Pollution Flushing Into a Stream.
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The quality of Canada's freshwater and marine areas is affected by three important water pollution problems: toxic substances, excess nutrients, and sedimentation.
Toxic substances from industrial, agricultural and domestic use are some of the main pollutants in our water. These include trace elements, polychlorinated biphenyls (PCBs), mercury, petroleum hydrocarbons, dioxins, furans and some pesticides. Some of these substances don't break down in the environment and can accumulate through the food chain.
These substances enter our water in a variety of ways, including:
- industrial sources such as mining, steel
production, the generation of electricity and chemical production;
- accidents such as oil or chemical spills and
contaminated sites;
- municipal wastewater effluents;
- atmospheric deposition from Mexico, the United
States, Europe and Asia, which is deposited in Canada through rain and
snow;
- and agricultural run-off.
Human activity affects the quality of water resources throughout the country. Threats to water quality come from municipal wastewater discharges (sewage, combined sewer overflow, and stormwater runoff), effluent from septic systems, industrial effluent, waste from intensive livestock operations, agricultural runoff, and the deposition of atmospheric pollution.
Municipal wastewater discharges represent one of the largest sources of pollutant releases by volume to Canadian waters. Industries across Canada also discharge hundreds of substances into rivers and lakes daily. The impact of these discharges depends on the nature of the substances and the volumes released.
The National Pollutant Release Inventory (NPRI) data for the 2000 reporting year was published on the Internet on November 28, 2001. This is the most recent NPRI data set available. Below you will find a table of the top ten NPRI reported substances released to surface water for 2000. Although these substances are released in the largest quantities, they do not necessarily constitute the greatest risk to the receiving surface water. To find information on risks related to these substances, visit the NPRI-related links section for a list of Web sites.
Top Ten NPRI Reported Substances Released to Water for 2000
|
Substance Name |
CAS # |
Water Discharge (tonnes) |
Water spills (tonnes) |
Water leaks (tonnes) |
Total Water Releases (tonnes) |
Number of Facilities reporting |
|
Ammonia (Total) |
NA - 16 |
23511.749 |
12.719 |
0 |
23524.468 |
189 |
|
Nitrate ion in solution at pH >= 6.0 |
NA - 17 |
18935.441 |
0 |
0 |
18935.441 |
84 |
|
Methanol |
67-56-1 |
992.451 |
0 |
6.245 |
998.696 |
52 |
|
Manganese (and its compounds) |
NA - 09 |
955.010 |
0 |
0 |
955.010 |
77 |
|
Zinc (and its compounds) |
NA - 14 |
253.955 |
0.512 |
0 |
254.467 |
97 |
|
Copper (and its compounds) |
NA - 06 |
100.593 |
0.748 |
0.001 |
101.342 |
63 |
|
Ethylene glycol |
107-21-1 |
17.019 |
6.482 |
41.052 |
64.553 |
12 |
|
Chlorine |
7782-50-5 |
56.237 |
0 |
0.220 |
56.457 |
18 |
|
Sulphuric acid |
7664-93-9 |
33.621 |
5.167 |
0 |
38.788 |
6 |
|
Nickel (and its compounds) |
NA - 11 |
34.943 |
2.866 |
0 |
37.809 |
33 |
Minimizing or avoiding the creation of pollutants and wastes can be less costly and more effective in protecting the environment than treating them, or cleaning them up after they have been created. Environmental protection activities can be seen as a hierarchy of practices, arranged in order of preference, with pollution prevention at the top. Approaches that anticipate and prevent the creation of pollutants and waste are preferred to other methods such as treatment, re-use and recycling. While these methods are still important elements in our overall environmental protection efforts, even the best waste management practices are not the same as avoiding its creation it in the first place.
In collaboration with many sectors of society, pollution prevention is being achieved through:
- policies and legislation
- guidelines and regulations
- codes and standards
- management systems
- voluntary programs
- reporting mechanisms
- information and training
- technology, research and pilot projects
The federal government is playing a leadership role working with all provinces and territories, through the Canadian Council of Ministers of the Environment (CCME), to ensure our understanding and knowledge of threats to water quality is shared, and strategies to reduce or eliminate impacts can be put in place by individual jurisdictions. Therefore, Canada is promoting the multi-barrier approach to protecting water quality from source to tap. This approach identifies the tools needed to reduce public health risks at every stage of the drinking water system (source water protection, drinking water treatment, and drinking water distribution systems). In addition, all governments are collaborating on accelerating Canadian drinking and source water quality guidelines development, linking monitoring networks across the country to better share information on water quality issues and trends, and providing Canadians with information on the quality of their water. For more information on the multi-barrier approach, read the EnviroZine article on Source to Tap - Protecting Canada's Water or visit the CCME Source to Tap Web site.
Related Links
Source to Tap - Protecting Canada's Water (EnviroZine article)
CCME Source to Tap Web Site
Freshwater Web Site - Water Pollution
Freshwater Web Site - Water Quality
Sustaining the Environment and Resources for Canadians
National Water Research Institute: Threats to Sources of Drinking Water and Aquatic Ecosystem Health in Canada
Tracking Key Environmental Issues: Air and Water
National Pollutant Release Inventory (NPRI)
Control water pollution with your own rain garden - June 2002 - ENN.com
Jeter l'eau par les fenêtres - July 2002 Cybersciences.com (French only)
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