1. Chapter 10 Water: Resources and Pollution
This slide set includes lecture material on Water: Resources and Pollution, for Chapter 10 Environmental Science by Cunningham and Cunningham.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. Chapter Ten Topics Water Resources Major Water Components
Water Availability and Use
Freshwater Shortages
Water Management and Conservation
Water Pollution
Water Quality Today
Pollution Control
Water Legislation
Within Chapter 10 will study the 9 topics listed here. These topics include water resources, major types of water, water availability and its use by Society, water's role in the environment, shortages of fresh water, how we manage and conserve water, the pollution of water, present with water quality, water pollution control, and laws and legislation that act to conserve and protect water resources. There is no question about it, water is a very, very big issue in Environmental Science. In particular, in the arid West water is the issue, period.

3. Mean Annual Precipitation
The distribution of precipitation in different parts of the earth is certainly not even. Lack of precipitation, either regularly or seasonally, is the source of enormous human suffering. The amount of precipitation a particular area receives largely dictates the nature of vegetation and animals there. Such human suffering is prevalent in northern Africa where this map shows that less than 25 cm (10 inches) of rain falls per year.

4. Part 2: Major Water Compartments
Most of the water on the earth is located in the oceans and saline lakes, with just 2.4% of the Earth's water in the form of fresh water. Eighty-seven percent of earth's fresh water is located in ice and snow, primarily in the world's glaciers. Most of this ice occurs in Greenland and Antarctica. Of the 13% of earth's freshwater that is in the form of liquid water most is in the earth's groundwater and most of this ground water is relatively inaccessible to society. About 3% of the total liquid fresh water on the earth is located in lakes, rivers, and streams and roughly 2% is stored as soil moisture. Most of the water that society uses comes from lakes, rivers and streams, though only a small proportion of those are near enough to the areas where water is used to be practical.
In certain areas (for instance, in the area east of Tacoma called the Clover-Chambers Creek region) groundwater is the primary source of fresh water for societal consumption. In some areas, (such as parts of Saudi Arabia where fresh water is very scarce) salt water resources are utilized to produce fresh water for human consumption and even for irrigation of crops. Desalination requires tremendous amounts of energy, and most of that energy is acquired from the abundant oil resources in Saudi Arabia.
There also have been proposals to tow icebergs to regions that need fresh water. Though this has never been carried out, glaciers in the oceans are composed of freshwater and also could be a potential source of water for society.

5. Interactions of water with soil.
Groundwater, after ice, is the 2nd largest reservoir of fresh water
Infiltration - Process of water percolating through the soil and into fractures and permeable rocks.
Zone of Aeration - Upper soil layers that hold both air and water.
Zone of Saturation - Lower soil layers where all spaces are filled with water.
Water Table is at the top of the Zone of Saturation
Precipitation that does not run off or evaporate percolates through the soil in a process called infiltration. This water interacts with the soil, first adsorbing nutrients and then later releasing them to plant roots, microorganisms or soil at deeper depths. Water that infiltrates soil can be a source for ground water. The zone of saturation is often the source of water for wells. The top of the zone of saturation is called the water table.

6. Recharge zones - areas where surface waters
Aquifers
Aquifers are porous underground layers that contain water. Besides water, aquifers typically contain porous layers of sand, gravel and rock lying below the water table. In cases where aquifers are used to supply water, they typically are closer to the surface of the earth and near areas where the water is required.
The components of an aquifer include an aquitard (confining layers that keep water from moving further into the earth) and the water bearing porous zone. In cases where the aquifer is confined above as well as below, the water bearing zone rises above the land surface. Wells drilled into the aquifer will likely flow freely from natural pressure. This is termed an artesian well. Sometimes artesian wells occur naturally.
The recharge zone is where water infiltrates into an aquifer. Recharge rates are often very slow. Currently, humans are removing ground water from aquifers faster than the aquifer can be recharged resulting in a net loss of groundwater.
Recharge zones - areas where surface waters
filter into an aquifer

7. Wetlands - Play a vital role in hydrologic cycle.
Rivers, Lakes and Streams - Precipitation that does not evaporate or infiltrate into the ground runs off the surface, back toward the sea.
Best measure of water volume carried by a river is discharge.
The amount of water that passes a fixed point in a given amount of time (usually expressed as cubic feet per second).
Wetlands - Play a vital role in hydrologic cycle.
Lush plant growth stabilizes soil and retards surface runoff, allowing more aquifer infiltration.
Disturbance (including urban development) reduces natural water-absorbing capacity, resulting in floods and erosion in wet periods, and less water flow the rest of the year.
Other, smaller compartments of water include rivers, lakes, streams, wetlands and the atmosphere. The length of time water typically stays in a compartment is called its residence time. A water molecule has a residence time of approximately 3000 years in the ocean. In a living organism the residence time is about a week. In saline or fresh groundwater, the residence time can be as high as thousands of years depending on depth and other factors. Water in aquifers with long residence times can be made permanently unusable if pollutants are carried in from above since there is little turnover. Water in such aquifers is, for all practical purposes, non-renewable.
The Atmosphere - Among the smallest water reservoirs.
Contains 0.001% of total water supply.
Has the most rapid turnover rate.
Provides a mechanism for distributing fresh water over landmasses and replenishing terrestrial reservoirs.

8. Rivers, Lakes, and Wetlands
Rivers contain a minute amount of water at any one time.
Lakes contain 100 times more water than all rivers.
Wetlands play a vital role in the hydrological cycle.
As mentioned earlier, lakes, rivers and other freshwater surface water contain only a very tiny (only 3% of the total liquid freshwater on earth) amount of the year's total water; however, during a single year the amount of water contained in rivers and streams will be replaced many times (short residence time), making these an extremely important mechanism for the movement of water in the water cycle. In most cases, the water in lakes is also replaced over time, but the hydrological retention time in lakes is quite variable.
In cases where water does not eventually flow to the ocean, dissolved salts can accumulate and form a saline lake. Good examples of this happening are seen with the Dead Sea or Great Salt Lake. These bodies of water can have salt concentrations many times higher than the ocean itself. Wetlands, in which the majority of the water is near the surface of land, play an extremely important role in local water storage, regulation of water flow, purifying water, and as nurseries for many organisms (even a large number migratory organisms whose life cycle is otherwise spent in habitats other than wetlands).
Table 10.3 shows the world's ten largest rivers in terms of their average discharge of water. Notice that the Amazon River of South America dwarfs all other rivers of the world. The flow of the Amazon River nearly equals the flow of the world's next nine largest rivers. Anyone who has ever traveled on the lower part of the Amazon River can testify that it seems more like traveling on a large lake than flowing down a river.

9. Part 3: Water Availability and Use
Clean, fresh water is requisite for human survival.
Renewable water supplies consist of surface runoff and infiltration into accessible freshwater aquifers (shallow ground water). These supplies are most plentiful in the Tropics.
Picture to the left shows a ditch being used to divert water for irrigation of crops. Water rights for such activities have long been a source of tension and conflict.
Water availability and quality has always been a primary concern for human survival. Humans require about a gallon of water per person per day. Clean water is not only an important input directly into humans, but it is also necessary for the production of food, for carrying out industrial processes, and for removing wastes from contact with humans. The city of Seattle, for instance, spends hundreds of millions of dollars per year to provide high-quality water to the region. In addition, many hundreds of millions of dollars per year more or spent to purify water that has been used in order to assure that discharge of wastewater does not degrade the quality of other water bodies (for example, Lake Washington and the Puget Sound).

10. Part 4: Freshwater Shortages
About 25% of the world's people lack adequate, clean drinking water and about 50% lack adequate sanitation.
Water stress is a phrase used to describe countries where water consumption exceeds by >20% the available, renewable water supply
Widespread water shortages are predicted by 2025.
Shortages of fresh water required by humans are just as much a shortage of high-quality water as they are of water itself. One of the important rituals that surrounds life in many of the poorer countries of the world is the daily or more than daily visit to the water supply. In some cases, these trips are to a contaminated water source. It is relatively rare (>2/3's of world's households retrieve water from outside the home) that water is acquired simply by opening a valve for most people in the world.
Today, 45 countries (mostly in Africa and the Middle East) cannot meet the minimum essential water requirements of their citizens. In fact less available water often costs more, and sanitation levels decline when water is expensive. An estimated 1.1 billion people lack access to an adequate supply of drinking water and 2.4 billion lack acceptable sanitation. Globally, water supplies are abundant, but (along with capital resources) water is an unevenly distributed resource.

11. Water used for irrigation accounts for nearly half of all water consumption in high income countries and most water consumption in poor countries. When the utilization of water and agriculture is at odds with other uses (either by cities or to protect environmental considerations such as salmon) water becomes even more valuable as an agricultural commodity.
In the State of Washington, irrigation of crops on the east side of the Cascades is a multi-billion dollar part of the Washington economy, employing several million people directly or indirectly. In my travels, I have bought Washington apples throughout the United States, in every country I've been to in Europe, and in China, Indonesia, Taiwan, Japan, and Brazil. Previously, most technology for irrigation was devoted to simply moving more water to agricultural fields and applying it. In areas where irrigation water is extremely valuable and scarce, techniques such as drip irrigation can be used to conserve water.
Avoiding salt buildup in irrigation is a major concern where there is no wet period in which water percolate to the low soil depths. On the east side of the Washington Cascades, flowing streams are created from the excess water applied to agricultural fields. For areas like the Winchester waterway, these can become important wildlife habitat. In contrast, at other irrigation projects (for example, the Kesterson Wildlife Refuge in California) toxins such as selenium can build up and cause environmental problems.

12. Depleting Groundwater
Groundwater provides nearly 40% of the fresh water for agricultural and domestic use in the United States. In many areas in the U.S., groundwater is being withdrawn from aquifers faster than natural recharge can replace it.
Withdrawing large amounts of groundwater in a small area causes porous formations to collapse, resulting in subsidence.
Sinkholes form when an underground channel or cavern collapses.
Saltwater intrusion can occur along coastlines where overuse of freshwater reservoirs draws the water table low enough to allow saltwater to intrude.
Ogallala Aquifer (large aquifer in the Central Plains) - water usage here is the similar to mining for a nonrenewable resource and the water resource is being depleted rapidly.
San Joaquin Valley, California - ground surface sinking is occurring due to excessive groundwater pumping.
Groundwater provides about 40% of the fresh water supply for agricultural and domestic consumption in the U.S., with about half of all Americans in about 95% of people living in rural areas getting their water supply from groundwater. Problems of the supply of ground water follow a familiar story. The very first people to drill a well typically have no problem with groundwater supply. As more and more people use a particular source of groundwater, and as each person increases their individual consumption by irrigating their lawn, filling their swimming pools, watching cars, and other uses, the consumption can exceed the recharge of groundwater. This can occur on a small or large scale. For instance, the Ogallala aquifer underlies eight relatively dry States from Texas to North Dakota. Use of water from the Ogallala aquifer greatly exceeds the recharge of water into the aquifer over much of its area. As the water table drops, wells that previously produced water dry up, and of course, the response is to drill wells deeper and deeper. When the bearing of load from groundwater is released land can also subside above the aquifer. For instance, in the San Joaquin Valley in California land surfaces have sunk as much as 10 m over last few decades because of excessive groundwater pumping. In many cases, large scale utilization of groundwater is more like mining an irreplaceable mineral that using a renewable resource because of the very slow replacement of groundwater by recharge.

13. Ways to Increase Water Supplies
Building Dams, Canals and Reservoirs
Seeding Clouds
Condensation Nuclei
Towing Icebergs
Cost
Desalination
Most common methods are distillation and reverse osmosis.
Three to four times more expensive than most other sources.
There are ways to increase water supplies, but, at first glance, some may seem impractical. Building dams, canals and reservoirs is probably the most practical approach; yet, as large projects to produce these features have increased, more environmental and political problems with these approaches surface. We will talk about these problems next.
Of course, the easiest and cheapest way to have more water is to use what we have more efficiently and use less.

14. Dams are controversial in terms of environmental costs, justice, price mechanisms and water policy, sedimentation, evaporative losses, etc.
Perhaps, the first major dam controversy in the United States was associated with the damming of the Hetch Hetchy Valley to provide electricity and water to San Francisco. Remember the picture of John Muir and Teddy Roosevelt in the Yosemite Valley from Chapter 1. Missing from that picture was Gifford Pinchot who is considered to be the father of forestry in the U.S. Pinchot and Muir worked closely together to conserve and protect American natural resources until they went different ways regarding the Hetch Hetchy Dam. Pinchot wanted to see water and electricity made available to San Francisco. Muir favored preservation of the valley in its natural state. The growth of San Francisco and the American West largely dominated policy, and the Hetch Hetchy valley was flooded.
Similarly, the water of the Colorado River backed up by the Glen Canyon Dam flooded a spectacular canyon and changed sediment deposition patterns downstream in the Grand Canyon.
Throughout most of U.S. history, water policies have generally worked against conservation. In general, these are summarized geographically as:
Eastern - Riparian Use Rights
Western - Prior Appropriation Rights
In most federal reclamation projects, customers have been charged only for the immediate costs of water delivery. For instance, review the Klamath reclamation project case study on page 233 of the text.

15. Part 5: Water Management and Conservation
Watershed management
Sound farming and forestry practices
Wetlands conservation
Domestic conservation
Water reclamation and recycling
Water rights
The management and conservation of water is typically far more economical and environmentally acceptable than developing new sources of water supply. The practice of watershed (all the land drained by a river) management is becoming a universal way of providing high quality water to cities and other users of water while preserving the watersheds that produce that water. Retaining crop residue on fields reduces flooding and minimizes plowing and lessening forest cutting on steep slopes protects watersheds. Retaining vegetation and ground cover helps retard rainwater and lessens downstream flooding.
In particular, the city of Seattle takes nearly all of its water from two sources, the Cedar River watershed and the Tolt watershed (both are east of Seattle). Access to these watersheds is restricted, and any management practices that take place within the watershed must do so considering that the first priority is production of high-quality water for the city of Seattle and the region. Since farming and forestry are practiced on large areas of land that produce water from runoff, maintaining vegetation and protecting soil from erosion not only protects the soil resource, but also insures the production of high quality water.
In addition, the protection of wetlands aids in the production of high-quality water because of their filtering function. Wetlands sometimes also function as major sources of groundwater recharge. Conserving water wherever it is used means that less water must be provided. This means that marginal sources of water, economically and environmentally, need not be developed. Presently, Seattle has plans to reclaim and recycle waste water produced from its sewage treatment plants, not for human consumption directly, but to use this water for industrial processes and irrigation. Finally, the assignment of rights to the use of water must address water use goals.

16. Domestic Conservation
Estimates suggest many societies could save as much as half of current domestic water usage without great sacrifice or serious change in lifestyle.
Largest domestic use is toilet flushing.
Small volume of waste in large volume of water.
Significant amounts of water can be reclaimed and recycled (purified sewage effluent)
As mentioned at the start of this part on water management and conservation, of the 3 R's (reduce, reuse and recycle), reduce is always the cheapest and easiest.

17. Part 6: Water Pollution
Point source pollution - source is from drain pipes, ditches, sewer outfalls, factories and power plants - easy to monitor and regulate
Nonpoint source pollution - runoff from farm fields and feedlots, lawns and gardens, golf courses, construction sites, atmospheric deposits - no specific location so harder to monitor and regulate
Water pollution is defined as any physical, biological, or chemical change in water quality that adversely affects living organisms. There are many different potential sources of water pollution, but commonly all sources are divided into two distinctive types: 1) point source pollution is where water is collected into a single place before being discharged; and, 2) nonpoint source pollution is where pollution has a scattered or diffuse source (from an area rather than a single point). Urban pavement and rooftop runoff during storms are examples of non-point source pollution.
One of the major advantages associated with controlling point source pollution is that typically a single entity can be identified as its source; thus, efforts at water pollution control have been very successful in cleaning up point sources of pollution. In the 60's, Lake Washington was cleared of point-source pollution (mostly sewage), but today it is suffering from non-point source (urban runoff) pollution. Usually, nonpoint source pollution is a harder problem to fix compared to a nonpoint source problem such as that of Lake Washington in the 60's.

18. Types and Results of Water Pollution
Infectious agents - 25 million deaths a year
Organic materials - biological oxygen demand (BOD) increase resulting in oxygen sag
Plant nutrients - eutrophication, toxic tides
Metals - mercury and lead poisoning
Nonmetallic salts - poison seeps and springs
Acids and bases - ecosystem destabilization
Organic chemicals - birth defects, cancer
Sediments - clogged estuaries, death of coral reefs
Thermal pollution - thermal plume
The actual agents of water pollution are numerous, including biologically infectious materials, organic materials whose effect is primarily through the reduction of dissolved oxygen and water (termed biological oxygen demand or BOD), plant nutrients that can lead to excess biological growth, toxic metals such as lead and mercury, acids and bases, toxic organic compounds, eroded sediment material that can clog waterways, and heat, which can change the nature of biological systems.
As a trout fisherman, for instance, I know that trout prefer cold, highly oxygenated water. When thermal pollution or excess BOD is introduced into a stream, typically other species of fish (such as bass or even carp in extreme cases) replace the trout,.

19. Infectious Agents
Main source of waterborne pathogens is untreated and improperly treated human waste.
Animal wastes from feedlots and fields is also an important source of pathogens.
In developed countries, sewage treatment plants and pollution-control devices have greatly reduced pathogens.
Tests for water quality are done for coliform bacteria (intestinal bacteria). Such tests are easier and cheaper.
Escherichia coli (E. coli) is the major coliform bacterium species
Whenever coliform (intestinal) bacteria are present in high concentrations, other more pathogenic microorganisms are also present. A relatively quick and inexpensive method of testing for these organisms is to use a serial dilution of a known quantity from water collected from the site of interest. After incubating the tubes, the diluted samples can be plated on a petri dish with agar and the number of colonies that result can be used to calculate the original concentration of coliform bacteria. Presumably, each colony was originally derived from a single bacterium cell.

20. Basics for Understanding Environmental Implications of Oxygen-Demanding Wastes
Water with a Dissolved Oxygen Content (DOC) content > 6 parts per million (ppm) will support desirable aquatic life, whereas water with < 2 ppm oxygen will support mainly detritivores and decomposers.
Oxygen is added to water by diffusion from wind and waves, and by photosynthesis from green plants, algae, and cyanobacteria. Oxygen is removed from water by respiration and oxygen-consuming processes.
Biochemical Oxygen Demand (BOD) is the amount of dissolved oxygen consumed by aquatic microorganisms in respiration.
When organic wastes are added to rivers, microorganisms demand oxygen for respiration used in consuming the increase in food resource. As a result, DOC levels decline downstream (oxygen sag) from a pollution source as decomposers metabolize organic waste materials.
The next slide summarizes the detailed text for this slide. Read this slide first and then see if you can explain what the figure on the following slide is depicting. Oxygen sag refers to the shape of the dissolved oxygen curve downstream from the point source of pollution (it sags and then slowly comes back).

21. Oxygen sag
Perhaps the most serious kind of water pollution overall is caused by relatively innocuous substances in the wrong place at the wrong time. Biological Oxygen Demand (BOD) and its tendency to remove dissolved oxygen from water is the most serious type of water pollution worldwide because of the negative impact it has on oxygen requiring organisms that live in water.
Whether or not a substance is a pollutant, in some ways, is similar to asking whether or not a plant is a weed. Pollution is defined as water that has a substance in it in sufficient quantities that makes it unsuitable for a particular purpose. That purpose can be as habitat for trout (where cold highly oxygenated water is desirable) or as water suitable for operation of a steam boiler (where dissolved salts would be the most serious pollutant possible).
For instance, one of the most memorable events of water pollution that I can think of in my life was when a milk truck hit a bridge abutment and flipped over into the middle of Deer Creek where I often fished as a child. As soon as the milk mixed with the stream water, microbes began to use the milk organic substances as a food source through respiration. This increase in respiration removed oxygen from water in the stream. A slug of deoxygenated water move downstream. After the oxygen content of this water dropped below a certain level, all of the fish in Deer Creek died (an estimated 10 million in all). I don't believe Deer Creek has ever recovered from that single event in terms of its quality as a trout stream.

22. Plant Nutrients and Cultural Eutrophication
Oligotrophic - Bodies of water that have clear water and low biological productivity.
Eutrophic - Bodies of water that are rich in organisms and organic material.
Eutrophication - Process of increasing nutrient levels and biological productivity.
Cultural Eutrophication - Increase in biological productivity and ecosystem succession caused by human activities.
An excess of nutrients in water causes accelerated plant growth. Though this is a natural process, it is accelerated when nutrients higher than natural levels enter the water body. Typically, this stimulates the growth of algae and aquatic plants, alters the composition of other species, and makes the water body unsuitable for recreation and other uses. Lake Sammamish, for instance, has had increasing levels of phosphorous enter the lake since the 1960's. Nearly every year now, there are major algal blooms on Lake Sammamish. Such algal blooms are not documented in the history of Lake Sammamish prior to the increase in phosphate levels from urban sources.

23. Inorganic Pollutants Metals
Many metals such as mercury, lead, cadmium, and nickel are highly toxic.
Highly persistent and tend to bioaccumulate in food chains.
Lead pipes are a serious source of drinking water pollution.
Mine drainage and leaching are serious sources of environmental contamination.
Nonmetallic Salts
Many salts that are non-toxic at low concentrations can be mobilized by irrigation and concentrated by evaporation, reaching levels toxic to plants and animals.
Leaching of road salts has had detrimental effect on many ecosystems.
Acids and Bases
Often released as by-products of industrial processes.
Human activities (in particular, mining)speed up the movement of toxic inorganic chemicals from rocks and dirt to water. Heavy metals are the biggest concern including elements such as mercury, lead, cadmium and nickel all of which can be highly toxic in minute quantities.
Soils of arid climates often have high concentrations of soluble salts including toxic selenium and arsenic. Irrigation drainage of arid soils can mobilize these substances. Non-toxic such as sodium chloride (table salt) can also be mobilized by irrigation and can reach surface levels that are toxic to animals and plants.
Acids are released as by-products of industry and especially coal mining. Sulfur compounds in coal react with oxygen and water to make sulfuric acid. Acid rain is increasing in the amount of surface-water systems it effects. Acids leach aluminum and other elements from rocks and soil resulting in damage to living organisms.

24. Organic Chemicals
Thousands of natural and synthetic organic chemicals are used to make pesticides, plastics, pharmaceuticals, pigments, etc.
Two most important sources of toxic organic chemicals in water are:
Improper disposal of industrial and household wastes.
Runoff of pesticides from high-use areas.
Fields, roadsides, golf courses
Perhaps the most famous of organic chemicals is DDT and we earlier covered its implications on birds with respect to lower viable reproductive rates. Chlorinated hydrocarbons accumulate in the fat of fish, in fish-eating birds and in humans causing health problems.

25. Sediment
Human activities have accelerated erosion rates in many areas.
Cropland erosion contributes about 25 billion metric tons of suspended solids to world surfaces each year.
Sediment can either be beneficial (nourish floodplains) or harmful (smother aquatic life).
Sediment fills lakes, obstructs shipping channels, clogs hydroelectric turbines and makes water purification harder. Sediment is the largest source of water pollution in the U.S. Sediments smother gravel beds where insects seek shelter and fish lay eggs.

26. Thermal Pollution
Raising or lowering water temperatures from normal levels can adversely affect water quality and aquatic life.
Oxygen solubility in water decreases as temperatures increase.
Species requiring high oxygen levels are adversely affected by warming water.
Industrial cooling often uses heat-exchangers to extract excess heat, and discharge heated water back into original source.
Thermal Plume
Produce artificial environments which attract many forms of wildlife.
Effluent from cooling plants (especially power plants) changes water temperature, and this change has a negative impact on aquatic life. Water temperatures are generally more stable than air, and so abrupt changes in water temperatures disrupts biological systems where aquatic organisms are not adapted to such temperature ranges. Altering vegetation and runoff patterns can also cause thermal pollution.
Warm water plumes from power plants attract fish and birds in cold weather. This can be fatal, however, as shown with the endangered Florida manatee. The manatees use the thermal plumes as winter refuge, but if the power plants shut down, the manatees die from themal shocks

27. Part 7: Water Quality Today
This figure shows the percent of water quality impaired U.S. rivers in 1998 (U.S. EPA). It's important to notice that in some cases the percentages seem more a function of political boundaries then they are likely of reality, as this information is reported by states voluntarily. According to this data, Washington State is among the least polluted states in the United States. The State of Mississippi is by far the most polluted. It is a known fact that Washington State has suppressed the release of information on mercury contamination in the upper reaches of the Columbia River. Also, there are different standards by which states determine whether water is impaired in quality; however, it's obvious from this figure that water quality impairment is a serious issue in U.S. rivers.

28. Groundwater and Drinking water Pollution
About half the US population, and 95% of rural residents, depend on underground aquifers for drinking water.
For decades, groundwater was assumed impervious to pollution. It was considered the gold standard for water quality.
An estimated 1.5 million Americans fall ill from fecal contamination annually.
Cryptosporidium outbreaks
The EPA estimates that 4.5 trillion liters of contaminated water seep into the ground in the U.S. every day. A gasoline additive (MTBE), a suspected carcinogen, is present in many urban aquifers. In agricultural areas, fertilizers and pesticides commonly contaminate aquifers and wells.

29. Groundwater Pollution
Pollution of ground water is a serious water pollution issue that is largely out of sight. Pollution that seeps into the soil is gone as far as the people that created it are concerned; however, if it moves through that soil it can eventually contaminate groundwater. This polluted groundwater might be the source of drinking, industrial, or irrigation water.
This figure shows the many potential sources of groundwater pollution. Note that the source of groundwater pollution, like other types of water pollution, is not necessarily in same place as the source of the polluted water. This is because the water moves laterally underground just as it does above ground.
There is a very interesting recycling technique that millions of people in the U.S. practice. When a home relies on a well for its drinking water, it may also rely on an on-site sewage treatment of wastewater. This treated water is likely to be unknowingly recycled. Basically, water used in the home is introduced into the field adjacent to the home. This wastewater leaches through the soil and reaches the water table; then, the water is pumped through the home's well and reutilized by the people living in the home. Protection of ground water quality in Washington State from pollution is one of the state's highest priorities environmentally. Washington State has a policy of no net degradation of groundwater within the state.

30. Progress and Problems in Other Countries
Sewage treatment in wealthier countries of Europe generally equal or surpass the US.
In Russia, only about half of the tap water supply is safe to drink.
In urban areas of South America, Africa, and Asia, 95% of all sewage is discharged untreated into rivers.
Two-thirds of India's surface waters are contaminated sufficiently to be considered dangerous to human health.
The situation in most of the undeveloped world is very different than in the U.S., Canada, and most of the developed world. This slide shows a slum in Haiti. It not only looks bad, but it is deadly in many different ways. The water in the ditches is likely filled with toxic and infectious materials. Health risks to humans under these conditions are very high. In particular, infant mortality is almost always extremely high under these conditions.
Is easy to talk about people in these situations as being uneducated and backward. It is very difficult, however, for people dealing with acquiring the very necessities of life to think about the impacts of water quality on others. In the U.S., we take clean water for granted, as we have any number of professionals protecting the quality of our water. There are no such professionals protecting surface water quality in this scene in Haiti.

31. Part 8: Pollution Control
Nonpoint Pollution Sources and Land Management
Reduce nutrient loading thru land use regulations
Source reduction is cheapest and most effective way to reduce pollution. To work society must get public and business leaders to avoid producing or releasing substances into the environment.
Studies show as much as 90% less road salt can be used without significantly affecting winter road safety.
Soil Conservation
Banning phosphate detergents
Sewage Treatment
Remediation
The most effective and most cost-effective way of pollution control is to avoid having the pollution produced and released in the first place. This is called source reduction. Once the pollutants have been released into the environment, it normally takes much more money to clean that pollution from the environment. The benefit of such an unnecessary clean up to the environment is lower. In particular, where potential pollutants can be collected and recycled or reused, money can actually be made in the process of preventing pollution.
For instance, it is a nearly universal practice in the photography business to include silver traps that removed the saw silver from waste water produce during photographic development. Prior to the development and use of these traps, millions of dollars worth of dissolved silver contaminated water supplies. Soluble silver is highly toxic.
The banning of DDT as an insecticide in the U.S. has reversed the negative impacts this pesticide caused on the top food chain predators. Alternative pesticides were developed that did not show these negative impacts, but still control the same insect pests. These might not have been developed as quickly if DDT was not banned. Major efforts toward pollution control presently include efforts to limit nonpoint source pollution through land management practices. Other current approaches to remove pollution include adding more sewage treatment facilities to smaller municipalities and remediation of polluted sites.

32. Sewage Treatment Rationale
More than 500 pathogenic bacteria, viruses, and parasites can travel from human or animal excrement through water.
Natural Processes
In many areas, outdoor urination and defecation is the norm.
When population densities are low, natural processes can quickly eliminate waste.
Artificial Wetlands Are a Low Cost Method
Natural water purification
Effluent can be used to irrigate crops or raise fish for human consumption.
The rationale for continuing to improve on sewage treatment procedures and number of facilities is unquestionable. If for no other reason, the large improvement in water quality has resulted in a massive drop in mortality rates in developed countries during the 20th century. Many less developed areas, however, cannot afford or operate high technological water purifying facilities. In such areas, natural systems might be used to clean water. In fact, at low population densities, natural processes quickly eliminate wastes.
As water infiltrates soil and moves through wetlands, it is also purified. Recently, artificial wetlands have been developed as an inexpensive means of purifying water. Similarly, forest soils clean water of organic compounds and pathogens. Wetlands, in particular, have become a partial solution to cleaning water for areas where there is currently not enough money or know-how to develop sewage treatment facilities.

33. Municipal Sewage Treatment
Primary Treatment - Physical separation of large solids from the waste stream.
Secondary Treatment - Biological degradation of dissolved organic compounds.
Effluent from primary treatment transferred into trickling bed, or aeration tank
Effluent from secondary treatment is usually disinfected (chlorinated) before release into nearby waterway.
Tertiary Treatment - Removal of plant nutrients (nitrates and phosphates) from secondary effluent.
Chemicals, or natural wetlands.
In many US cities, sanitary sewers are connected to storm sewers.
Heavy storms can overload the system, causing by-pass dumping of raw sewage and toxic runoff directly into watercourses.
To really get sewage water drinkable, fishable and suitable for natural systems, a 3 step treatment process is required (primary, secondary and tertiary). A problem in many cities, including Seattle, is that sewer pipes are often incorporated into drains for precipitation runoff. When floods occur, these systems overflow and the sewage is often dumped untreated into lakes, rivers and streams.

34. Sewage Treatment
This figure shows the processes of a typical secondary treatment sewage plant such as those at the Renton and West Point plants in Seattle. The first step of treatment is water collection into the treatment plant. As mentioned on the last slide, if systems are not well maintained or with natural disasters overflows occur and raw sewage can be lost from the collection system.
Primary treatment of wastewater includes removing suspended solids in the wastewater by sedimentation and screening. You can imagine what the screened and sedimented material looks like. It is called primary sewage sludge. In Seattle, the primary sludge is further processed by a process called anaerobic digestion, which reduces its potential BOD and stabilizes it.
Secondary treatment includes several potential processes, but typically nutrients and air are added to the waste water to stimulate microbial growth. In the process of growing, microbes absorb dissolved nutrients from the water and many other substances stick to the microbial bodies. These microbial cells are then sedimented from the wastewater and further processed, often by mixing with the primary sewage sludge.
In Seattle's case, chlorine is then added to the water to disinfect it and most of it is discharged into Puget Sound. Some is recycled as cooling water by Boeing, in some misapplied to golf courses, conserving potable water. The environmental impacts of discharge are unknown but likely very small. If the nutrient load that is removed as sewage sludge were discharged the effect would be substantial due to the fertilization of the water.

35. Water Remediation
Containment methods confine liquid wastes in place, or cap surface with impermeable layer to divert water away from the site.
Extraction techniques are used to pump out polluted water for treatment.
Oxidation, reduction, neutralization, or precipitation.
Living organisms can also be used effectively to break down polluted waters.
There are many ways to clean water. Containment methods keep dirty water from spreading. Chemicals may be added to toxic water to precipitate, immobilize or solidify contaminants. Pollutants may be outright destroyed of detoxified by chemical reactions that oxidize, reduce, neutralize, hydrolyze, precipitate the pollutant chemical composition.
Bioremediation is the process of using living organisms to clean contaminated water. This method can be effective and cheap. Wetlands are a general type of bioremediation. A small flowering plant called duckweed (lemna spp.) is used to remove organic nutrients from water. The duckweed can also be harvested and used as feed, fuel or fertilizer.

36. Part 9: WATER LEGISLATION
Clean Water Act (1972)
Goal was to return all U.S. surface waters to "fishable and swimmable" conditions.
For Point Sources, Discharge Permits and Best Practicable Control Technology are required.
Set zero discharge for 126 priority toxic pollutants.
Areas of Contention
Draining or Filling of Wetlands
Many consider this taking of private land.
Un-funded Mandates
State or local governments must spend monies not repaid by Congress.
1972 was a benchmark year for the improvement of water quality. It was this year that the first Clean Water Act was passed. This initial act has been followed by an increasing awareness by U.S. politicians that sometimes effective legislation is the best and fastest way to solve water pollution and that most Americans want clean water. There is disagreement on what the priorities are and just exactly how we go about getting things right. Chapter 15 will deal with legislation progress and evolution in more detail.