September 18, 1995
Sewage is polluting Ontario’s lakes and rivers. Provincial Auditor Erik Peters concluded in his 1994 annual report that effluents from 24 percent of Ontario’s sewage treatment plants (STPs) fail to meet health and environmental guidelines.1 The offending plants pose a danger to the environment and to the health of Ontario residents. Their effluents poison fish and close beaches to swimmers. Throughout the Great Lakes, STPs whose effluents violate provincial water quality guidelines have rendered hundreds of miles of near-shore areas uninhabitable for aquatic life.2 STPs have been major contributors to the environmental degradation experienced in the 43 Great Lakes sites deemed “Areas of Concern” by the International Joint Commission.3 As populations grow, overburdening many of the STPs that are already working close to their capacity, these problems are likely to worsen.
This report looks at the different types of sewage treatment in Ontario, the rules and guidelines purported to regulate STPs, governments’ failure to enforce these rules, the pollution caused by the noncompliant plants, and the environmental, health and social effects of that pollution. It then recommends a number of changes that should be made to stop sewage pollution of lakes and rivers in the province.
Each day in Ontario, residents and businesses flush 5.7 million cubic metres of sewage down their toilets and drains.4 Many of the different materials that make up sewage pose environmental and health risks. Paints contain toluene, a compound that affects speech, vision, and hearing, as well as phenols, which are poisonous if absorbed or ingested.5 Oven and drain cleaners contain sodium hydroxide, a compound that is also poisonous by ingestion and may irritate the skin.6 Human waste can contain disease-causing agents such as bacteria and viruses. While scientists generally know what risks each individual element in sewage presents, they know less about what new dangers arise when the components are all combined. A hazardous compound may be altered to pose greater health and environmental risks when combined with other compounds. The reaction of two ingredients may produce a new product that poses an even greater threat to the environment than each ingredient held on its own. Clearly, sewage is a dangerous product of human activities and so the handling and treatment of this mixture is a very serious matter.
Approximately half of Ontario’s 830 municipalities have sewage treatment systems. The sewage released into these systems enters a network of pipes that connect to much larger trunk sewers leading to sewage treatment plants. These sewer systems often follow the slope of the land, allowing gravity to transport the wastewater to the treatment facilities. Where the landscape will not accommodate the use of gravity, pumping stations are constructed to raise the sewage to the plants.7
Sewage Treatment Plants in Ontario
When the sewage arrives at the treatment plant it is partially “cleaned” to a particular quality and released into a lake, a river or the ground. The effluent quality depends on the type of treatment applied to the sewage. In Ontario, there are five main sewage treatment types:
Primary Treatment: The wastewater, or influent, entering the STP is screened to remove large solid contaminants such as sticks and rags and then left to sit in sedimentation tanks where sand, gravel and other heavy materials settle out of the water. This treatment reduces particulate matter that does not dissolve in the water; it does not, however, reduce dangerous soluble organic matter. Primary STPs treated 18 percent of Ontario’s waste in 1991.8
Secondary Treatment: The wastewater, which has usually undergone primary treatment, flows into aeration tanks where bacteria consume and break down the dissolved organic matter. Oxygen is pumped into the aeration tank to allow the bacteria to grow and eat. Next, the wastewater enters another sedimentation tank to allow any remaining particles to settle; a metal salt solution is added to remove phosphorus, which would otherwise promote algae growth and cause eutrophication in the receiving waters.9 (Eutrophication refers to the biological changes in a lake or stream caused by the input of excessive amounts of plant nutrients.) Finally, chlorine is added to kill harmful micro-organisms before the effluent is released into receiving waters. In 1991, secondary STPs treated 72 percent of the province’s sewage.10
Tertiary Treatment: This process uses sand filtration or additional lagoons to further treat the wastewater after secondary treatment. A better quality effluent with lower levels of contaminants is the product of this treatment. Tertiary STPs treated 4.3 percent of Ontario’s sewage in 1991.11
Lagoons: The wastewater is purified by biological activity (bacteria) at naturally occurring rates in shallow basins. This treatment method requires the longest time of all the treatment types because the air required by the bacteria is supplied by oxygen transfer between the atmosphere and the liquid sewage surface.12 Once treated, the effluent is either released into rivers and lakes or allowed to infiltrate into the ground. Lagoons are primarily used for small communities because of their relative low construction and operating costs. In 1991, 5.7 percent of Ontario’s sewage was treated using lagoon treatment.13
Communal Septic Systems: Used only for small communities, this system consists of a single storage settling tank which holds the sewage while anaerobic bacteria (bacteria that do not require oxygen to live) decompose the solids that settle. The effluent is released slowly into the earth below the settling tank. Such systems handled 0.01 percent of Ontario’s sewage in 1991.14
Some Ontario communities and businesses are beginning to experiment with alternative sewage treatment methods on a small scale. A marsh providing secondary and tertiary treatment is being tested in Niagara-on-the-Lake. In Toronto, the Body Shop processes its waste using solar aquatic technology. Infiltration basins which hold effluent and allow it to penetrate into the ground have been proposed in Barrie, Ontario.15
Organized from the highest degree of treatment to the lowest degree of treatment, the above methods appear in the following order: tertiary, secondary, lagoons, primary and communal septic.16 The higher the degree of treatment, the more purified the effluent discharged by the STP into the receiving waters.
The effluent from a primary treatment plant poses a much greater environmental and health risk than the effluent from a secondary or tertiary treatment plant. Each day, over one million cubic metres of sewage receive only primary treatment before being released into Ontario waters.
In Ontario, there are 423 sewage treatment plants. The provincial Crown operates 244 STPs and municipalities operate 179 STPs. The Ontario Clean Water Agency, a provincial Crown corporation created in 1993, operates 160 of the provincial STPs, while the Ministry of Environment and Energy (MOEE) operates the remainder. In general, the larger STPs, for example, the Main Treatment Plant in Toronto, are operated by a municipality and the smaller STPs, such as that in Orangeville, are operated by the province. Table 1 contains a breakdown of Ontario STPs by both treatment type and operating authority.
Table 1: Sewage Treatment Plants Operated by the Province or Municipalities (1991)17
|Treatment Type||# Operated by Province||# Operated by Municipalities||Total|
|Total||244 (58%)||179 (42%)||423|
Sewage Treatment Plant Effluent
Treated wastewater that STPs release into lakes and rivers is called effluent. The MOEE measures effluent quality using three parameters: Biological Oxygen Demand, Suspended Solids, and Total Phosphorus. Biological Oxygen Demand (BOD5) is the amount of oxygen used by micro-organisms as they decompose organic matter in the effluent sample for five days. High BOD5 in effluent means a large quantity of oxygen was needed to break down the organic matter. This identifies a large amount of organic matter in the effluent and indicates inadequate treatment. Suspended Solids (SS) measures the amount of undissolved solids in an effluent sample. Excess SS in effluent can fatally clog fish’s gills and can be aesthetically displeasing. Trace metals and organics, harmful to human health and the environment, can adhere to suspended solids and enter the waters of Ontario in the effluent released by the STPs. Total Phosphorus (TP) refers to the amount of phosphorus in a sample. Excess TP stimulates algae and weed growth which causes large fluctuations in the dissolved oxygen in the receiving waters, affecting aquatic life.
The Industrial Lab in Toronto tests the effluent from the four main STPs in the city. In addition to measuring BOD5, SS, and TP, the lab also tests the levels of 12 heavy metals and 120 different organic compounds; however, most of these substances do not have ministry standards because not enough is known about their effects to set limits.18
In Ontario, three MOEE policies specify guidelines for effluent quality. MOEE Policy 08-01–“Levels of Treatment for Municipal and Private Sewage Treatment Works Discharging to Surface Waters”—prescribes levels of treatment based on the effluent quality that each treatment type is capable of achieving. Therefore, the level of treatment required at a secondary STP is higher than that required from a primary STP. MOEE Policy 08-04–“Policy to Govern the Provision, Operation and Assessment of Phosphorus Removal Facilities at Municipal, Institutional and Private Sewage Treatment Works”—describes the requirements for the removal of phosphorus from effluent. MOEE Policy 08-06–“Policy to Govern the Sampling and Analysis Requirement for Municipal and Private Sewage Treatment Works (Liquid Waste Streams Only)”—outlines the MOEE sampling and analysis requirements for the purpose of assessing STP performance and compliance with effluent requirements.
Table 2 presents the MOEE Policy Guidelines based on Policy 08-01 and the 1983 Canada-U.S. Agreement on the Great Lakes Water Quality.
The MOEE requires the operator of each STP to monitor its performance and to report the results to the MOEE. The operator measures the BOD5, SS, and TP in both the influent and the effluent to determine the amount of treatment achieved. The results are compared to the general effluent guidelines and to specific limits established for each STP; the amount of treatment indicated by the three parameters must comply with either MOEE Policy 08-01 or, if more stringent, the limits stated in the STP’s Certificate of Approval (C of A).
The C of A is a legal document issued by the MOEE approving the construction and operation of an STP. Stipulated in the C of A are the effluent concentration limits established by an environmental assessment prior to construction of the STP. The limits, based on the amount of effluent that the receiving water is capable of handling without adverse effects, are usually more stringent than the guidelines in MOEE Policy 08-01.20
If an STP in Ontario does not comply with the effluent guidelines, enforcement action under the Ontario Water Resources Act or the Environmental Protection Act can result.
Table 2: MOEE Policy Effluent Guidelines Based on Policy 08-01 and the 1983 Canada-U.S. Agreement on the Great Lakes Water Quality 19
BOD5 SS TP
|Type of Treatment||Annual
|without TP||removal 30%||removal 50%||removal NA|
|with TP||removal 50%||removal 70%||removal 1 mg/L*|
|without TP removal||25 mg/L||25 mg/L||NA|
|with TP removal||25 mg/L||25 mg/L||1 mg/L|
|without TP removal||30 mg/L||40 mg/L||NA|
|continuous TP removal||30 mg/L||40 mg/L||1 mg/L|
|batch TP removal||25 mg/L||25 mg/L||1 mg/L|
NA = not applicable
* in one litre of effluent, not more than 1 milligram of phosphorus is allowed
Laws Governing STP Effluent Discharge
In addition to the MOEE guidelines discussed above, a number of federal, provincial, and municipal laws and policies govern the discharge of STP effluent into the environment. As governments lack the political will to enforce these laws, most are more effective in theory than in practice.
Common Law: Common law property rights, when not overridden by government laws and regulations, can function to protect the environment. Under the common law, placing pollutants on someone’s property, either directly or via water or other means, constitutes a trespass. A court case from the early 1900s illustrates the use of trespass law to protect the environment.21 A New York court issued an injunction against a town that emptied its sewers into a creek that flowed through a farmer’s land, polluting the creek’s bed and banks. With the sewage the town had trespassed, violating the farmer’s rights.
Nuisance law, another branch of the common law, can also be used to protect water quality.22 The foundation of nuisance law is that someone can use and enjoy his or her own property but not in a way that compromises others’ enjoyment of their property. In 1922, the City of Woodstock constructed an STP to handle a population of 9,000.23 As the population increased, the sewage load surpassed the design capacity of the STP, resulting in the discharge of raw and improperly treated sewage into the Thames River. A dairy farmer downriver found his cows developing dysentery; milk production decreased, and calves were aborted. In 1955, the dairy farmer went to court and obtained an injunction and damages. Woodstock was found guilty of creating a nuisance by polluting the river.
From the simple rule that someone may not harm another’s property, or interfere with his or her enjoyment of it, a separate branch of the common law called riparian law developed. Riparian law is used to protect lakes and rivers from changes in water quality and flow. Preventing even subtle changes, such as the hardening or warming of water, traditional riparian law surpasses the zero discharge regulations now sought after by many environmentalists. Riparians–waterfront property owners–can sue water polluters and obtain injunctions against them. Under the common law, riparians’ rights exist even if they do not use the water or if the pollution does not interfere with their activities. If they can demonstrate that a proposed activity will violate their riparian rights, riparians may act even before a river or lake is polluted.
The Village of Richmond Hill, in 1952, constructed a sewage disposal plant that discharged effluent in the Don River.24 The plant became too small for the population, polluting the river and its banks. A land owner downriver filed a lawsuit claiming that Richmond Hill had violated her riparian rights. The judge in the case stated that a riparian has the right to the natural flow of a river and issued an injunction against the pollution.
In both the Woodstock and Richmond Hill cases, the provincial government overrode the court decisions. It expressly authorized the STPs to continue operating and prohibited victims from seeking court injunctions in the future. All STPs in the province were deemed to be operating under “statutory authority,” immunizing them from common law court challenges. The statutory authority provision is still in effect; until it is appealed, victims will remain powerless to use property rights to prevent sewage pollution.
