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42 Cards in this Set
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Conservation
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does not imply NO use by humans but MANAGED or REGULATED USE in order to not deplete resources completely
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Preservation
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objective is to ensure continuity, regardless of their potential utility (when there is not much left – very depleted)
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Consumptive use
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• People harvest natural resources for food, shelter, tools, fuel, clothing
• Well being diminished if denied access to resources in rural areas • Mostly found in developing countries and broad sense in developed world |
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Productive use
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• Exploitation of ecosystem resources for economic gain (goods are harvested and sold to international markets)
• Mostly developed world • Sources of revenue/employment • Collection of wild species for cultivation/domestication |
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Environmental management
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• Seeks to improve environmental stewardship by integrating ecology policy making, planning and social development, and whatever else is needed
• Sustain and improve existing resources • Find and nurture institutions that effectively support environmental research • Monitor and manage • Prevent and resolve environmental problems • Establish limits of resource use and identify new technology and/or policies • Started in the ‘70s to deal with environmental and social issues of environmental dependency |
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Maximum Sustainable Yield (MSY)
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• Highest possible rate of use the system can match with its own rate of replacement or maintenance
• Just the point at which use begins to destroy the system’s regenerative capacity • Applies to harvesting biota, air/water quality, soils, used in timber cutting, fishing, park visitation, pollution • Maximum we can use without hurting/harming it |
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Tragedy of the commons
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• Ruin of the resource
• Problems arise with open access to a common-pool resource but with no/ineffective regulating authority where profit becomes the only motive in exploiting a resource • Can be avoided only by limiting access (which affects the poor) |
• Overfishing – by the ‘60s regions of the sea were seriously depleted by factory ships and modern fish-finding technology
• Mid-70s Law of the Sea expanded a nation’s jurisdiction to 200 miles offshore making most fisheries under the authority of particular nations • World fish catch may appear stable but many species/areas are overfished • Restoring fisheries requires limiting/reducing fishing • Overharvesting – forests are obstacles to conversion to pastures and agriculture land so deforestation is common in developing nations • Forest not really viewed as resources or beneficial • Clear-cutting creates fragmented landscapes |
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Ecosystem restoration of the Everglades
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• Restore native habitats and species
• Increase flow of water (closer to natural path) • Controversy – large amount of water with pesticides from sugar cane crops flow into reefs (major source of pollution) • Stakes holders are the farmers (sugar cane) and NGO (reefs) • Need to rid water of chemicals – remove levees • Restore, protect and preserve species • Promote compatibility between nature and humans |
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Marine Protected Areas (MPAs)
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• Coasts and open oceans closed to all commercial fishing and mineral mining
• Most allow small-scale fishing, tourism, recreational boating • Not all are rigorously managed • Benefits: ecosystem protection, tourism, fish and larvae spill over into surrounding fisheries • Creation of reserves is the most direct path to restoration |
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Ecosystem capital
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natural ecosystems have great economic value, as they provide goods and services that are vital to human well-being
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Demography
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collecting, compiling, and presenting information about human populations
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K- and r-strategists (Humans?)
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• Humans show characteristics from both
• Exponential growth (r-strategists) • High parental care (K-strategists) |
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Paleolithic revolution
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• 50,000 to 10,000 years ago
• Humans lived in small tribes as hunter-gatherers (nomads) • Lived in the natural environmental (high mortality) |
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Neolithic revolution
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• 12,000 years ago
• Humankind produced abundant and reliable food sources through the development of agriculture • Stayed in the same areas • Organization of cities, job specialization and technological innovation • Food preservation and storage development reduced mortality rate |
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Industrial revolution
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Modern science and technology born in 17th/18th centuries (population dramatically rises)
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Technology energized by fossil fuels allowing people to do more ‘work’ than by human or animal power (pollution and resource exploitation)
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Medical revolution
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• Before the early 1800s human populations grew slowly and fluctuated due to epidemic diseases
• High reproductive rates were balanced with significantly higher death rates than is seen today (low population growth rate) • Increased technologies (from the Industrial Revolution) led to high birth rates and low mortality rates (exponential population growth) |
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Agricultural revolution
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Concerns over producing food for the larger population led to increased agricultural efficiency during the Industrial Revolution
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Pesticides, irrigation and fertilizers allowed countries to feed their people (especially with high-yield crops, corn, wheat, rice, etc.)
