Clean Water – Life Depends on It!
- Canada: A Water Paradise?
- What Determines Water Quality?
- Aquatic Ecosystems
- How Do We MeasureWater Quality?
- Human Health and Water Quality
- The Pollution Problem
- Controlling Water Pollution
- What Can I Do to Improve Water Quality?
- The Choice We Make Now
"Pure water is the best of gifts that man to man can bring"
- Spectator, July 30, 1920
What's in a glass, a sink, a river full of water?... A refreshing drink... a cleansing wash... an invigorating swim... a home for plants, insects, fish, birds and mammals. It all depends on the water quality.
We tend to think of water in terms of a particular purpose: is the quality of the water good enough for the use we want to make of it? Water fit for own use may be unfit for another. We may, for instance, trust the quality of lake water enough to swim in it, but not enough to drink it. Along the same lines, drinking water can be used for irrigation, but water used for irrigation may not meet drinking water standards. It is the quality of the water which determines its uses.
Scientists, on the other hand, are interested in other aspects of water quality. To them quality is determined by the kinds and amounts of substances dissolved and suspended in the water and what those substances do to inhabitants of the ecosystem. It is the concentrations of these substances that determine the water quality and its suitability for particular purposes.
Drinking water, for example, is regulated by guidelines stringent enough to protect human health. Lack of such guidelines can lead to a variety of health problems. It has been estimated, for example, that contaminated water and poor sanitation cause 30 000 deaths around the world daily -- the equivalent of 100 jumbo jets crashing every day!
Water is the lifeblood of the environment, essential to the survival of all living things -- plant, animal and human -- and we must do everything possible to maintain its quality for today and the future.
The Great Lakes: chemical hot spot
Over 360 chemical compounds have been identified in the Great lakes. Many are persistent toxic chemicals – alkylated lead, benzo(a)pyrene, DDT, mercury and mirex – potentially dangerous to humans and already destructive to the aquatic ecosystems.
For example, various species of fish now suffer from tumours and lesions, and their reproductive capacities are decreasing. Populations of fish-consuming birds and mammals also seem to be on the decline. Of the ten most highly valued species of fish in Lake Ontario, seven have now almost totally vanished.
Canada: A Water Paradise?
Here in Canada we are fortunate. We have extensive supplies of water. Our pristine rivers and lakes filled explorers and settlers with a sense of majesty and awe. Today, they continue to impress Canadians and visitors alike. Yet under the pressures of human development, many of these waters are losing their un-spoiled quality.
It is no wonder. We dispose of human wastes, animal wastes and chemical substances into the environment at such a rate that even some of the largest lakes and river systems -- the Great Lakes and the St. Lawrence River, for example -- are having serious difficulty cleansing themselves and sustaining life.
What Determines Water Quality?
The water of even the healthiest rivers and lakes is not absolutely pure. All water (even if it is distilled) contains many naturally occurring substances -- mainly bicarbonates, sulphates, sodium, chlorides, calcium, magnesium, and potassium (total dissolved solids). They reach the surface and groundwater from:
- soil, geologic formations and terrain in the catchment area (river basin);
- surrounding vegetation and wildlife;
- precipitation and runoff from adjacent land;
- biological, physical and chemical processes in the water;
- human activities in the region.
In nature nothing exists alone. Living things relate to each other as well as to their non-living, but supporting, environments. These complex relationships are called ecosystems. Each body of water is a delicately balanced ecosystem in continuous interaction with the surrounding air and land.
Whatever occurs on the land and in the air also affects the water. If a substance enters a river or lake, the water can purify itself biologically -- but only to a degree. Whether it is in the smallest stream or lake -- or even in the mighty oceans -- the water can absorb only so much. It reaches a point where the natural cleaning processes can no longer cope.
How does water clean itself?
Water is purified in large part by the routine actions of living organisms. Energy from sunlight drives the process of photosynthesis in aquatic plants, which produces oxygen to break down some of the organic material such as plant and animal waste. This decomposition produces the carbon dioxide, nutrients and other substances needed by plants and animals living in the water. The purification cycle continues when these plants and animals die and the bacteria decompose them, providing new generations of organisms with nourishment.
Unfortunately, there are many toxic substances which are affected only slowly, or not at all, by this and other processes. These are called persistent (see Water quality pollutants) and are of great environmental concern.
How Do We Measure Water Quality?
To identify the substances present in a stream or lake, scientists collect samples of the water, of living organisms, and of suspended and bottom sediments. Technicians then analyze these samples in a laboratory with specialized instruments and procedures. Certain measurements such as temperature, dissolved oxygen, turbidity and conductivity can be taken in the field with portable equipment.
