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Water Resources
Water is essential for all life. This section explains what water is and where it is found on our planet.
Q3.61
What is water? Pure water is a substance made up of molecules
containing one atom of oxygen and two atoms of hydrogen (H2O). It is without
colour, taste, or smell, turns to solid at OoC, and to vapour at 100oC. It is an
extremely good solvent.
Q3.62
Why is water important? Water is the essential element of all
life. Some very simple organisms can survive without oxygen, but none can
survive without water. Our own bodies are two-thirds water. Water plays
important roles in climate, element cycles, and ecosystems. The health of all
species of plant and animal life is critically dependent on the quality of the
water resources that sustain them.
Q3.63
What is groundwater? Groundwater is water found in the tiny
spaces between soil particles or in cracks in bedrock, much like the water in a
sponge. The underground areas of soil or rock where substantial quantities of
water are found are called 'aquifers'. These aquifers are the source of wells
and springs. It is the top of the water in these aquifers that form the 'water
table'.
Q3.64
How much freshwater does Canada have? Canada has about 9% of
the world's renewable freshwater supply, compared to 18% for Brazil, 13% for the
USSR, 9% for China, and 8% for the U.S. The Great Lakes, which straddle the
Canada-U.S. border, are the largest system of fresh surface water on earth.
Did you know?
Thirty percent of the world's fresh water is tied up
in the polar ice caps.
Q3.65
Should we worry about how water is used? Although freshwater
is abundant in Canada, in many areas it is not found in the right quantity or
quality. Approximately 60% of Canada's freshwater drains north, while 90% of the
population lives within 300 km of the Canada-U.S. border. In addition, some
parts of Canada receive very little precipitation. In these areas the
groundwater tends to be salty and unsuitable for many uses. Even in the Great
Lakes basin, some off-lake areas experience periodic and even chronic water
shortages, forcing communities to resort to ground-water 'mining' (i.e., more
water is taken out of underground water supplies than is being put back). In
many of the settled areas of the country, water is extremely polluted and is
either unsuitable for human, animal, and industrial use, or usable only at a
relatively high cost of treatment.
Water Use and Abuse
Canadians use a lot of water. This section looks at where and how we use it, and at what happens to it after it is used.
Q3.66
How do we use water? Water use may be consumptive or
non-consumptive. Most of the water used by farming, industry, and domestic users
is consumptive, meaning that less water is returned to the source than was taken
out. Hydroelectric power generation, shipping, and water-based recreation are
examples of non-consumptive uses of water.
Q3.67
Do Canadians waste water? Yes, many of us do. Canadians are
the world's second-largest per capita users of water. The average amount of
water used per person per day in Canada is 390 litres. Europeans use close to
half that amount.
focus
On a worldwide basis, agriculture accounts for the largest
amount of water used 73%. Industry uses 21%, while public use accounts for 6%.
However, the pattern of water use varies widely from country to country. For
instance, Egypt devotes 98% of its water to irrigation, whereas in Canada
irrigation accounts, on average, for only 10% of water use. In 1986, Canada's
water withdrawals were used as follows:
thermal power generation 60% manufacturing 19% municipal use 11.2% agriculture 8.4% mining extraction 1.4%
Q3.68
How can I possibly use that much water? Where does it all go?
Toilet flushing uses 40%; showers, baths, and personal use take 35%; dishes and
laundry use 20%, and drinking and cooking account for 5%. in the summer, water
use can increase by 50% as a result of watering lawns and washing cars.
Q3.69
Do we pay the true cost of the water we use? No. Water fees
are charged in urban areas. However, several studies show that revenues from
these fees are not sufficient to cover operational, repair, upgrading, or
expansion costs of water distribution and treatment systems. Since the
difference is covered by other tax money, we end up paying anyway, but the true
price of water is hidden since water fees themselves are so low. This creates
the illusion that water is cheaper than it really is. In addition, the price we
pay for water often does not vary with the amount consumed. In many areas, users
are charged a flat monthly, quarterly, or annual rate in exchange for access to
unlimited amounts of treated water. This means that there is no price incentive
to use water efficiently no matter how much you use, you pay the same amount.