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Human carrying capacity
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• Humans are subject to limits and natural laws of population growth
• Humans have increased their carrying capacity through technology, agriculture, trade, fossil fuels and medicine • Factors that limit humans are water, energy, forest products, non-renewable resources, land for population etc. • Number of people that the Earth can support depends on living standards • Estimation to be 10 billion – assuming that fertility rates will continue to decline • Disparities between nations |
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Population growth
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• Varied growth by country
• 98% occurs in developing countries • Highest in least developed countries • Two theories to decrease babies (control population growth and poverty) • Faster economic development will automatically slow population growth • Concentration on population policies and family-planning technologies will bring birthrates down (developing countries’ responsibility) |
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Fertility rates (developed vs. developing nations)
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• Developing countries have high birth rates and high death rates
• Developed nations have low birth rates and low death rates • More ‘wealth’ equals lower fertility rates |
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Population profiles
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Colored bar graphs of proportions of certain ranges by gender for a certain year
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Demographic transition (fertility transition, poverty, birth and death rate)
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• Shift in birth and death rates from the ‘primitive’ to the ‘modern’ condition in industrialized countries (high to low)
• Crude birth rate: # of births per thousand people/year • Crude death rate: # of deaths per thousand/people year • Epidemiologic transition: pattern of change in mortality factors • Fertility transition: CBR have declined in developing countries • High birth rate is offset by high CDR (primitive) to CDR and CBR are both low (modern) |
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Poverty cycle/trap
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Poverty, environmental degradation and high fertility drive each other in a vicious cycle
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Overusing resources for survival leads to environmental degradation, which results in more hands being needed and lack of contraceptives for a high fertility and then dwindling resources divided among more people perpetuates poverty
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Millennium Development Goals
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• United Nations developed it in 2000 to help developing nations
• Each goal has measurable indicators to monitor progress (clear set of targets) • These goals will eradicate poverty and hunger • Achieve primary education and gender equality • Reduce child mortality and disease • Improve maternal health • Ensure environmental sustainability • Forge global partnership for development • Achievable with progress in social modernization |
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The World Bank and IMF vs. micro-lending agencies (developing country debt crisis)
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• World Bank and IMF owned by countries that provide its funds
• Help from UN and World Bank have governments of developing nations borrow money • World Bank provides loans and advisory services • Developing countries must manage their own development • World Bank is the major single agency providing aid to developing countries • International Monetary Fund (MF) is an intergovernmental organization that oversees the global financial system • Sometimes efforts exacerbate cycle of poverty and environmental decline • World Bank helped initiate MDGs and believes in environmental improvement as fundamental to reducing poverty • World Bank’s projects have made the cycle of poverty and environmental decline worse • Development projects should generate enough money to repay loans with interest but developing countries have become more indebted • Countries must focus on agriculture to produce cash crops for export (decreasing the ability to feed their own people) • Adopt austerity measures by reducing services • Rapidly exploiting natural resources by making use of ecosystem capital for short-term cash gain |
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Social modernization
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• Reducing fertility rates DOES NOT require the economic trappings of a developing nation
• Improved education (basic literacy and increased child education) • Improving health (lowering infant mortality and improving life expectancy through basic nutrition and hygiene) • Making family planning available and affordable • Enhancing income through job opportunities • Improving resource management and reducing environmental degradation (moving towards sustainability) |
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Coal (uses, drawbacks)
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• Most abundant fossil fuel
• Smoke and fumes pollute cities • Hazardous to mine and dirty to handle • Steam engines are bulky and hard to operate • Burning produces ash • Today, most of U.S. coal use generates electricity (91%) • Also used in steam engines and for cooking, heating and industrial processes • Ranks second globally – 26% and provides US with 23% of energy • The Clean Coal Power Initiative (CCPI) seeks to remove pollutants before and after burning along with obtaining higher efficiencies • Capturing carbon to reduce emissions is very expensive • Produces more greenhouse gases and other pollutants than any other form of energy |
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Oil (uses, reserves, oil field content, recovery)
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• Now the major energy source for the world but coal still predominates in eastern Europe and China
• Transportation – 29% of U.S. energy use (depends on petroleum) and home heating • Estimated reserves can only be found by exploratory drilling • Further drilling determines the extent and depth – more accurate estimates (proved reserves) • The oil content of each field is given in probabilities • P05 = a 5% probability the field contains a given number of barrels of oil (BB – billion barrels) • Oil producers prefer to use P05 or P10 instead of a P90 (gives impression of high amounts of oil in reserves) • Proved reserves depend on economics of extraction • Reserves may be higher or lower depending on the price of oil • Higher oil prices justify exploiting more expensive reserves • Must drill to establish extent and depth • Production: withdrawal of oil • Production from a field does not proceed at a steady rate • Oil is liquid trapped in pore spaces of sedimentary rock • Primary drilling recovery: at first, pressurized oil may gush from a well but only 25% of oil can be removed using conventional pumping (primary recovery) • Secondary recovery: can remove up to 50% of oil by injecting steam, brine and/or, carbon dioxide into the wells (enhanced recovery) • Economics determines the extent of reserve exploitation • More limited than nuclear power |
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Hubbert’s oil curve and peak
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• Conserve – think we have reached peak in 70s
• Geologist Hubbert predicted US production peak between 1965-70 (half of available oil withdrawn and production would gradually decrease as reserves were exploited) • Increasing reliance on foreign cheaper oil leads to Oil Crisis in ’70s (Organization of Petroleum Exporting Countries – OPEC – formed a cartel and halted production for higher prices) – most of balance-of-payment debt where more is bought than we export |
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Natural Gas
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• Large reserves but relatively inaccessible (needs a pipeline or high pressure)
• Can be modified for use in transportation – clean-burning and does not produce hydrocarbons or sulfur oxides • Found in association with oil or drilling for oil • Consists mainly of methane gas, which produces carbon dioxide and water when burned • Burns more cleanly than coal or oil • Instead of venting natural gas into the atmosphere (flaring), pipelines can now transport it • Clean, convenient and fairly inexpensive • Used in industry, residential, and electrical power generation • Supplies 24% of US energy needs and 20.5% worldwide • More limited than nuclear power |
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Electrical power (production, generation, matching sources to uses)
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• Electrical power – amount of work done by an electric current over a given time
• Electricity – energy carrier that transfers energy from a primary source to its point of use – constitutes 33% of energy in US • ELECTRIC GENERATOR: a coil of wire rotates in a magnetic field or a stationary wire within a rotating magnetic field (invented in 1831 by Michael Faraday) • Generators convert mechanical energy into electrical energy (three units of primary energy make one unit of electricity) • Generating electricity requires a primary energy source like: (1) Coal, oil, nuclear, refuse, solar, geothermal energy, gas, water and wind… (2) Which boils water to produce high-pressure steam (3) Which drives a turbine (a kind of sophisticated paddle wheel) (4) Which is attached to a generator • Turbogenerator = turbine and generator combined! • Inefficient – most is lost through heat, resistance and transmission • Energy from fossil fuels transfers pollution • ONLY RENEWABLE SOURCES ARE NON-POLLUTING! • Electricity is expensive and is generated from fossil fuels and nuclear energy • Burning coal results in acid deposition and global climate change • Energy is lost through resistance and heat and the transmission of energy through the wires • Producing electricity from fossil fuels is only 30-35% efficient (conversion losses) • Energy is lost through conversion in several ways: • Heat energy goes up and out of the chimney • Heat energy remains in the spent stream (fossil fuels already used) – not useful • Transmission of electricity through wires • Some energy sources do well in some uses but not in others • Transportation (cars, trucks, tractors, planes, trains) • Nuclear and coal will not reduce the demand for oil because they are not efficient |
Energy use is divided into:
(1) transportation (2) industrial processes (3) commercial (4) residential use (heating, cooling, lighting, appliances) and (5) electrical power |
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Electrical power demand/supply
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• Transportation: 29% of U.S. energy use (depends on petroleum)