Federal Fisheries Act: This act is the Federal Government’s major tool for the protection of water quality and fisheries. Section 36(3) prohibits persons from depositing deleterious substances into water frequented by fish. A British Columbia court ruled in 1979 that the deposit of even minuscule amounts of a deleterious substance could violate the act.25
In Ontario, the provisions of the act are enforced by the Ministry of Natural Resources (MNR) in consultation with the Canadian Department of Fisheries and Oceans. The maximum fines on indictment are up to $1,000,000 on the first offence and $1,000,000 and up to three years’ imprisonment for subsequent offences.
While its strict provisions and tough penalties could make the Fisheries Act a powerful weapon against STPs, governments have been reluctant to enforce it. In fact, no Ontario STPs have yet been prosecuted under the act.
Ontario Water Resources Act (OWRA): The OWRA is the provincial government’s main legislative tool for the control of water pollution and the management of water resources. The act is the primary statute governing the construction, operation, and maintenance of sewage treatment and disposal facilities in Ontario.23 It is under the OWRA that a C of A must be acquired for the discharge of sewage or treated water into surface waters. The act also authorizes the MOEE to analyse surface waters to determine the extent and cause of water contamination and empowers the ministry to regulate sewage treatment systems. 25
Under Section 16 of the OWRA, it is an offence to discharge a substance that may impair water quality. Maximum fines for violators of the act are $10,000 for the first offence and $25,000 for subsequent offences. For corporate prosecutions, the first offence fine is $50,000 and each subsequent fine is $100,000.
Under the OWRA, the MOEE has developed a policy tool, entitled “Water Management: Goals, Policies, Objectives, and Implementation Procedures of the Ministry of the Environment” (often referred to as the “Blue Book” because of the colour of its cover), to give direction on how to manage the quality of surface water and ground water. It provides Provincial Water Quality Objectives (PWQOs) which are the recommended concentrations of contaminants for the water quality desired by the MOEE. The PWQOs are not legal standards but instead often serve as a starting point for the limits in STPs’ C of As.
Municipal-Industrial Strategy for Abatement (MISA): In 1986, the provincial government introduced MISA, in part to address the weaknesses of the Blue Book.26 The stated goal of the strategy is the “virtual elimination of persistent toxic pollution from [Ontario] waterways.”
The MISA program is divided into nine industrial sectors and one municipal sector. As of July 1995, the industrial regulations had all been promulgated; however, the municipal sewage use and effluent regulations were only in the consultation stages.27 Included in the MISA Municipal Program will be a sewer use program and an STP program. In the sewer use program, municipalities will be required to adopt a sewer use bylaw containing effluent limits and control measures. There are two components planned for the STP program. The first component will be STP effluent limits regulation for approximately five conventional pollutants and the second will be the upgrading of the primary STPs in Ontario to secondary treatment plants. A 20-year time allowance for the municipalities to comply is proposed because of the large financial investment required for the upgrading.
Ontario Environmental Protection Act (EPA): This act contains a general prohibition against the discharge into the natural environment of contaminants that may adversely affect plants, animal life and human health.28 While the OWRA covers pollution of surface waters, the EPA deals with subsurface pollution.
Environment Assessment Act (EAA): The EAA provides a process through which significant impacts on the environment may be prevented before a project is implemented. While many STPs are subject only to a Class EA, some are “bumped up” to a full EA and required to undergo a hearing by an environment assessment panel. The panel may deny approval or impose terms and conditions on the construction and/or expansion of an STP.
Municipal Act: The Municipal Act describes the powers given to municipalities to regulate and control a wide variety of activities. Under the act, municipal councils are permitted to construct and operate municipal sewer systems and to pass bylaws to control the quality of wastewater released into sewer systems by industry. For example, in 1989, the municipality of Metropolitan Toronto adopted Bylaw No. 153-89 “To regulate the discharge of sewage and land drainage in the Metropolitan area.” This bylaw includes sections covering discharges to sanitary, combined, and storm sewers, compliance program information, sampling and analysis of wastewater, and offences.
The province’s model sewer-use bylaw suggests the maximum concentration limits for conventional pollutants such as BOD, SS, TP, pH, nitrogen, temperature, and 24 heavy metals. Adoption of the bylaw by municipalities is voluntary. A municipality that does adopt the bylaw can set more stringent and comprehensive limits than those imposed by the province. One survey of 88 municipalities revealed that less than half of the municipalities have adopted some form of a model sewer-use bylaw.29 Furthermore, the bylaws that are in effect are often inadequate, failing to address many of the organic and inorganic compounds that end up in Ontario’s waters.
In Ontario, the MOEE documents environmental degradation from STPs and plant operational problems in Occurrences Reports. If abatement measures are required, the operating authority (either the MOEE or the municipality) of the STP in question is given a period of time in which to take actions to remedy the problems. The Occurrences Report may be referred to the Investigations and Enforcement Branch (IEB) if it is suspected that an STP has violated legislation–usually the Environmental Protection Act or the Ontario Water Resources Act– and does not comply with the abatement measures. The operating authority may then be prosecuted by the Ministry’s Legal Services Branch.
Although effluent monitoring has exposed 91 STPs that are causing environmental pollution by exceeding effluent limits (see below), there have been few prosecutions. In 1990, the Regional Municipality of Sudbury was found guilty of violating its C of A for illegal discharge of lagoon contents.30 In 1991, IEB investigated two suspected infractions; however, no charges were laid. There have been no prosecutions since.31
A number of factors contribute to governments’ failure to enforce water quality laws and regulations. The province experiences conflicts of interest that prevent it from effectively regulating the STPs that it operates. Provincial regulators are sensitive to the fact that much pollution results from technical problems that require costly equipment upgrades; they thus overlook them, postpone expensive repairs by initiating inexpensive studies, or give the STPs generous time periods in which to remedy the problems. Provincial officials also refrain from prosecuting municipal violators for fear of appearing hypocritical for targeting plants not operated by the Crown. And municipalities’ tight financial situations, their reluctance to fine community employers, and a shortage of trained personnel contribute to their failure to prosecute STP operators.32
Ontario Sewage Treatment Plants’ Compliance with Effluent Guidelines
In 1991 the MOEE analysed the effluent from 387 STPs using the three above noted parameters: BOD5, SS, and TP.33 It assessed the effluent BOD5 and SS for each STP against the limits set in the C of A or, if an STP had no C of A in effect, the guidelines in MOEE Policy 08-01. The TP for each STP was assessed against guidelines in the 1983 Canada-U.S. Agreement on the Great Lakes Water Quality.
