundwater Pollution

• Groundwater differs from surface water because
• There is a low oxygen concentration
• Breakdown of pollutants does not occur readily
• Water moves slowly through very small and
  variable channels
• Groundwater can be easily polluted by several
  sources

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Principles of Groundwater Pollution An Example

• Old, leaking underground gasoline tanks have
  polluted water and soil
• Cleanup is expensive and involves
• Soil removal and disposal
• Vapor extraction treatment of water
• Bioremediation by microorganisms

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Some Important Points about Groundwater Pollutants

• Some pollutants are lighter than water and thus
  float on groundwater
• Some pollutants are heavier than water and sink
  through groundwater
• Some pollutants have multiple phases liquid,
  vapor, and dissolved
• Cleanup cost and potential harm to life means
  that the emphasis should be on preventing
  pollutants from entering groundwater in the first
  place

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Another Example Long Island, New York

• The most serious groundwater problem on Long
  Island is shallow-aquifer pollution stemming from
  urbanization
• Sources of pollution include urban runoff,
  household, salt used to de-ice highways,
  fertilizers, pesticides, industrial and solid
  waste, and landfills

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Water Treatment

• Most water sources are treated to conform with
  national drinking water standards
• Water is first stored, then filtered and treated
• Drinking water in the United States is among the
  safest in the world
• However, we need to know much more about the
  long-term effects of exposure to low
  concentrations of toxins in our drinking water

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Wastewater Treatment

• Degraded waters must be treated before being
  released back into the environment
• Conventional methods include septic tanks in
  rural areas and treatment plants in cities

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Septic-Tank Disposal Systems

• How does a septic-tank disposal system work?

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• Sewage drain fields may fail for several reasons
• failure to pump out the septic tank when it is
  full of solids
• poor soil drainage, which allows the wastewater
  to rise to the surface in wet weather

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Treatment Plants

• Wastewater treatment has three categories
• Primary treatment removes 3040 of the BOD from
  the wastewater
• Secondary treatment uses bacteria to digest about
  90 of the BOD that entered the plant in the
  sewage
• Advanced treatment is used when additional
  treatment is required
• Nitrogen and phosphorus removal

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Wastewater Treatment Plant
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Boston Harbor Cleaning Up a National Treasure

• More than tea has been dumped into the harbor
  since 1773
• Moving waste disposal farther offshore is a step
  should dilute the pollutants and is a step in the
  right direction
• Any long-term solution must include reducing the
  amount of pollutants at their source
• Deer Island sewage treatment plant

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Land Application of WastewaterAn Old Practice
Made Cleaner

• Land application of untreated human waste was a
  traditional practice
• Today, wastewater is being applied successfully
  to wetlands which are effective in treating
• Municipal and industrial wastewater
• Storm-water runoff
• Agricultural wastewater and runoff
• Mining waters
• Groundwater seeping from landfills

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• Using wetlands to treat wastewater is
  economically attractive.
• The state of Louisiana also uses its wetlands to
  treat wastewater

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• In arid regions, wetlands can be constructed to
  treat poor-quality water
• Example Avondale, Arizona

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Water Reuse

• In Las Vegas, new resort hotels that use a great
  deal of water for fountains, rivers, canals, and
  lakes are required to treat wastewater and reuse
  it

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Water Pollution and Environmental Law

• Federal laws to protect water resources go back
  to the Refuse Act of 1899, enacted to protect
  streams, rivers, and lakes from pollution caused
  by navigation
• The mid-1990s was a time of controversy about
  U.S. water pollution
• Congress attempted to give industry more
  flexibility in choosing how to comply with water
  pollution regulations

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• Apparently, Congress misread the publics values
  on this issue
• There is strong support for a clean environment
  in the United States, and people are willing to
  pay to have clean air and clean water