• Nuclear, coal, water power are used to produce electricity but natural gas and oil are more versatile sources • Most utility companies are linked into pools • They balance electricity supply and demand • Regardless of daily or seasonal fluctuations • Pools must accommodate daily and weekly demand • Saving energy is equivalent to increasing energy supplies • Baseload: the constant supply of power provided by large coal-burning and nuclear power plants • As demand increases above the baseload, the utility draws on power plants (intermediate and peak-load power sources) that can be turned on and off (including gas, diesel, and hydroelectric plants) – reserve capacity • Brownout: result from a deficiency in available power (cause a reduction in voltage) – reduced voltage • Blackout: a total loss of power (occurs during peak periods or are planned) • In the U.S. demand is rising faster than supply • Reserve capacity has declined to 15% • Summer heat waves are the greatest cause of sudden increased demand • Utilities are being pushed to the edge of their ability to provide electricity on demand (antiquated systems) |
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Fossil fuels (how they are formed, environmental concerns)
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• Crude oil/petroleum, coal, natural gas were formed 100-500 million years ago (Paleozoic and Mesozoic eras) in swamps and shallow seas
• Dead biomass became sediment over time • Pressure and heat converted vegetation to fossil fuels • Coal is highly compressed organic matter that decomposed very little • Nonrenewable - it takes 1,000 years to obtain how much the world uses in a day! • US – leading producer and consumes most fossil fuels |
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Mountaintop mining/strip mining
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• Mountaintop mining: must bomb the top to get below and is a surface mining practice involving the:
• Removal of mountaintops to expose coal seams making it easier to extract • Disposing the associated mining overburden into adjacent valleys -- "valley fills” – (debris) |
Strip mining: dynamite breaks layers and shovels remove coal – not environmentally sustainable
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Nuclear power (how does it work, uranium, fission, nuclear reactors, advantages, hazards, radiation, examples of nuclear catastrophes, waste disposal, 235U vs. 238U)
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• The objective of nuclear power: to control the nuclear reaction so energy is slowly released as heat
• Heat boils water to produce steam and the steam turns a conventional turbogenerator • Nuclear plants/reactors are baseload plants: always operate (except during refueling) and are large (up to 1,400 MW) • Nuclear energy is different because it involves changes at the atomic level (unlike chemical reactions of fossil fuels) • Fission: a large atom of one element is split into two atoms of different elements (uranium) - separation • Fusion: two small atoms join to form a larger atom of a different element – conjunction (energy emitted by Sun) • Fission and fusion results in less mass than starting materials (huge release of energy from small loss of mass x speed of light squared) E=mc2 (energy=mass x constant speed of light squared) • U.S. uranium deposits are in Wyoming and New Mexico • The ore is mined/dug from underground or open pits and milled: crushed, chemically treated, and turned into yellowcake (80% UO2) • Enrichment: separates 235U from 238U to produce 3%–5% 235U (the rest is 238U) – this enrichment prevents most developing countries from using nuclear energy • All nuclear plants use fission (splitting) of uranium-235 • Uranium occurs naturally in the Earth’s crust and exists in two forms: uranium-238 (238U) and uranium-235 (235U) • Different mass numbers (# of protons and neutrons combined) come from different numbers of neutrons • 235U readily undergoes fission, but 238U does not • Fission occurs when a neutron hits the nucleus of 235U at just the right speed • Some atoms of 235U undergo radioactive decay and release neutrons and these neutrons can hit other 235U atoms, producing highly unstable 236U, which undergo fission into lighter atoms (fission products) • Energy and fission byproducts are produced • More neutrons build up and are added and more neutrons are given off, releasing lots of energy and this domino effect causes a chain reaction • A nuclear reactor has a continuous chain reaction but does not amplify it into an explosion • Control is through enriching uranium to 3–5% 235U • Highly enriched 235U undergoes spontaneous fission and can trigger a chain reaction, producing a nuclear bomb • Faster neutrons absorbed by 238U convert it to 239Pu (plutonium also undergoes fission and releases energy – about 1/3 of the energy in nuclear reactors) • Moderators surround the enriched uranium (slowing down neutrons to the right speed to trigger another fission) • Uranium is placed into fuel rods in order to achieve the correct reactions • 238U go too fast so only 235U are used • Nuclear reactors are made up of fuel elements, moderator-coolant, and movable control rods • Water is boiled to make steam to drive turbogenerators (boiling-water reactor) • Most are pressurized-water reactors where water is heated to a high temp but does not boil due to high atmospheric pressure to produce steam • If the reactor vessel cracks the core can overheat, causing fission to cease but can still overheat because of the radioactive decay causing a meltdown • Nuclear power has few emissions There is enough uranium for many years of nuclear power Can provide a relatively cheap electricity source • Direct products: split “halves” after elements undergo fission are lighter elements and generally unstable (radioisotopes) – high-level wastes • Radioactive emissions: particles and radiation together • Indirect products of fission: materials in and around the reactor can become radioactive by absorbing neutrons – low-level wastes • Radioactive wastes: direct (splitting apart of atoms) and indirect products of fission • Radioactive emissions can penetrate biological tissue resulting in radioactive exposure Breaks chemical bonds or changes molecular structures at the atomic level Is not felt or seen, but impairs molecular functions (from ionization) • High doses of radiation can prevent cell division • Radiation sickness: exposure prevents replacement or repair of blood, skin, other tissues (can lead to death in days, months or even immediately) • Low doses over long periods can damage DNA (through mutations or malignant tumors) • Background radiation is the main source of radiation exposure for most (mostly X-rays and CT scans) • Direct fission products remain within the fuel elements while the indirect products stay within the containment building housing the reactor • Normal operation of a nuclear power plant is less than 1% of natural background radiation • The main concern is not from normal operations, but from storage and disposal of wastes and the potential for accidents (potential for accidents being the greatest) • Radioactive isotopes of 238U can be recovered and reprocessed but concerns over 239Pu for nuclear weapons prevent the US from employing this practice • Some of the worst failures in handling radioactive waste occurred at U.S. and former Soviet Union military facilities (causing cancer) Leaking liquid wastes contaminated water, wildlife, soil sediments, and groundwater Many places have deliberately released materials because of cost • Development of nuclear power went without first solving the issue of waste disposal Assumed geologic burial Short-term containment: allows radioactive decay of short-lived isotopes (by-products) In 10 years, fission wastes lose 97% of radioactivity (pools to remove radioactivity) Spent fuel is stored in deep swimming-pool like tanks (spent fuel rods are too hot) Water dissipates waste heat to prevents escape of radiation Can hold 10–20 years of spent fuel • Long-term containment: the EPA recommends a 10,000-year minimum Geologic burial seen as the safest option for disposing of highly radioactive spent fuel – salt mine – salt seals in radiation by self-sealing contraction - cementation • No nation has buried the fuel (many nations haven’t even found burial sites – hard to find stable areas) Most waste is held above ground next to the reactors (civilian waste – can lead to meltdowns) We can’t guarantee a stable rock formation for tens of thousands of years Possible volcanoes, earthquakes, groundwater leaching |
• Nuclear catastrophes
3-mile Island Pennsylvania – 1979 – near Harrisburg – reactor cooled off but secondary cooling system failed and radiation was released into the air via steam (pressurized water reactor) – pressure built up until a relief valve blew Chernobyl, Ukraine – 1986 – most notable and most widely cited nuclear failure in history – although control rods slowed down the neutrons fission continued causing a complete meltdown and fire that burned for days • Passive (engineering that makes it virtually impossible for reactors to go beyond acceptable levels of power) are advocated over active (operator-controlled actions) safety |
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Coal vs. nuclear power plants (Baseload plants need to be replaced with other baseload plants)
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Coal-fired power plant (1,000 MW)
Uses 3 million tons of coal Strip-mining causes environmental damage, acid leaching into water Deep mining causes deaths and harm to health (deeper than nuclear) Emits 7 million tons of CO2 and 300,000 tons of SO2, particulates and other pollution Releases 100 times more radioactivity than a nuclear plant Produces 600,000 tons of ash that require disposal but can be reused) Worst-case accidents can result in fatalities and destructive fires |
Nuclear power plant (1,000 MW)
Uses 30 tons of uranium Energy from fission of 1 lb of uranium equals 50 tons of coal Does not emit CO2 when operating but fossil fuels energy is used in mining and enriching the uranium Produces no acid-forming pollutants or particulates Low levels of waste gas 250 tons of highly radioactive wastes require storage and disposal Accidents can range from minor to catastrophic Meltdowns cause huge radioactivity |
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Hydroelectric power (benefits, disadvantages, dams, Belo Monte dam in Brazil)
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• Already heavily developed
• Energy from the Sun is the driving force behind dams, firewood, windmills, sails • The force of falling water can turn paddle wheels • Hydropower: hydroelectric dams use water under high pressure to drive turbogenerators • Worldwide, dams generate 19% of electrical power and it is the most common form of renewable energy • Benefits: Eliminate the cost and environmental impacts of fossil fuels and nuclear power (last longer) Provide flood control and irrigation water (turn off and provide food) – though many that impede natural flow are being removed Reservoirs provide recreational and tourist opportunities Pumped-storage power dams can pump water to a higher reservoir for later use during peak times • Disadvantages: Reservoirs drown farmland, wildlife habitats, towns and of historical, archaeological, or cultural value Reservoirs displace rural populations In the last 50 years, 40–80 million have been displaced Impede or prevent migration of fish (cannot get upstream) Wreak havoc downstream by causing decreasing sediment loads (changing habitats in faraway locations) |
• Belo Monte dam in Brazil (Amazon):
Brazil’s President signed it into law already avowing it as true and inevitable for the future economy |
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Wind power (design, benefits, advantages)
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• Form of indirect solar energy
• The U.S. is the world leader in wind energy. • Second largest renewable energy source in the world (behind hydropower) and is economically competitive with conventional energy sources through subsidies • Now supplies 1.5% of global electricity demand • The most practical design is using wind-driven propellers • The propeller shaft is geared directly to a generator • Wind turbine: a wind-driven generator • Wind farms: arrays up to several thousand turbines • Benefits: Produces pollution-free power competitive with traditional sources and with huge amounts to be tapped into No limitations on growth Offshore wind farms use dependable, strong winds (oceans) They have less of a visual impact Land does not need to be bought • Disadvantages: Wind is intermittent, so backup or batteries are needed Wind farms can be visually unappealing (NIMBY) Turbines can be hazardous to birds When placed on migratory routes or in critical habitats But far fewer die than from cars, traffic, and windows |
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Solar power (uses, PV cells, criticisms)
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• Using solar energy does not change the biosphere’s energy balance (not taking energy away) – solar energy absorbed is converted to heat energy
• Solar energy is abundant but diffuse (widely scattered) Varies with season, latitude, and atmospheric conditions (pollution) • Using solar energy requires turning a diffuse, intermittent source into a usable form (fuel, electricity) • Collection, conversion, and storage of solar energy are difficult and must be cost effective • Criticized for needing a backup heating system Good insulation minimizes this need (keeping heat in) Backup can come from a small wood stove or gas heater • This criticism misses the point: The objective of solar heating is to reduce dependency on conventional fuels Fuel demand is reduced, and the economic and environmental costs are also reduced • Solar energy can produce electrical power Providing an alternative to coal and nuclear power • •Photovoltaic (PV) cells: a wafer of material (solar cell) One wire is attached to the top, one to the bottom Sunlight striking the wafer puts out 1 watt of power 40 linked PV cells produce enough energy to light a light bulb Heated liquid flows to a heat exchanger to drive a turbogenerator or a tank to store the heat Silicon, one of the most abundant elements, is the main material used in solar cells No moving parts and do not wear out but may deteriorate due to weather exposure • Disadvantages: More expensive than conventional sources, needs a backup source and is limited to certain areas and only during the day (although savings are still possible) • Benefits: Viable alternative for coal and nuclear-powered electricity with less financial risk No hazardous wastes produced, geographically dispersed and generally very safe |
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Burning waste and biomass
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• Facilities can generate electricity from burning
• Oldest form of energy throughout history • Biomass energy: energy derived from present-day photosynthesis • Leader over hydropower in renewable-energy production in US (heat) • Firewood: wood stoves (mostly consumptive use in developing countries) • Municipal wastes (waste-to-energy) • Wood wastes: sawmills, woodworking companies (extra materials) Cane wastes: sugar refineries (biomass for electricity) Olive oil wastes: provides electricity to 100,000 homes in Spain The power may meet only a small percent of electrical needs at a local level but it is a productive, inexpensive way to dispose of biological wastes • Methane: fermentation of sewage to yield biogas, a great fertilizer |
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Geothermal energy
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• Geothermal energy: using naturally heated water or steam to heat buildings or produce electricity
• Around the world, springs yield hot, almost boiling, water Also have natural steam vents and other thermal features • •These features occur where the hot molten rock of Earth’s interior is close enough to heat groundwater Near volcanic regions (out West/Hawaii) • •US is world leader in use • •Heat-pump systems are effective for heating and cooling but are slightly more expensive |
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Tidal wave and power
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• The twice-daily rise and fall of ocean tides have a phenomenal amount of energy (when waves break)
• Tidal barrage: a dam is built across the mouth of a bay • Incoming and outgoing tides turn the turbines • 30 locations have tides high enough for this use (Northwest/Washington) • Benefits: limitless and pollution-free • Adverse environmental impacts: • Traps sediments, impedes fish migration, prevents navigation, and changes water circulation patterns (similar to dams) |
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