A total of 91 STPs in the study did not meet the effluent limits or guidelines. Out of 325 STPs without C of As, 80 did not comply with the less stringent MOEE policy guidelines for at least one of the three parameters. Eleven of 62 STPs that had a C of A did not meet the stated effluent limits. It is possible that eight plants that did not provide data (and were therefore not studied) also performed inadequately and could be added to the number of non-complying STPs. Furthermore, as pollution resulting from bypasses was not considered in the effluent analysis, some “complying” plants were nonetheless responsible for severe water pollution.
The MOEE’s data indicates a dramatic five-year decline in STP performance. The number of Ontario STPs exceeding MOEE BOD guidelines increased from 16 to 22 between 1986 and 1991. Similarly, the number of plants that exceeded MOEE SS guidelines increased from 47 in 1986 to 60 in 1991.34
The worst performing STP in 1991 was the Belle Vallee Lagoon in north eastern Ontario. There the average BOD was four times greater than the MOEE effluent limit of 30 mg/L and the SS was almost 10 times greater than the limit of 40 mg/L.35 Table 3 lists the five worst and five best performing Ontario STPs in 1991.
Table 3: Five Worst and Best Performing Ontario STPs (1991)36
Effluent Limits (mg/L) Average Effluent Quality (mg/L)
|Five Worst Performers||BOD||SS||TP||BOD||SS||TP|
|Belle Vallee Lagoon||30.0||40.0||NA||118.0||380.0||38.2|
|Five Best Performers||BOD||SS||TP||BOD||SS||TP|
|New Hamburg Lagoon||30.0||40.0||NA||2.3||1.5||0.38|
|Port Carling WPCP||25.0||25.0||1.0||1.3||1.3||0.14|
|Victoria Harbour WPCP||25.0||25.0||1.0||1.6||1.2||0.13|
Note: WPCP is an abbreviation for water purification control plant
In the 1991 report on STP discharge, the effluent quality for each of the 387 STPs was assessed using the annual averages for BOD, SS, and TS. The MOEE, when commenting on the publication of 1989 discharges from Ontario STPs, stated that the number of STPs not in compliance with the effluent guidelines and limits would greatly increase if the limits and guidelines were applied to the monthly average concentrations rather than the annual averages.37 It is assumed that the same would apply to the 1991 effluent results described above. Therefore, it is likely that well over 91 STPs did not comply with effluent guidelines and limits in 1991.
Factors Affecting the Performance of Sewage Treatment Plants in Ontario
In 1992, the MOEE published a report assessing the factors that contribute to the poor performance at Ontario STPs. Twelve secondary STPs, each with a history of performance problems, were evaluated to identify the causes.38 It was found that operational, administrative and design factors combined to cause poor performance at specific plants.
Operators demonstrated a general lack of understanding of the fundamentals of sewage treatment processes and poor application of these concepts to the process control. Some STPs lacked process monitoring and testing on which to base control decisions. Excessive hydraulic loading (too much wastewater for the capacity of the STP) impaired the performance of many of the STPs. Eight of the 12 STPs were operating at more than 90 percent of the designed hydraulic capacity. Inadequate instrumentation and sludge disposal were also identified as problems.
The 1992 report estimated that the cost of modifications to operating strategies and minor physical changes needed to improve the performance of the 12 STPs would be $4.7 million. Extended over the province, it was estimated that it would cost $100 million to improve the operation of municipal secondary STPs to comply with monthly BOD5 and SS effluent guidelines. That cost did not include the costs of improved training of staff, increased enforcement of regulations, or changes to policy factors limiting optimal plant performance. The much needed upgrading of primary STPs to secondary treatment facilities presents yet another huge financial investment.
In emergency situations, the MOEE allows STPs to “bypass” raw sewage directly into Ontario receiving waters. The MOEE lists three situations that may justify bypasses.39 First, a significant increase in the amount of wastewater flowing into an STP during a storm or spring thaw may require a bypass to prevent basements from flooding when the sewers back up. Second, equipment breakdown and other operational problems in the STPs may require bypassing to prevent the damage of equipment at treatment works or pumping facilities. Third, when population and/or industrial growth exceeds the design capacity of the STP, bypassing may be necessary to prevent a washout of solids in the treatment works during storm events. In other words, when a storm occurs, a bypass allows for the quick removal of solids and speedy discharge of the wastewater to handle the large inflow into the STP and prevent the release of solid waste into the receiving waters.
Of the 204 STPs that reported bypass information to the MOEE in 1991, 75 had bypass occurrences.40 As 52 STPs did not provide bypass data to the MOEE, it is not known how much they bypassed into Ontario waters. (The 169 lagoons in Ontario did not have to report bypass information because they were not designed with bypass provisions.) The total annual volume of reported primary bypass in 1991 was 2.2 million cubic metres; reported secondary bypass accounted for 9.6 million cubic metres. While this accounts for 0.11 percent and 0.46 percent of the total volume of effluent treated in 1991 respectively, both figures represent a very large quantity of toxics and contaminants entering the environment. In addition, these figures would likely be even greater if contributions from the 52 STPs that provided no bypass information were added.