Today's analytical laboratory instruments -- with such high-tech names as "plasma emission spectrometer" (for analysing metals) and "gas chromatograph-mass spectrometer" (for analysing pesticides, PCBs dioxins, and other organic compounds) -- bear little resemblance to the test-tube and gas burner laboratories of the 1950s.
Nowadays the analysis of water and sediment samples detects more substances than a decade ago, partly because there are more substances present in water, but also because of improved analytical instruments and consequently lower detection limits. State-of-the-art analytical instruments can detect down to one part per trillion of some substances -- comparable to tracing one thousandth of a teaspoon of salt dissolved in an olympic-size swimming pool.
The acidity of a water sample is measured on a pH scale. This scale ranges from 0 (maximum acidity) to14 (maximum alkalinity). The middle of the scale,7, represents the neutral point. The acidity increases from neutral toward 0.
Because the scale is logarithmic, a difference of one pH unit represents a tenfold change. For example, the acidity of a sample with a pH of 5 is ten times greater than that of a sample with a pH of 6. A difference of 2 units, from 6 to 4, would mean that the acidity is one hundred times greater, and so on.
Normal rain has a pH of 5.6-- slightly acidic because of the carbon dioxide picked up in the earth's atmosphere by the rain.
Human Health and Water Quality
In Canada we are lucky to have plentiful supplies of good drinking water sources. Water-related illnesses -- typhoid fever, cholera, dysentery -- are almost unknown in this country today. Waste and wastewater treatment, the development and enforcement of drinking water guidelines, public health practices and education -- all have resulted in a decrease in water related illnesses in Canada. Developing nations are less fortunate: 80% of their diseases are water-related.
The price Canadians must pay to prevent water-borne disease is constant vigilance against bacterial contamination. Periodic beach closures and local epidemics are evidence that the battle is never won. These problems underscore the need for maintaining strict control over water quality and for improving water and wastewater treatment.
Of serious concern today are the toxic chemicals that enter our waters from many different sources, including industry, agriculture and the home. Little is known about the effects of these toxic substances on human health; often the effects do not become noticeable for long periods of time, and it is difficult to distinguish them from the effects of other factors that impact on our day-to-day life (e.g., nutrition, stress, air quality). Much more remains to be done to control toxic chemical pollution. Meanwhile, we can all contribute to the prevention of water pollution by not abusing the water or the land. (See What can I do to improve water quality?)
A sampling of water quality facts
The Pollution Problem
It is easy to dispose of waste by dumping it into a river or lake. In large or small amounts, dumped intentionally or accidentally, it may be carried away by the current, but will never disappear. It will reappear downstream, sometimes in changed form, or just diluted. Freshwater bodies have a great ability to break down some waste materials, but not in the quantities discarded by today's society. This overload that results, called pollution, eventually puts the ecosystem out of balance.
Sometimes nature itself can produce these imbalances. In some cases, the natural composition of the water makes it unfit for certain uses: e.g., water flowing in the highly saline terrain of the prairies or gushing from highly mineralized springs in some parts of the country cannot sustain fish populations.
But most often our waterways are being polluted by municipal, agricultural and industrial wastes, including many toxic synthetic chemicals which cannot be broken down at all by natural processes. Even in tiny amounts, some of these substances can cause serious harm.
The Great Lakes, the Fraser River, and the St. Lawrence River are and continue to be seriously contaminated by such toxic chemicals.
We have polluted our way to wealth... at the expense of the environment.
Toxic chemicals: the legacy of a chemical society
We are a "chemical" society, using hundreds of chemicals in our normal daily activities: washing, eating, house-cleaning, tending the lawn and garden, and driving. Of the almost 10 million chemicals known today, approximately 100 000 chemicals are used commercially.
Most toxic chemicals are discharged directly into our waterways as waste, but many also enter the water after everyday use in the home, agriculture and industry. They constantly change the chemical composition of our waters. One way is seepage: the chemicals soak through the earth into the groundwater from waste disposal sites and agricultural lands, for example. Another way is runoff: the chemicals are washed into bodies of water from the land where they were used or spilled, or from the air into which they were emitted.
The chemicals can cause problems with the taste, odour and colour in water. Fish and wildlife can experience reduced fertility, generic deformities immune system damage, increased incidence of tumours, and death.
Many of the chemicals that enter the water are, even in minute amounts, toxic to human, plant and animal life. Pesticides, PCBs, and PCPs (polychlorinated phenols) are typical examples. Pesticides are used in agriculture, forestry and homes. PCBs although no longer used in new installations, are still found as insulators in older electrical transformers, and PCPs can be found in wood preservatives. The very qualities which make them desirable for use -- toxicity and persistence, for instance -- make them so harmful to the environment.
