This publication was prepared by the Indicators and Reporting Office of Environment Canada, under the direction of Wayne Bond. The research, writing, data analysis, and data interpretation were undertaken primarily by Vincent Mercier and Lara Cooper of the Indicators and Assessment Office. The report is partly based on the 1997 Environment Canada science assessment entitled “Review of the Impacts of Municipal Wastewater Effluents on Canadian Waters and Human Health”, which was authored by Martine Allard, Judy Busnarda, Patricia Chambers, Catherine Jefferson, Robert Kent, John Lawrence, Jiri Marsalek, Steve Munger, Mark Servos, Sherry Walker, and Mike Wong. The technical writer for the present report was David Francis of Lanark Communications, and the technical editor was Marla Sheffer.
We would like to extend our appreciation to the following people, all Environment Canada representatives, for having provided their expert advice on the many drafts of the report: Martine Allard, Donald Bernard, Pierre-Yves Caux, Patricia Chambers, Murray Charlton, Maureen Copley, Richard Dalcourt, Connie Gaudet, Paul Gavrel, Peggy Hallward, Jim Haskill, Kathleen Hedley, Gary Ironside, Catherine Jefferson, Karen Keenleyside, Joseph Keller, Dave Lacelle, Nathalie Laroche, Liz Lefrançois, Kelly MacDonald, Jiri Marsalek, Elaine McKnight, Tom Tseng, Phil Wong, and Allan Wood.
We would also like to thank Dave Lacelle and Valerie Sexton of the Environmental Economics Branch of Environment Canada for providing expert advice and data from the Municipal Water Use Database surveys on wastewater treatment, municipal water use, and water metering in Canada; and Martha Guy, a consultant for the National Water Research Institute, for her contributions to the database manipulations and expertise in the analysis of contaminant loadings from wastewater treatment plants.
Translation was provided by the Translation Bureau of Public Works and Government Services Canada, and French editing was provided by Les Entreprises Hélène Bruyère. Page layout and graphical design services were provided by Crocodile Communications Inc. and Serge Bédard of the Indicators and Reporting Office.
| • ASP | Amnesic shellfish poisoning |
| • BMP | Best management practice |
| • BOD | Biochemical oxygen demand |
| • CBP | Chlorination by-product |
| • CSO | Combined sewer overflow |
| • DSP | Diarrhetic shellfish poisoning |
| • MUD | Municipal Water Use Database |
| • MWTP | Municipal wastewater treatment plant |
| • PAH | Polycyclic aromatic hydrocarbon |
| • PCB | Polychlorinated biphenyl |
| • PSP | Paralytic shellfish poisoning |
| • SOE | State of the Environment |
| • THM | Trihalomethane |
| • TSS | Total suspended solids |
Environment Canada issues state of the environment (SOE) reports for two key purposes: to provide Canadians with timely and accurate information, in a non-technical manner, about current environmental issues, and to foster the use of science in policy- and decision-making. In examining important environmental issues, the reports attempt to answer four key questions:
By serving these purposes and satisfying the content and presentation guidelines of the federal government’s SOE reporting program, as approved by the five natural resource departments (5NR),1 this report, “The State of Municipal Wastewater Effluents in Canada”, carries the SOE reporting symbol.
The report is intended primarily for policy- and decision-makers at all levels of government and private industry, including municipal councillors, water and wastewater managers, and urban planners, to help them in making informed decisions about municipal water and wastewater management. It also serves to inform concerned Canadians, such as members of non-government organizations and community groups, educators and students, and the media, about the status and trends of one of Canada’s top environmental problems — the release of municipal wastewater effluents. These releases, which include both sanitary sewage and stormwater discharges, are one of the largest sources of human-related pollution, by volume, in Canadian waters.
The State of Municipal Wastewater Effluents in Canada is partly based on an extensive scientific review conducted by Environment Canada to identify the causes, nature, and extent of the impacts of municipal wastewater effluents in Canada (Environment Canada 1997).2 This review was undertaken in association with the Canadian Council of Ministers of the Environment to assess the impact of municipal wastewater effluents on the environment. A version of the science assessment was published in 1997 (Chambers et al. 1997). This scientific review was subsequently updated in an executive summary prepared for senior Environment Canada management in October 1999 (Environment Canada 1999a).
Comprehensive in scope, this report, The State of Municipal Wastewater Effluents in Canada, outlines the sources and the nature of contaminants entering municipal sewer systems, the degree of municipal wastewater treatment across Canada, the wide variety of impacts that municipal wastewater effluents can have on water quality and on plant and animal life, and the implications of these impacts for human health and beneficial water uses, such as shellfish harvesting and recreation. The report concludes by examining how municipal wastewater is managed in Canada and what our society is doing to improve the quality of the effluents to mitigate harmful effects. It also examines important emerging issues, such as the potential endocrine-disrupting hazards associated with toxic substances present in municipal wastewater. It should be noted, however, that the report deals only with wastewater effluents and does not discuss related issues surrounding the handling and disposal of sewage sludge from wastewater treatment plants.
Municipal wastewater effluents represent one of the largest sources of pollution, by volume, in Canadian waters. They are made up of both sanitary sewage and stormwater and can contain grit, debris, suspended solids, disease-causing pathogens, decaying organic wastes, nutrients, and about 200 identified chemicals.
In 1999, of the Canadian population on sewer systems, 97% were served by some level of sewage treatment, while the remaining 3% discharged raw sewage directly to Canadian waters. More untreated sewage was released to coastal waters than to inland waters. Canada has improved its sewage treatment capacity over the past 15 years. The degree of treatment is increasing, with secondary and tertiary treatment provided to 78% of the sewered population in 1999, up from 56% in 1983.
Municipal wastewaters contribute to a number of impacts on Canada’s aquatic environment:
Health problems related to water pollution in general are estimated to cost Canadians $300 million per year. The release of untreated or inadequately treated municipal wastewater effluents may put Canadians at risk from drinking water contaminated with bacteria, protozoans (such as Giardia and Cryptosporidium), and several other toxic substances. Canadians are also put at risk from consuming contaminated fish and shellfish and engaging in recreational activities in contaminated waters.
Economic impacts related to water pollution can be partly attributed to water pollution from sewage. The marine coasts of Canada support a shellfish industry that had a total landed value of over $1 billion in 1997. However, in British Columbia, Quebec, and the Atlantic provinces, the full potential of this industry may not be achieved because of large areas that are closed to harvesting, partly as a result of sewage contamination. Municipal wastewater effluents are also partly responsible for millions of dollars in lost tourism revenue from lost recreational opportunities as a result of beach closures and restrictions on other beneficial water uses.
Excessive water use in Canada increases the need for water and wastewater treatment capacity and reduces wastewater treatment efficiency. Full water pricing by volume used is an effective means of achieving reduced water use. In Canada, metered households used about 288 litres per capita per day in 1999, compared with 433 litres per capita per day for households that paid a flat rate. The percentage of the municipal population with water meters increased from 52.6% to 57.0% between 1991 and 1999.
Many communities have also made improvements over the last 10 years in recognizing and addressing pollution problems resulting from stormwater runoff and combined sewer overflows. In general, the standard of municipal wastewater management that now exists in Canada compares well with that of any other country. However, there are still communities without municipal wastewater treatment, and existing infrastructure is faltering in many parts of the country. Even in areas with a high degree of municipal wastewater treatment, toxic substances, many with unknown ecological consequences, may be released to the environment. As an example, endocrine-disrupting substances can pass through wastewater treatment systems. These substances are known to disrupt or mimic naturally occurring hormones and may have an impact on the growth, reproduction, and development of many species of wildlife.
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