Table 4: Toxics Found in STP Effluents and Their Effects on the Environment
|Heavy Metals||Environmental Effects|
|Cadmium||neurotoxin (attacks nerve cells); teratogen (causes birth defects)|
|Chromium||carcinogen (causes cancer)|
|Copper||causes nausea, vomiting, coma, jaundice, diarrhea|
|Nickel||carcinogen; affects immune and respiratory systems|
|Zinc||causes nausea, vomiting, abdominal pain, diarrhea|
|Agricultural Chemicals (Pesticides)|
|2,4-D||central nervous system depressant; poisonous by ingestion|
|Lindane||poisonous by ingestion or absorption through skin; neurotoxin|
|DDT / D / E||neurotoxin|
|PCBs||cause skin disorders; carcinogens in lab animals|
|Dioxins and Furans||neurotoxins; carcinogens; suppress immune system in animals; cause skin disorders, liver damage, depression and internal bleeding|
|Chloroform||suppresses immune system; carcinogen in lab animals|
|Xylenes||central nervous system depressant; suppresses immune system|
|Tetrachlorethylene||central nervous system depressant; poisonous by ingestion or absorption through skin; carcinogen in lab animals|
|Trichloroethylene||central nervous system depressant; poisonous by ingestion or absorption through skin, irritates skin; carcinogen in lab animals|
|Cresol, phenol||poisonous by ingestion or absorption through skin|
Toxic Materials in Sewage Treatment Plant Effluent
In addition to the organic matter frequently found in treated effluent, STPs regularly discharge inorganic toxic materials into lakes and rivers. While basic sewage treatment can adequately remove organic materials using primary and secondary processes, toxics are not removed. Many toxics in sewage travel through the STP and are discharged into waters or remain in the sewage sludge to be burned or spread on agricultural land.42
Toxics–substances that poison humans in low doses and kill 50 percent of test animals at stated concentrations43–include heavy metals such as mercury and lead, pesticides such as DDT, and industrial chemicals such as PCBs and dioxins. Table 4 lists the “top 20” toxics found in STP effluents in the Great Lakes and St. Lawrence river in Ontario and the U.S. In addition, the table includes the environmental effects of each toxic to illustrate the potential danger that STP effluents pose to human life and the environment. It should be noted that the presence of one contaminant may increase or decrease the toxicity of another contaminant.44
Once discharged into lakes and rivers, the toxics and other contaminants in STP effluent may bioaccumulate and/or biomagnify. Bioaccumulation refers to the retention of chemicals that are nonbiodegradable or slowly biodegradable in the body of humans and other organisms.45 This accumulation of chemicals becomes dangerous as levels increase and approach concentrations that are toxic and lethal. The concentration of chemicals increases in successively higher trophic levels of the food chain, a process referred to as biomagnification.46 Organisms high on the food chain, such as eagles and humans, experience increased concentrations of toxics and other contaminants when they ingest contaminated plants and fish.47
Effects of Sewage Treatment Plant Effluent on Aquatic Organisms
As noted above, STP effluents may harm fish and other aquatic life. High SS concentrations can fatally clog fish’s gills and a high BOD deprives aquatic life of essential oxygen. A number of studies have examined the effects of STP effluents on aquatic life. The majority of these tests have been executed in the laboratory to calculate the toxicity of effluents. Biological responses showing an impairment of normal functioning of an organism as a result of critical exposure to the effluent have illustrated toxicity.48 Tests determine if the effluent as a whole–rather than each individual ingredient within the effluent–affects the test organisms. The responses usually measured have included lethality, growth rate, reproduction success, and physiological function.49
Acute toxicity tests and chronic toxicity tests are often used to illustrate the effect of effluent on a receiving water ecosystem and to measure the combined toxicity of individual effluent contaminants.50 Chronic tests measure long-term effects of exposure that contribute to ecosystem impairment by affecting organisms’ growth and reproduction rates and many other important functions. Acute lethality is measured with LC50, which refers to the concentration of a contaminant that kills 50 percent of the exposed organisms.
A 1990 government review of the impact of STP effluents on aquatic environments concluded that the limited evidence showed primary effluents to be generally acutely lethal.51 It noted, however, that more studies were necessary for sufficient results. Secondary and lagoon treatments were found to produce varying effluent quality illustrating that conditions at each individual STP, rather than the treatment type, have a direct impact on lethality. The 1990 review also found that chronic toxicity was inadequately studied.
A 1992 study assessed the lethal and sublethal effluent toxicity from 10 Ontario STPs.52 The STPs tested ranged in scale from the Bracebridge STP in the Muskoka region to the North Toronto STP in Metropolitan Toronto. Fifty six percent of the grab and composite samples were acutely lethal to rainbow trout exposed in the laboratory. Only Walkerton STP effluent was consistently non-lethal to trout in the summer and winter. Twenty seven percent of the samples were lethal to the test fish species Cladocera. Finally, 69 percent of the samples caused reduced growth of fathead minnow larvae and 56 percent of the samples impaired reproduction in another test fish species.53
Table 5: Toxicity Studies in Receiving Waters of Ontario STPs
|Greenway||Thames River||1979||28||20% mortality after 18 hrs.|
|Stratford||Avon River||1982||17.3||98% mortality after 6 hrs.
100% mortality after 20 hrs.
|475||2% mortality after 48 hrs.
66% mortality after 120 hrs.
|Tillsonburg||Big Otter River||1982||4.5||50% mortality after 5.3 hrs.|
|53||50% mortality after 6.4 hrs.|
|Walkerton||Saugeen River||1977||17||56% mortality after 48 hrs.|
|183||53% mortality after 48 hrs.|
Four effluent toxicity studies have been conducted in Ontario in which cages of Rainbow Trout and Rosey Face Shiners were placed in receiving waters at varying distances downstream from STPs.54 Table 5 shows the results of these toxicity studies. After just six hours of exposure 17 metres downstream from the Stratford STP, almost all of the fish died. It took slightly over five hours for 50 percent of the fish to die four and a half metres downstream from the Tillsonburg STP. These findings illustrate the unacceptably high toxicity of effluent released into Ontario rivers. Even as far downstream as half a kilometre from the Stratford STP, it took just five days for two thirds of the fish to die, illustrating how river polluters pass their problems down river to unsuspecting communities.
Eutrophication and Sewage Treatment Plant Effluents
The nutrients in STP effluents (nitrates and phosphates) contribute to the eutrophication of lakes and rivers. In warm weather, the nutrient loading produces large growths of algae, cyanobacteria, water hyacinths, and duckweed which, when they die, fall to bottom and are decomposed by aerobic bacteria. The bacteria use up dissolved oxygen in the water; this depletion of oxygen then kills fish and other oxygen-consuming aquatic animals. If nutrient loading continues, the dissolved oxygen is further depleted, anaerobic bacteria take over, the bottom water becomes devoid of animals and smelly decomposition products such as hydrogen sulphide and methane are produced.
Ontario beaches are closed–or “posted”–when fecal coliform densities exceed 100 colonies per 100 mL of water. Fecal coliforms are bacteria in the feces of humans and animals; their presence in lakes and rivers indicates the degree of fecal contamination. Bacteria from fecal matter cause disease, skin, eye, ear, nose and throat infections as well as stomach disorders.
Poor quality effluent, sewage treatment plant bypasses, combined sewer overflows and faulty septic systems lead to beach postings. Combined sewers transport both sewage and stormwater to the STP. During heavy rainstorms, combined sewers are designed to release untreated excess flow–flow that cannot be handled by the STP–directly into lakes and rivers. Therefore, in the event of a heavy rainstorm, partially treated and untreated effluent from bypasses and a mixture of untreated domestic sewage, industrial wastewater, and stormwater are dumped into lakes and rivers, leading to high coliform bacteria counts and beach closings.
From 1986 to 1994, health authorities posted beaches on an average of 891 times each year in the Toronto area (including Etobicoke and Scarborough).55 Twenty eight different beaches in the Toronto area were posted during this period.56 Western Toronto beaches were posted 55 percent of the swimming season in 1985; that figure increased to 89 percent in 1989.57 Several Toronto beaches are permanently posted with warnings to swimmers about the risks of swimming within 48 hours after a heavy rainstorm. Six beaches in Etobicoke have each been posted for an entire summer (91 days) at least once since 1992.58 The situation shows no signs of improving. In the words of one Department of Health representative, “the money it would take to reopen the western beaches is prohibitive.”59
Toronto’s eastern beaches are cleaner than their western counterparts. Beach postings decreased from 1985 to 1989 and several beaches had no postings in the summer of 1989.60 The improved water quality results from a $4.4 million holding tank that holds 2250 cubic metres of combined sewer overflow in the event of a storm. Effluent from four storm sewers and one combined sewer flows into the tank and is stored until an STP can treat it.
Conclusions and Recommendations
As the volume of sewage increases and as older systems deteriorate, Ontario’s already overburdened sewage treatment system will be further stressed.61 To prevent more deterioration of our lakes and rivers, and to clean up the damage that has already been done, the federal, provincial and municipal governments should take the following actions:
Restore property rights: The restoration of common law rights to clean water would ensure that those most affected by polluting STPs could obtain court injunctions forcing the plants to clean up their effluents. In restoring property rights, governments should repeal laws and regulations that allow trespasses, nuisances or violations of riparian rights. As a first step, the provincial government should repeal Section 59 of the Ontario Water Resources Act, which shields polluting STPs from lawsuits by stating that plants constructed, operated, maintained, approved or ordered under the OWRA or the EPA operate under “statutory authority.”
Enforce existing laws: If the provincial government is unwilling to enforce its own water quality standards, the federal government, municipalities, and ordinary citizens should use the power of the Federal Fisheries Act to prosecute STPs polluting Ontario waters.
Raise water prices: Increasing water prices would, by reducing water use, reduce wastewater flows. Higher prices would thereby reduce the strain on STPs, many of which now operate at over 90 percent of their designed wastewater flow capacity. Reductions in wastewater flows would increase STPs’ efficiency and improve the quality of their effluents.
Meter wastewater quality: Only when it costs more to dispose of contaminated water than it does to dispose of relatively clean water will households and industries have disincentives to flush pollutants down their drains. While industry contributes the majority of toxics to the sewer systems, 15 percent of pollutants that are regulated come from households.62 Households are the largest contributor of volatile organics, such as toluene and xylene, into the sewer systems.
Privatize sewage treatment plants: Governments regulate others more effectively than they regulate themselves. The conflicts of interest that prevent provincial and municipal governments from responsibly regulating the STPs that they own and operate could be eliminated by selling STPs to private sector bidders. Governments could then get tough with STP operators, requiring them to meet long-ignored standards. Privatization of the water industry in Britain has resulted in upgraded sewers, less near shore pollution, and fewer beach postings.63 Only when governments here in Canada lose their economic incentives to tolerate pollution will we achieve similar progress.
Appendix A:Ontario STPs That Did Not Comply with MOEE Policy Effluent Guidelines in 199164
|Plant Name||Operating Authority|
|Brigden P.V. Lagoon||Province|
|Grand Bend Lagoon*||Province|
|Ingersoll New WPCP*||Province|
|Kilworth Heights WPCP||Province|
|Merlin P.V. Lagoon||Province|
|Oil City Lagoon||Province|
|Oil Springs Lagoon*||Province|
|Owen Sound WPCP||Province|
|Point Edward WPCP*||Province|
|Port Lambton Lagoon||Province|
|Port Stanley Lagoon||Province|
|Stoney Point P.V. Lagoon||Province|
|West Central Ontario|
|Baker Road WPCP||Municipality|
|Crystal Beach WPCP*||Municipality|
|Mount Forest WPCP||Municipality|
|Port Dover WPCP||Province|
|St. Jacobs P.V. WPCP||Province|
|Woodward Ave. WPCP||Province|
|Clarkson WPCP South||Province|
|Cobourg WPCP No. 1*||Municipality|
|Corbett Creek WPCP||Municipality|
|Duffin Creek WPCP*||Municipality|
|Fox St. STP||Municipality|
|Main WPCP (Toronto)||Municipality|
|Oakville South West||Municipality|
|Port Hope WPCP||Municipality|
|Carleton Place WPCP*||Province|
|Chalk River WPCP||Province|
|Deep River WPCP||Municipality|
|Robert Pichord Env. Centre*||Municipality|
|Smiths Falls WPCP*||Municipality|
|Belle Vallee Lagoon||Municipality|
|Iroquois Falls WPCP||Province|
|New Liskeard Lagoon*||Municipality|
|Virginiatown & Kearns*||Municipality|
|Fort Frances WPCP||Province|
|Sioux Lookout WPCP||Municipality|
|Thunder Bay WPCP*||Municipality|
* STPs that did not comply with MOEE policy effluent guidelines from 1987 through 1991
Note: The following seven municipal STPs provided insufficient data for assessment: Amherstberg WPCP, Kingsville Lagoon, Tilbury Lagoon, Smithville Lagoon, Washago Lagoon, Bath WPCP, Embrun Lagoon.
Primary Treatment Plants in Ontario (Partial Listing) 65
West Central Ontario
Nanticoke (Port Dover)
Robert O. Pickard Environment Centre
Sault Ste. Marie
1. Globe and Mail, “Ontario water quality questioned.”
2. World Wildlife Fund, Toxics from Sewage Treatment Plants, 2.
3. Ibid., 3.
4. MOEE, Report on the 1991 Discharges from Municipal Sewage Treatment Plants, 37.
5. World Wildlife Fund, Toxics from Sewage Treatment Plants, 10.
6. Ibid., 10.
7. The Municipality of Metropolitan Toronto, The Sewage Treatment Process.
8. MOEE, Report on the 1991 Discharges from Municipal Sewage Treatment Plants, 35.
9. The Municipality of Metropolitan Toronto, The Sewage Treatment Process.
10. MOEE, Report on the 1991 Discharges from Municipal Sewage Treatment Plants, 35.
11. Ibid., 35.
12. Beak Consultants, Review of Aquatic Toxicity and Environmental Impact of Ontario Sewage Treatment Plant Effluents, 5.
13. MOEE, Report on the 1991 Discharges from Municipal Sewage Treatment Plants, 35.
14. Ibid., 35.
15. Miller, in Living in the Environment: Principles, Connections, and Solutions, reports that over 150 cities and towns in the U.S. now use natural and artificial wetlands for treating sewage. He describes a case study in which Arcata, a coastal town of 15,000 in California, constructed 63 hectares of wetlands on land that previously functioned as a dump. The wetlands cost $3 million less than the estimated cost of a conventional treatment plant and function as an inexpensive, natural waste treatment plant. Some water from the marshes is pumped into the city’s salmon hatchery, eventually making the marsh treatment plant into a profitable project. The treatment centre is a city park and the marshes and lagoons are an Audubon Society bird sanctuary, providing habitat for thousands of seabirds, otters, and marine animals.
Miller also describes a greenhouse lagoon, an alternative to a wetland if space is limited. This system functions in much the same way as an outdoor wetland, however, it is contained within a greenhouse. When the greenhouse lagoon system is working properly, it produces water fit for drinking. While not ideal for the large sewage flow of large cities, both the wetland and greenhouse lagoon are practical natural treatment alternatives for smaller towns, the edges of urban areas, and rural areas.
16. MOEE, Report on the 1991 Discharges from Municipal Sewage Treatment Plants, 35.
17. Ibid., 30. Interest in privatizing wastewater systems is growing in Ontario. In 1995, Hamilton-Wentworth contracted operations with a private company to operate its sewage plant. The region will retain ownership of the system and receive a portion of the savings realized from the private management (Globe and Mail, “Philip to run Hamilton water system”). In May 1995, the Region of Halton put out a request for proposals for the private operation of a yet-to-be-built water and sewage treatment plant (Now, “Should private companies own the water coming out of your taps?”). No municipalities, however, have fully privatized their systems, transferring ownership–rather than merely operations–to a private firm.
18. July 1995 telephone conversation with Tibor Haasz, of the Toronto Industrial Lab, who tests the effluent from Toronto’s four main STPs (Main STP, Humber STP, North Toronto STP, and Highland Creek STP).
19. MOEE, Report on the 1991 Discharges from Municipal Sewage Treatment Plants, 5. TP removal requirements reflect the dilution capabilities of the receiving waters.
20. Ibid., 3.
21. Brubaker, Property Rights in the Defence of Nature, 32.
22. Ibid., 43.
23. Ibid., 83-4.
24. Ibid., 84-6.
25. Cassidy, Outdated Federal Fisheries Act Fails Sustainable Development.
26. Estrin and Swaigen, Environment on Trial: A Guide to Ontario Law and Policy, 545.
27. Thompson and Kuilman, “MISA Program Update.”
28. Estrin and Swaigen, Environment on Trial: A Guide to Ontario Law and Policy, 532.
29. World Wildlife Fund, Toxics from Sewage Treatment Plants, 8.
30. MOEE, Report on the 1991 Discharges from Municipal Sewage Treatment Plants, 32.
31. John MacLatchy (Environment Protection, Environment Canada), in a 1995 telephone conversation, stated that under Section 36(3) there have been no prosecutions of STPs in Ontario. MacLatchy is the editor of the 1992 Fisheries Pollution Reports. Peter Levedhe (Environment Protection, Toronto District office), in a 1995 telephone conversation, knew of no prosecutions under the OWRA or the EPA.
32. World Wildlife Fund, Toxics from Sewage Treatment Plants, 8.
33. MOEE, Report on the 1991 Discharges from Municipal Sewage Treatment Plants. Thirty six STPs were not included in the 1991 study because 27 plants did not discharge in surface waters and, therefore, were not required to report effluent data; one STP was operated for only part of the year; eight STPs did not provide sufficient data.
34. Ibid., 28.
35. Ibid., 15.
36. Ibid., 15.
37. MOEE, Assessment of Factors Affecting the Performance of Ontario Sewage Treatment Facilities.
38. Ibid., 32. Of the 12 plants examined, seven were operated by the province and five were operated by municipalities.
39. MOEE, Report on the 1991 Discharges from Municipal Sewage Treatment Plants, 23.
40. Ibid., 23.
41. World Wildlife Fund, Toxics from Sewage Treatment Plants, 4. Information on environmental effects from Sullivan and Krieger, Hazardous Materials Toxicology.
42. World Wildlife Fund, Toxics from Sewage Treatment Plants, 1. Many toxics cannot be “treated” or removed from effluent using current STP treatments. The focus for the reduction of toxic water pollution, therefore, should be on eliminating pollution at its source as opposed to treating it at the end of the pipe before it is released into the already damaged ecosystem. If this new focus is not adopted, taxpayers will continue to invest in a system that simply redistributes pollution.
43. Miller, Living in the Environment: Principles, Connections, and Solutions, 534.
44. Beak Consultants, Review of Aquatic Toxicity and Environmental Impact of Ontario Sewage Treatment Plant Effluents, 1.3.
45. Miller, Living in the Environment: Principles, Connections, and Solutions, 429.
46. Ibid., 429.
47. Biomagnification is the reason that advisories on fish consumption inform against eating certain species of fish contaminated with mercury, dioxin and other toxics. Miller, in Living in the Environment: Principles, Connections, and Solutions, illustrates the dangers of bioaccumulation when describing health threats of lead and dioxin. Lead is one metal that bioaccumulates in the human body where it has a half life of 20 years. That means that it takes 20 years for half of the lead stored in the bones to emit its radiation. Children with more than 10 micrograms of lead in each tenth of a litre of blood are vulnerable to damage of the brain and central nervous system, impaired memory, lower IQ scores, high blood pressure, partial hearing loss and many other damaging effects. Miller cites a 1986 Environment Protection Agency study that stated 88 percent of all children under the age of six in the United States have unsafe blood levels of lead. Dioxin, one of the most persistent and toxic chemicals, also bioaccumulates and apparently bioamplifies or biomagnifies in the food chain. In humans, dioxins promote cancer; laboratory tests have shown that this toxic has immunological, neurological, and developmental effects at low exposure levels in test animals. Dioxins have been detected in clothes and enter sewer systems when clothes are washed (World Wildlife Fund, Toxics from Sewage Treatment Plants, 10).
48. Beak Consultants, Review of Aquatic Toxicity and Environmental Impact of Ontario Sewage Treatment Plant Effluents, 1.3.
49. Conducting tests in the laboratory is the practical and economical way to study the effects of effluents for the simple reason that all the variables such as exposure time to the effluent and water temperature can be controlled. In the field (i.e., the receiving waters), it is difficult to control for the many changing conditions that threaten to invalidate the results. It is because of this that few studies have been conducted outside of the laboratory.
50. Ibid., 1.3.
51. Ibid., 8.1.
52. MOEE, Evaluation of Acute Toxicity of Ontario Sewage Treatment Plant Effluents.
53. A similar 1992 study in Alberta by Moore, Somers, Fritz, Smiley, Goski, Dew and Blumhagen investigated the toxicity of both influent and effluent from 10 STPs and found that the effluents were not toxic to four test species; however, primary lesions on the fish associated with the skin and gills developed.
54. Beak Consultants, Review of Aquatic Toxicity and Environmental Impact of Ontario Sewage Treatment Plant Effluents, 3.2.
55. John Antozek, Municipal Pollution Control Engineer, Urban Beaches Program, MOEE, supplied unpublished beach posting data for the time period from 1986 to 1994.
56. In 1991, water samples revealed 414 fecal coliforms at Bluffers beach in Scarborough, 156 at Balmy beach, 142 at Windemere beach, and 117 at Ellis Ave. beach (Toronto Star, “Four beaches ruled unsafe”).
57. Schaffer, “Beach closings rarer–not gone.”
58. John Antozek, Municipal Pollution Control Engineer, Urban Beaches Program, MOEE, supplied unpublished beach posting data. The six beaches are Amos Waites Park, Humber Bay East, Humber Bay Park West-North, Humber Bay Park West-South, Marie Curtis Park East and Marie Curtis Park West. In the summer of 1995, four of those six beaches (Amos Waites Park, Humber Bay East, Marie Curtis Park East and West) had been posted from the week of June 2 through the week of July 28, when this report was written.
59. Schaffer, “Beach closings rarer–not gone.” The western beaches are near the mouth of the Humber River where pollutants from agriculture and industry enter Lake Ontario. The effect this pollution has on the beaches is compounded by the shallow water which is warmer than other parts of Lake Ontario allowing bacteria to grow more effectively.
60. Ibid., 8.
61. Many expect Ontario’s population to grow considerably in the next decades. For example, Metro Toronto’s official plan envisions population increases of up to 600,000 people within the next 15 years (The Municipality of Metropolitan Toronto, Metropolitan Toronto Government Strategic Plan, 2). The municipality of Halton, which includes the cities of Oakville, Burlington and Milton, has estimated an increase of 200,000 in the next 15 to 20 years (Globe and Mail, “City utilities tap into private enterprise”).
62. World Wildlife Fund, Toxics from Sewage Treatment Plants, 10.
63. The Christian Science Monitor, “Britain’s Imperative to Water Industry: Clean Up Your Act.”
64. MOEE, Report on the 1991 Discharges from Municipal Sewage Treatment Plants. Although the report noted that 91 STPs were not in compliance, it listed only 90 STPs.
65. MOEE, Utility Monitoring Information System Report Type 021: Plant Performance, 1.
Beak Consultants Limited and Canviro Consultants. Review of Aquatic Toxicity and Environmental Impact of Ontario Sewage Treatment Plant Effluents. Prepared for Environment Canada and the MOEE. January 1990.
Brubaker, Elizabeth. Property Rights in the Defence of Nature. Toronto: Earthscan Publications Limited, 1995, 53-92.
Cassidy, Paul. “Outdated Federal Fisheries Act Fails Sustainable Development.”
Environmental Policy & Law 6, no. 2 (May 1995): 205.
The Christain Science Monitor. MacLeod, A. “Britain’s Imperitive to Water Industry: Clean Up Your Act.” August 3, 1994.
Estrin, David and John Swaigen. Environment on Trial: A Guide to Ontario Law and Policy. 3rd ed. A project of the Canadian Institute for Environmental Law and Policy. Toronto: Edmond Montgomery Publications Limited, 1993, 522-54.
Globe and Mail. “Philip to run Hamilton water system.” September 29, 1994.
———-. Martin Mittelstadt. “Ontario water quality questioned.” November 16, 1994.
———-. Doug Saunders. “City utilities tap into private enterprise.” May 25, 1995.
Miller, G.T. Living in the Environment: Principles, Connections, and Solutions. 8th ed. Belmont, California: Wadsworth Publishing Company, 1994, 595-614.
Ministry of Environment and Energy (MOEE). Assessment of Factors Affecting the Performance of Ontario Sewage Treatment Facilities. November 1992.
———-. Evaluation of Acute Toxicity of Ontario Sewage Treatment Plant Effluents. August 1992.
———-. Utility Monitoring Information System Report Type 021: Plant Performance, January 1993-December 1993.
———-. Water Resources Branch and Regional Operations Division. Report on the 1991 Discharges from Municipal Sewage Treatment Plants in Ontario, Volume 1–Summary of Performance and Compliance. September 1993.
Moore, J.W., J.D. Somers, D.L. Fritz, K.L. Smiley, B. Goski, B. Dew and K. Blumhagen. 1992. Toxicity of municipal wastewater to two species of fish, the cladoceran Dapnhia magna, and the mollusc Anodonta grandis. Alberta Environmental Centre, Vegreville, AB.
The Municipality of Metropolitan Toronto. Metropolitan Toronto Government Strategic Plan: Executive Summary. May 1991.
———-. The Sewage Treatment Process. Metro Works, Water Pollution Control Division, information package. January 1994.
Now. Glenn Cooly. “Should private companies own the water coming out of your taps?” May 4-10, 1995.
Schaffer, G. “Beach closings rarer–not gone.” Great Lakes Reporter, The Center for the Great Lakes, July/August 1991, 8.
Sullivan, John B. and Gary R. Krieger. Hazardous Materials Toxicology: Clinical Principles of Environmental Health. Baltimore: William and Wilkens, 1992.
Thompson, D. and A. Kuilman. “MISA Program Update.” Hazardous Materials Management, June/July 1995, 26-28.
Toronto Star. “Four beaches ruled unsafe.” June 8, 1991.
World Wildlife Fund. Toxics from Sewage Treatment Plants. Eagle’s Eye. Spring 1995.