The effects of pollution
Pollution is not always visible. A river or lake may seem clean, but still be polluted. In groundwater, on which over one quarter of all Canadians rely for their water supply, pollution is especially difficult to discern. Nor are the effects of pollution necessarily immediate; they may take years to appear.
When pollution makes water unsuitable for drinking, recreation, agriculture and industry, it eventually also diminishes the aesthetic quality of lakes and rivers. Even more seriously, when contaminated water destroys aquatic life and reduces its reproductive abilities, it eventually menaces human health. Nobody escapes the effects of water pollution.
Water quality pollutants
These compounds can be broken down by chemical reactions or by natural bacteria into simple, non-polluting substances such as carbon dioxide and nitrogen. The process can lead to low oxygen levels and eutrophication if the pollution load is high. But this damage is reversible.
Persistent (degrade slowly)
This is the most rapidly growing type of pollution and includes substances that degrade very slowly or cannot be broken down at all; they may remain in the aquatic environment for years or longer periods of time. The damage they cause is either irreversible or reparable only over decades or centuries.
These are examples not of chemical pollution, but of physical pollution which interferes mainly with the usability and/or aesthetic appeal of the water. In certain cases, thermal pollution can kill fish.
The long-range transport of airborne pollutants: what goes up must come down
On a daily basis, human activities -- industrial, agricultural and residential -- cause vast quantities of natural and synthetic chemicals to be emitted into the atmosphere. Once released, the substances are dispersed throughout the globe by air currents that know no boundaries -- provincial or international. This phenomenon is known as long-range transboundary air pollution (LRTAP).
Over time, these emissions expose human beings, wildlife and resources to diverse quantities and mixtures of air pollutants. The resulting harm is difficult to evaluate, since it occurs over varying time frames and over vast areas having differing degrees of sensitivity. The reversibility of the damage is not yet well understood.
Some of the chemicals in the atmosphere are rendered harmless through exposure to sunlight, but others are extremely persistent, surviving and circulating around the earth for as long as months or years. They reach our water systems through dry or wet deposition.
Acid rain, one of the most publicized LRTAP phenomena, originated with emissions from coal-fired generators, non-ferrous metal smelters, petroleum refineries, iron and steel mills, pulp and paper mills, and from motor vehicle exhaust. The released sulphur dioxide and nitrogen oxides are converted to sulphuric and nitric acids in the atmosphere. These acids return to earth through wet sulphate and/or nitrate deposition (including rain, snow and fog).
In Canada, the major sources of sulphur dioxide emissions are non-ferrous metal smelters, followed by coal-fired generators. Motor vehicles and, to a lesser extent, coal-fired generators, are the major sources of nitrogen oxides. About half the wet sulphate deposition in eastern Canada is estimated to come from the United States, while about ten percent of the deposition in the northeastern United States comes from Canada.
The damage caused by acid rain deposition occurs in environments that cannot tolerate acidification. Many species of fish, insects, aquatic plants and bacteria develop reproduction difficulties. Some even die. The decline in the population of any of these aquatic organisms affects the food chain. Dwindling populations of insects and small aquatic plants and animals are especially serious because the entire food chain is affected.
Controlling Water Pollution
Since water plays such a vital role in life on earth, good quality water is a precious resource. Often water quality is more important than water quantity. The quality of a the water affects the use we make of it, but the reverse is also true. Once we have used the water, we affect its quality.
This circular process indicates that the traditional habit of discharging untreated sewage and chemical wastes directly into rivers, lakes, estuaries or oceans for eventual "assimilation" into the environment is no longer acceptable, either technically or morally.
The explosion in human population and industrial activities, and the rate at which new chemicals and products are being developed and used -- pose a global environmental threat. The natural decay processes in water bodies can no longer cope with these loads.
The approach to controlling pollution depends on:
- the type of pollutant
is it degradable? persistent?
is it a metal? pesticide? dioxin? PCB?
- the source
does it come from an industrial pipe?
a farmer's field? the atmosphere?
- the effects
is it harming fish? birds? plants? humans?
Accelerated aquatic plant growth: too much too fast
The growth and reproduction of aquatic plants is stimulated by eutrophication, a natural process which, over geological time, turns a lake into a bog and eventually into land. But today, in many places, this process is tremendously accelerated by high concentrations of phosphorus and nitrogen (from fertilizer, for example) which enrich the water with nutrients, causing the aquatic plants to bloom. As the plant growth explodes, it chokes off the oxygen supply normally shared with other organisms living in the water. When the plants die, their decomposition uses up even more oxygen. As a result, fish suffocate and die, and bacterial activity decreases.
Yet if phosphorus and nitrogen inputs are reduced or stopped, the system can recover by itself. In the late 1960s, Lake Erie experienced such an extreme case of eutrophication that fish were dying and the decomposing algae, washed up on bathing beaches, had to be removed with bulldozers.