Q3.70
Where does our tapwater come from? About 26% of Canada's
population relies entirely on groundwater for its drinking water (up from 10% in
1960). The rest of the population obtains water from lakes and rivers. In
cities, water is distributed through a series of pipes connected to a municipal
water supply system that typically has intake, treatment, storage, and
distribution components. In many rural areas, water is taken directly from
groundwater via wells. In several regions of Canada the north, and some rural
areas where wells tend to go dry water is delivered by trucks.
Q3.71
Where does wastewater go? Wastewater is collected in sewers
an either taken to a sewage treatment plant or else discharged directly into a
river, lake, or ocean. When sewage is treated, the resulting sludge is used in
agriculture as a soil conditioner, disposed of in landfill sites, or
incinerated.
Q3.72
How is wastewater treated? There are three different levels
of wastewater treatment. Primary treatment involves the mechanical removal of
solid material (particles that will float or settle). Secondary treatment is
based on biological processes, by which bacteria degrade the bulk of dissolved
organic matter. Finally, tertiary treatment is a chemical process designed to
remove additional contaminants, such as nutrients, heavy metals, and inorganic
dissolved solids.
Did you know?
The value of Canadian water treatment and delivery
systems has been estimated at $100 billion.
Q3.73
Doesn't all wastewater get treated? No. Some urban areas in
Canada do not have sewage treatment facilities. Even in the areas that do, not
all sewage gets treated. Wastewater treatment takes time, and treatment
facilities can handle only a certain volume in a given period. When the amount
of wastewater being produced in one area surpasses the maximum capacity of the
area's treatment plant (as often happens when heavy or prolonged rains increase
storm sewer wastewater), the excess is simply diverted untreated into a lake or
river. In addition, not all wastewater treatment plants have facilities to carry
out all three levels of treatment. Thus, even treated water is not necessarily
stripped of pollutants. Finally, untreated sewage flows into waterways from many
cottages.
Action Step
With little modification to lifestyle Canadians can
greatly reduce their water consumption. The key is to follow the three R's of
water conservation:
Reduce: Be conscious of the amount of water you use and look for ways to use less.
Repair: Fix leaks a leak of one drop per second wastes 10,000 litres per year.
Retrofit: Adopt or replace water-inefficient fixtures and appliances with the water-saving devices now on the market.
For more suggestions on how to reduce water consumption, please see the action guide.
Did you know?
In 1989, less than 65% of the urban Canadian
population received some form of sewage treatment.
Water Quality
Water quality is one of the most common concerns among Canadians. Much progress has been made since the 1960s, but in many cases there is still room for considerable improvement. This section looks at some of the key issues relating to water quality in Canada.
Q3.74
What determines water quality? Water quality is determined by
the kinds and amounts of substances in the water and what those substances do to
inhabitants of the ecosystem. The water of even the healthiest rivers and lakes
contains many naturally occurring substances mainly bicarbonates, sulphates,
sodium, chlorides, calcium, magnesium, and potassium. What's more, human
activities can pollute rivers and lakes with excessive nutrient enrichment,
persistent toxics, and bacteriological contamination.
Q3.75
Are there different kinds of water pollution? Yes. Water
pollution can be divided into two main categories: non-persistent and
persistent. Non-persistent pollutants are degradable; they can be broken down by
chemical reactions or by natural bacteria into simple, non-polluting substances
such as carbon dioxide and nitrogen. Organic waste is an example of a
non-persistent pollutant. The breakdown of organic waste can lead to low oxygen
levels and 'eutrophication' (see question #3.77), but the damage is reversible.
Organic waste may also contain micro- organisms which are the waterborne agents
of diseases such as cholera, typhoid, and dysentery. Sources of non-persistent
pollution include domestic sewage, fertilizers, some household cleaners, and
some industrial wastes.
Persistent pollutants degrade very slowly or not at all, and so may remain in the aquatic environment for years or decades. Damage from persistent pollutants is either irreversible or reparable only over long periods of time. Examples of persistent pollutants include some pesticides, some leachate components from landfill sites, petroleum, PCBs and dioxins, radioactive material, and metals such as lead, mercury, and cadmium.
Q3.76
Are there other forms of water pollution? Yes. In addition to
chemical forms of pollution, water may be polluted by garbage, foam, and
floating debris physical objects that interfere with the usability or aesthetic
appeal of the water. Water may also be 'polluted' by waste heat released by
industries into water bodies. A rise of temperature of even a few degrees is
enough to interfere with an ecosystem. Warmer water may increase the
susceptibility of aquatic life to parasites, diseases, or toxins.
Q3.77
What is eutrophication? Eutrophication is a process of
nutrient enrichment in bodies of water that stimulates the growth of aquatic
plant life and, over geological time, turns lakes into bogs, and eventually into
land. It occurs naturally with the gradual input of nutrients and sediment
through erosion and precipitation.
Q3.78
Do humans modify this eutrophication process? Yes, we speed
it up. Municipal and industrial effluent, agricultural fertilizer, and soil
erosion caused by poor land-use practices release nutrients, particularly
phosphorus, into rivers and lakes. A minimum concentration of nutrients in
aquatic ecosystems is necessary for plant life, the basis of aquatic food
chains. High nutrient concentrations, however, result in dense growths of
aquatic weeds and algae. These plants compete with other aquatic organisms for
oxygen; when they die, their decomposition uses up even more oxygen. Since
dissolved oxygen is essential to most aquatic life, fish suffocate and die. This
process can radically change the biological community of lakes and rivers,
ruining their recreational value, reducing fish catches, and increasing the cost
of water treatment.
focus
In 1882, 180 people out of every 100,000 in Ontario died of
typhoid, cholera, or other such diseases. The reason? Drinking water intakes
were placed too close to sewer outfalls. The reaction to this first
environmental crisis in the region was to extend water intakes farther into
lakes or further upstream in rivers and, eventually, to chlorinate drinking
water. These measures served to stop epidemics and curb infant mortality.
Q3.79
What is an example of a nutrient-enriched lake? One of the
most infamous examples of human-enhanced eutrophication is Lake Erie. In the
1960s, parts of Lake Erie took on a sickly green hue, as blue-green algae
bloomed in open water. Beaches became covered with green, slimy, rotting masses
of an algae called Cladophora. A precipitous decline in traditional types of
aquatic life led to the suggestion that Lake Erie was 'dying'. In fact, the
composition of life forms was changing as the lake became enriched with
nutrients such as phosphorus, nitrogen, and potassium; algae and bacteria were
replacing fish.
Q3.80
Is this damage reversible? Yes. If nutrient inputs are
reduced to normal levels, water systems can recover. Since the 1970s phosphorus
levels have dropped significantly as a result of a major international effort to
reduce effluent from point sources such as municipal sewage plants and
industries. Massive algal blooms no longer occur in Lake Erie, although oxygen
depletion remains a problem. Despite successes in the Great Lakes basin,
nutrient enrichment of rivers and lakes remains a problem in areas such as the
Prairies.
Q3.81
When is a substance considered toxic? A toxic substance is
one that causes some adverse biological effect in living things. The level of
toxicity of a substance depends upon many conditions, notably the level of
concentration of the substance. Toxicity also depends on how the substance
behaves in the environment, including its ease of transformation into a
non-toxic form, its accumulation characteristics, and its reaction with other
chemicals.
Q3.82
What kinds of effects do toxic substances have on fish and
wildlife? Toxic substances have a wide variety of harmful effects, including
reduced fertility, genetic deformities, immune system damage, increased
incidence of tumours and death.
Q3.83
Are toxic chemicals a recent development? No. Some extremely
poisonous substances, such as chlorine and cyanide, have been used in industry
since the nineteenth century. The toxicity of these substances is immediate and
direct; this has made their management relatively straight-forward, because it
is clear that they must be handled with great caution. However, about 40 years
ago, it became apparent that many chemicals could be toxic even in very small
quantities if exposure to them was sufficiently prolonged. These substances,
such as DDT, and PCBs, are often referred to as the microcontaminants, since
their environmental concentrations tend to be extremely low, relative to
concentrations of other pollutants.
Q3.84
How do small quantities of contaminants exert such harmful
effects? Apart from their intrinsic toxic properties, many of these chemicals
are very stable; they persist in the environment for a long time without
breaking down into less harmful by-products. If an organism's intake of a
persistent chemical exceeds its ability to metabolize or eliminate the
contaminant, the substance accumulates over time in its tissues
(bioaccumulation). Organisms also pass their accumulation of contaminants on to
other creatures when eaten (biomagnification). Plankton with relatively low
concentrations of toxic substances are eaten by fish, which are in turn eaten by
birds and other larger fish. At each stage of this food chain, contaminant
levels increase. Even though concentrations of the contaminant in water may be
so low as to be virtually undetectable, as it passes up the food chain from prey
to predator it is magnified hundreds or thousands of times.
In the Great Lakes, for example, this process led to poor health, reproductive problems, and decreased population size for fish-eating birds such as the Herring Gull. In the early 1970s, waterbirds in the Great Lakes were among the most heavily contaminated in the world. PCB concentrations in Herring Gull eggs were millions of times the levels detectable in water. Following regulations on the use of organochloride pesticides in the 1960s and 1970s and the voluntary reduction in the production of PCBs by its manufacturer in 1971, concentrations of contaminants in these birds have decreased greatly.
Q3.85
Has the situation with respect to toxics in the Great Lakes
basin improved or worsened since the 1970s? In general, the situation has
improved. No new contaminants that fit the criteria of widespread occurrence,
high toxicity, and persistence have been detected in any of the Great Lakes
since the early 1980s. As well, levels of contamination in fish and aquatic
birds have decreased substantially from the high values reported in the 1970s.
This reduction has now levelled off. Since the early 1980s contaminant levels in
wildlife have remained constant, while contaminant levels in fish have
fluctuated around a lower level. In the case of Lake Ontario, concentrations may
be stabilizing at an unacceptably high level. While the scale of the problem
will likely never be as bad as it once was, further decreases in contaminant
levels will require greater effort on the part of all those involved.
Q3.86
How are humans exposed to toxic chemicals? Consumption of
food is the major contaminant route for humans, followed by water and air, which
together account for one quarter of human exposure to contaminants. The purity
of food in turn depends upon the quality of all components of the ecosystem
water, air, and soil.
Q3.87
What are some of the sources of water pollution? Industry.
Toxic chemicals and nutrients are present in the effluents of many
industries.
Sewage. Untreated sewage is a cause of nutrient enrichment, and may
contain disease-causing
bacteria and toxic chemicals.
Urban run-off. Urban run-off is a mixture of lead, salt, oil, and chemical
compounds that washes
off the roads. Some of it enters the city's sewer
system and is treated at sewage treatment plants, but some penetrates to
groundwater, and some flows into waterways untreated.
Agriculture. Fertilizers used on farms can contribute to eutrophication,
and pesticides may
contaminate water with toxic chemicals.
Household products. Some household products contain nutrients such as
phosphorus or toxic
substances.
Q3.88
Does pollution enter water bodies from the air? Pollutants
can enter water bodies from the air, often travelling long distances. On a daily
basis, human activities cause vast quantities of natural and synthetic chemicals
to be released into the atmosphere. These are then dispersed over long distances
by air currents, and eventually deposited over land or water. Since exposure
occurs over vast areas with different sensitivities, and over different time
frames, the potential harm and reversibility of environmental damage are not
well understood.
Q3.89
What is an example of a long-range air pollutant? Acid rain
is perhaps the best known and most widely studied of long-range pollutants. It
results primarily from the combustion fuel in transportation, the production of
electricity from coal and from base-metal smelting, and can cause reproductive
failure in many forms of aquatic life.
Q3.90
Can groundwater be damaged by human activity? Yes. The
seepage of agricultural pesticides into groundwater is currently a problem in
some areas of Prince Edward Island, southern British Columbia, and southern
Ontario. As well, underground storage tanks for petroleum and hazardous waste
can develop leaks as they deteriorate over time. Sewage from poorly maintained
septic tanks and leachate from older landfill sites are also causes for concern.
Because groundwater flows so slowly, contaminants are not carried away and
diluted as rapidly as they are in rivers or oceans. It also purifies itself very
slowly since the microbes that normally break down organic pollutants require
oxygen, and groundwater is cut off from the atmosphere. For these reasons,
groundwater may remain contaminated for centuries.
Q3.91
Is the water that we drink safe? There has been much concern
recently over the quality of our drinking water, leading some people to use
bottled water instead of tap water. While there have been no long-term,
comprehensive studies to confirm or refute this perception, several regional
studies indicate that tap water is indeed safe, even in the lower Great Lakes
region. For most of the chemicals detected in surveys, concentrations have been
so low hundreds or thousands of times below health guidelines that their
presence in drinking water is not believed to present a significant risk to
health.
Action Step
There are a number of ways in which individuals can
contribute to the health of aquatic ecosystems.