The phosphorus (phosphate) in laundry detergents washed into the lake was the main culprit. A law was passed to reduce the substance, and in 1972 laundry detergent phosphate contents were cut by approximately 90%. Lake Erie has since made a remarkable recovery.
Water quality objectives and guidelines
In Canada, governments use various measures to protect water quality, among them guidelines and objectives. The two measures are similar in that both describe how much of a substance we, as a society, will tolerate in water. But guidelines and objectives are arrived at and applied differently.
Water quality guidelines are scientifically determined and indicate the maximum allowable concentration of substances for aparticular water use such as livestock watering or swimming. These national guidelines serve as the targets for environmental protection.
Water quality objectives, on the other hand, specify the concentrations of substances permissible for all intended water uses at a specific location on a lake, river, or estuary. The objectives are based on the water quality guidelines for the uses at that location, as well as on public input and socio-economic considerations.
Water quality guidelines and objectives not only protect water users and the environment, they also promote sustainable water management strategies.
Ideally, polluting contaminants should be prevented from entering the water. At the most, in some circumstances, they can be allowed only in low concentrations. All provinces and territories in Canada have pollution control regulations. In deciding which substances to control, and to determine their concentrations and how they may enter the environment, a number of questions have to be asked, including:
- what are the sources, amounts and effects of various substances?
- what happens to them and what do they do after they have entered the water? do they change? to what?
- where do the substances end up?
- can they be prevented from reaching the water body or removed by treatment?
An example of a substance successfully regulated to reduce pollution is the phosphate found in laundry detergents (see Accelerated aquatic plant growth). The Canadian Environmental Protection Act (CEPA) regulates many more substances that have a deleterious effect on the environment.
Technology can be used in many cases to reduce or eliminate substances that may be harmful to the environment. Sewage treatment plants, properly operated and maintained, are a means of removing many toxic substances from wastewater and returning the treated water to a river or lake without causing harm downstream. Water treatment plants can take river or lake water and make it fit for drinking.
But what happens when contaminants are not removed, even by the most modern water treatment methods? They may be present only in minuscule quantities, but because they are persistent, they can build up to very harmful levels. In such cases, we can protect future generations and the ecosystem as a whole in only one way: preventing the chemicals from entering the water system.
Be a responsible consumer – it makes sense
Something all of us, as individuals, can do to protect water quality and the environment is to recycle products that are not degradable such as glass, cans and motor oil. Many municipalities in Canada have recycling programs.
Choose non-hazardous products. Most household chemical products and pesticides sold in Canada have warning labels. These labels tell whether the product is flammable, poisonous, corrosive or explosive. Proper disposal of these products is important to ensure water quality is not affected.
What can I do to improve water quality
In the face of this planet's overwhelming environmental problems, each individual effort to protect water quality is vital. Together, individual actions can and do make a difference to water quality and the environment as a whole. You can start by taking the following actions:
Avoid hazardous household products
Most proprietary household chemicals are safe to use and are environmentally friendly, when used according to the directions on the package. However, some have a harmful cumulative effect on the environment when they are over-used or incorrectly disposed of.
Don't misuse the sewage system
Don't throw waste down the drain just because it's convenient. Toxic household products can damage the environment and return to us through water and food.
Don't use pesticides or other hazardous materials in your garden
Adopt alternative pest control methods, such as:
Don't dump hazardous products into storm drains
Storm drains empty directly into nearby streams in many areas. The contents of storm sewers are generally not processed at sewage treatment facilities and can therefore do immediate harm to fish and wildlife. Beach closures are a typical example of storm water pollution in many communities.
Don't forget about water quality – even when you're having fun
Take further action
There is more you can do!
The Choice We Make Now
As we enter the 21st century, we find ourselves at a critical point and with very little time -- years, not generations -- in which to undo environmental damage and bring water resources to the point at which they can maintain themselves naturally. We must now think in terms of sustainable development: using and managing resources and the environment in such a way that they both maintain a strong economy and preserve a healthy environment today and in the years to come.
All of us must do our part -- government, industry, public interest groups, individuals -- at home, at school, at the workplace, while working, while playing, while traveling. It is time to re-examine our values, make thoughtful choices, and adjust our lifestyles to give more consideration to the environment. This includes changing our water use habits in ways that will help the resource sustain itself and maintain its quality.
It is important for each one of us to act -- not only for ourselves and our children, but for future generations and for the other living things sharing the earth with us.
Freshwater Series A-3
Note: A resource guide, entitled Let's Not Take Water For Granted, is available to help classroom teachers of grades 5-7 use the information from the Water Fact Sheets.
Published by authority of the Minister of the Environment
© Her Majesty the Queen in Right of Canada, 1992
- Date Modified: