Environmental Indicators
2 Water Quality

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Assessing water quality

Water quality is among those environmental problems most difficult to assess on a nation-wide basis. The data used in this section do not represent complete information about ambient water quality due to the lack of available data and the magnitude and complexity of measuring water quality.

The effects of both natural and manufactured contaminants upon water quality vary with water conditions (source, velocity, volume, depth, pH level), photosynthetic activity, and variations within a day as well as from season to season. In addition, inconsistencies in data collection are apt to occur due to overlapping jurisdictions and budget considerations.

Currently, there are attempts in Canada to start a national index of water quality; some regional representatives, however, are resisting the setting of national standards by a central planning committee. Due to the enormous geographic size and diversity of this country, water quality cannot be quantified effectively with one or two general measures. There are different parameters for different regions. For example, the Canadian Council of Ministers of the Environment (CCME) has decided that a Water Quality Index should be constructed by technical subgroups, one from each province and one from the federal government. In discussion, the CCME established general parameters for developing a national index of water quality in Canada.

Water pollutants

There are two sources of water pollution: point and non-point sources.9 Point sources refer to industrial discharge pipes and municipal sewer outlets that discharge pollutants directly into the aquatic ecosystem. Non-point sources refer to indirect sources of pollution such as run-off from agriculture, forestry, urban and industrial activities, as well as landfill leachates and airborne matter. Water quality also varies naturally. Some bodies of water are of poor quality due to inherent chemical, physical, and biological characteristics. Water pollution from human activities includes nutrients, heavy metals, persistent pesticides, and other toxics.

Nutrients like phosphorus and nitrogen can cause significant degradation of water quality by accelerating eutrophication,10 which depletes levels of dissolved oxygen. Phosphorus and nitrogen are found in fertilizers and livestock manure (Environment Canada 1991c: [9]26). Government regulation stipulates a reduction of the amount of phosphate in detergents in an effort to improve water quality. Lower phosphate levels in lakes and streams, however, do not always result in higher levels of dissolved oxygen and improved water quality as plants continually recycle phosphorus from sediments.

Heavy metals occur in water from the weathering of rocks. They also reach the water system directly from industrial and mining activity. Some severe cases of metal contamination are caused by abandoned mines. Non-point sources such as urban storm-water and agricultural run-off also contribute to metal contamination. High concentrations of heavy metals can affect the quality of drinking water and harm aquatic life as the metals accumulate in organs and tissues (bioaccumulation).11

Pesticides and toxics like polychlorinated synthetic compounds (DDT and PCBs) can also accumulate in biological organisms. The effects of these compounds on animals such as birds include growth retardation, reduced reproductive capacity, diminished resistance to disease, and birth deformities.

Water treatment

Industrial and municipal sewage is usually treated before being released into rivers, lakes, streams, or oceans. Primary waste-water treatment removes solid waste mechanically; secondary treatment employs biological processes to break down dissolved organic material; tertiary treatment removes additional contaminants, including heavy metals and dissolved solids.

The proportion of the municipal population in Canada provided with waste-water treatment increased from 72 percent in 1983 to 93 percent in 1994 (see figure 2.1) (Environment Canada 1988c). As figures 2.1 through 2.6 show, Quebec had the greatest increase in access to waste-water treatment: between 1983 and 1994, there was a dramatic increase of 660 percent in the proportion of the municipal population served by some form of waste-water treatment.

Figures 2.1-2.6 Percentage of Canadian municipal populations served by wastewater treatment

Source: Environment Canada 1998c.

Water quality in Canada

Canada does not have federally legislated water-quality objectives. The Canadian Council of Ministers of the Environment (CCME) established the Canadian Water Quality Guidelines in 1985 to provide a basis for designing site-specific water-quality objectives. The guidelines recommend concentrations for supporting and maintaining several categories of water use including aquatic life, drinking, recreational, agricultural, and industrial use. Water must meet requirements for biological (bacteria, viruses, protozoan), radiological (radioactive isotopes), physical (taste, odour, temperature, turbidity, colour), and chemical factors.

Provincial governments legislate standards and regulations for water quality in Canada, although the federal government offers advice and leadership. Municipalities are responsible for testing drinking water for coliforms and residual chlorine.

Detailed site-specific reports on water quality provide "snapshot" evidence that Canadian drinking water is generally good. Most Canadian municipalities treat drinking water through chlorination, ozone treatment, or ultraviolet radiation. Environment Canada conducted a four-year study of the quality of drinking water in the Atlantic provinces, which revealed that of the 150 substances tested none was present in levels that exceeded the maximum acceptable guidelines (Environment Canada 1990a). A study carried out in 1986 by the Canadian Public Health Association showed that levels of very few of the 161 substances measured in treated tap water from the Great Lakes exceeded the guidelines (Canadian Public Health Association 1986). Further, a 1990 study of the Great Lakes by the Toronto Board of Health could detect only 42 of the substances for which they were testing; none was present in levels that exceeded the guidelines (Kendall 1990).

Although raw data on Canadian water quality exist in a federal database, the information is not in a format that can be used to evaluate water quality on a national level. The provinces, however, are taking a greater role in monitoring water quality. British Columbia, Alberta, Saskatchewan, Manitoba, and New Brunswick have developed site-specific objectives and maintain a record of goal attainment.

The provinces test water at sites located upstream or downstream from urban centres and industrial facilities, on transboundary rivers and streams, and on bodies of water that are used for recreation. Figure 2.7 illustrates the success of British Columbia, Alberta, Saskatchewan, and Manitoba in attaining water quality objectives. It should be noted that the number and type of bodies of water tested, and of pollutants examined, varies from province to province and within provinces from year to year. Details of provincial reporting are described below.

Figure 2.7 Water Quality in Canada

Sources: Swain 1997; Saffran 1999; Hallard 1997; Williamson 1997; Choate 1997; Jain 1999.

British Columbia

There are two general measures for assessing water quality in British Columbia. The province has published objectives and attainment records for water quality since 1987 based on the British Columbia Surface Water Quality Objectives (see figure 2.7). Since 1985, the province has jointly operated federal-provincial monitoring stations in partnership with Environment Canada under the Canada-British Columbia Water Quality Monitoring Agreement.

A new report on water quality, the 1996 British Columbia Water Quality Status Report, reviews the quality of 124 bodies of water including river sections, lakes, marine bays or inlets, and ground-water aquifers. This report provides a detailed index developed from objectives and attainment records (including the number, frequency, and magnitude of objectives exceeded), rating bodies of water as "poor," "borderline," "fair," "good," or "excellent." These are described in the report as follows.

Excellent (0-3) means all uses of water are protected and none are threatened or impaired. Good (4-17) means all uses are protected with only a minor degree of threat or impairment. Fair (18-43) means most uses are protected but a few are threatened or impaired. Borderline (44-59) means several uses are threatened or impaired. Poor (60-100) means most uses are threatened, impaired or even lost. (British Columbia Ministry of Environment, Lands, and Parks 1996)

The report rated only nine of 124 water bodies as borderline or poor; nine were rated excellent, 44 were rated good and 62 were rated fair. (see figure 2.8). Unfortunately, although data from previous years have been collected, they are not reported in this format, making analysis of trends impossible.

Figure 2.8 Summary of Water Quality in Selected Bodies of Water in British Columbia

Source: British Columbia Ministry of Environment, Lands, and Parks 1996.

The report describes the source of threats to water quality and recommends methods for maintaining and restoring the quality of British Columbia's water. Of all Canadian provinces, British Columbia has developed one of the most comprehensive monitoring and reporting program on water quality (British Columbia Ministry of Environment 1993: 2-45; Rocchini 1996).

Levels of toxic contaminants in British Columbia have been decreasing over the last 20 years. As figure 2.9 shows, samples taken from the eggs of a colony of Great Blue Herons located near the University of British Columbia show a marked decline in levels of PCBs, DDE, dioxins, and furans. Between 1977 and 1996, PCBs decreased by 55.8 percent and DDE by 62.5 percent. (PCBs and DDE are discussed in greater detail in the Great Lakes section of this report.) Dioxins and furans are the chemical by-products of a number of industries including pulp-and-paper production. The 95.4 percent decrease in levels of these contaminants between 1982 and 1994 is due in part to recent changes to processes in the pulp-and-paper industry and to a reduction in contaminated effluent entering the province's waterways.

Figure 2.9 Status and trends in contaminants in great Blue Heron eggs from a colony at UBC

Source: BC Ministry of Environment, Lands and Parks 1999.

Alberta

On any given year, water quality is assessed at over 300 sites throughout Alberta. Twenty of these stations make up Alberta's long-term river network. These sites, some of which have been active for almost 30 years, are sampled on a monthly basis and tested for an extensive list of water-quality variables. Data from 12 of these stations, representing the province's six major river systems, are currently used for the Alberta Surface Water Quality Index. The Index is calculated by comparing the results of tests for 20 substances to the Alberta Ambient Surface Water Quality Interim Guidelines. Subsets of these variables are used to determine the suitability of river water for recreational and agricultural uses, and for the protection of aquatic life. The stated goal is to bring water quality downstream of developed areas in line with the water quality upstream. The index uses four arbitrary categories to describe quality according to the percent of tests meeting guidelines at each site: "good" (96-100 percent), "fair" (86-95 percent), and "not acceptable" (70 percent and below).

Alberta's Index is currently being revised to include a new set of variables and guidelines. The formula is also being changed to include the number of variables not meeting guidelines and the amount by which they do not meet guidelines as well as the percent of all tests that do not comply with guidelines. The rating system for the new index will also change (Saffran 1999).

Saskatchewan

The Saskatchewan Surface Water Quality Objectives are used as a guide in assessing the quality of surface water in the province. Priority is given to rivers affected by populated centres and locations where water quality might be threatened. Saskatchewan collects data from 15 regularly monitored stations that test for 70 pollutants (there are numerical guidelines for acceptable levels of some of the pollutants only). Sites are monitored on a monthly basis for nutrients, salts, and bacteria, on a quarterly basis for metals, and three times per year for certain pesticides. Saskatchewan continues to monitor for long-term trends and admits that this data cannot be considered reflective of overall water quality but gives instead a "snap shot" of water quality in the major rivers of southern and central Saskatchewan (Hallard 1997). A recent study of ground water examined the contamination of well-water by pesticides. This is of concern because 45 percent of Sask­atchewan residents rely on private wells for drinking water. The study determined that although one or more pesticides were detected in all but two of the wells, all concentrations were significantly lower than the maximum acceptable under the Guidelines for Canadian Drinking Water Quality (McKee 1999).

Manitoba

Manitoba's goal in monitoring water quality is to identify changes between upstream and downstream locations and to develop focused maintenance and protection programs. The results are cross-referenced with Canadian Water Quality Guidelines and Manitoba Water Quality Objectives. Manitoba uses, with minor modifications, the water quality index developed by British Columbia; as applied by Manitoba this index considers 25 variables. Manitoba monitors up to 70 water-quality variables at 35 sites located on 28 rivers and lakes. Using the category descriptors "poor," "marginal," "fair," "good," and "excellent," it assigns a ranking based on the number of objectives met, and the magnitude and frequency of exceedences, i.e., incidents when pollution exceeds objectives (Williamson 1996).

Manitoba is particularly concerned about the effects on water quality of the larger facilities for intensive production of livestock and value-added food processing facilities. Programs are underway to reduce the impact of food-processing waste and to assist the irrigating community in developing sustainable irrigation practices. Many Manitobans who reside outside municipal water systems rely on their own water supply and changes in water quality affect these people and their livestock directly. The water quality trend in Manitoba has changed little from 1991 to 1995: 96 percent of monitoring sites remain steadily at the high end of the "fair" rating (see figure 2.10). The overall rating for the Red River tends to be of slightly poorer quality downstream of Winnipeg than upstream but also remains at the high end of "fair." Flooding of the Red River in 1997 slightly elevated fecal coliform levels and there were trace concentrations of several organics; nevertheless, bacterial levels remain relatively low at all sites (Williamson 1997).

Figure 2.10 Water-Quality Index Summary for the Prairie Ecozone in Manitoba, 1991-1995

Source: Manitoba Environment 1997.

Ontario

Ontario has performed periodic water-quality assessments at specific sites; the Toronto waterfront is one example. Although there is no federal-provincial agreement on water quality, there is cross-border cooperation on water quality in the Great Lakes between the Canadian and American federal governments through the International Joint Commission (IJC), an advisory group of Canadians and Americans. Ontario has 250,000 bodies of water and measures from 10 to 200 variables of water quality at thousands of sites. Four databases contain raw data: Great Lakes, Inland Rivers and Streams, Inland Lakes and Drinking Water Surveillance. The raw data, however, have not been compiled in a form that can be analyzed to determine general trends in water quality.

The Drinking Water Surveillance Program conducted 245,000 tests in 1996 and 1997 and 99.98 percent of the sites tested met the health related drinking water objectives (Ontario Ministry of the Environment 1998).

Quebec

Quebec is the first province to carry out an overview of the status and trends of the water quality of its rivers. The Ministry of the Environment and Wildlife operates 386 monitoring stations located in 40 watersheds to measure nitrogen, phosphorus, fecal coliforms, pH, turbidity, and suspended solids. These readings, as well as biological surveys and measurements of toxic chemicals in fish, artificial substrates and water are conducted on a monthly basis. The province does not set water quality objectives but instead studies point sources to determine the nature of local or regional use of the water body and how it must be preserved or restored. Goals can vary from one site to the next on the same river as the use of that river changes.

Since 1978, Quebec has committed more than $6 billion towards improving waste-water treatment. The successes of the program are evident in the 660 percent increase between 1983 and 1994 in the proportion of the municipal population served by some form of waste-water treatment. Phosphorus loading from municipal wastewaters has decreased by an estimated 55 percent between 1979 and 1994. Improvements to treatment of mill effluents in the province's pulp and paper industry have also contributed to an improvement in water quality, leading to a 75 percent decrease in loading by suspended particles from 1980 to 1994 (Painchaud 1997).

New Brunswick

New Brunswick has not developed provincial objectives. At the moment, monitoring data is usually compared with the Canadian Water Quality Guidelines for aquatic life. New Brunswick examines 32 variables in various lakes and rivers throughout the province. Data is collected from base-line stations providing data over the long term, stations providing background information for specific projects in the short term, and downstream stations measuring the effects of point and non-point sources of pollutants. Natural waters in many areas tend to be poor in nutrients (especially phosphorous) and acidic--some natural pH values fall below the Canadian Water Quality Guideline of pH 6.5. Naturally high levels of aluminum and iron often exceed the guidelines (Choate 2000).

Newfoundland

The province of Newfoundland monitors up to 35 water-quality variables at approximately 56 sites located on rivers and lakes throughout the province. The goals of the monitoring program include collecting data on background and ambient water quality of major rivers and basins, detecting and measuring trends in water quality, and assessing fresh-water aquatic health and the suitability of water for various beneficial uses. Newfoundland maintains its own water-quality database, which is updated every two to three years. A report, the State of Water Quality in Newfoundland, based on the water quality index developed by British Columbia, is currently under preparation (Goebel 1997).

Nova Scotia

Nova Scotia follows the Canada Water Quality Guidelines but has not set site-specific objectives. It does not perform ambient monitoring but uses short-term projects to monitor and improve the water in problem areas. Residents rely equally on surface and ground water for drinking and Nova Scotia's drinking water is generally good. Concerns specific to certain areas arise primarily due to mining and industrial activity (Cameron 1996).

Prince Edward Island

Prince Edward Island has not established water-quality guidelines of its own but uses the national water-quality criteria as developed and maintained by CCME. Currently, 26 sampling sites are located in 6 watersheds. Residents of Prince Edward Island rely exclusively on ground water for drinking water, which is judged according to national guidelines developed jointly by Health Canada and the provinces. In 1996, "Evaluation and Planning of Water Related Monitoring Networks on PEI" was incorporated into a new agreement, the Canada-PEI Water Annex to the Federal/Provincial Framework Agreement for Environmental Cooperation in Atlantic Canada, between Environment Canada and the province's Department of Fisheries and Environment. In January 1996, Prince Edward Island signed an agreement with the federal government to establish a Watershed Inventory Project to examine 12 watersheds incorporating 26 rivers. Initiatives include a multi-year, program to sample drinking water for pesticides according to several parameters, and the release of an educational booklet entitled Water on PEI: Understanding the Resource, Knowing the Issues (Raymond 1997).

Yukon

The Department of Indian Affairs and Northern Development (DIAND) manages the water resources of the Yukon Territory. Water-quality objectives have not been set for any water bodies as most water bodies in the region are considered pristine. DIAND and Environment Canada jointly operated 19 monitoring stations in 1996. Baseline monitoring of rivers and streams was ended in September 1996 in preparation for the end of the Arctic Environmental Strategy of the Canadian government's Green Plan. Raw data is collected but has not been correlated into readable information due to budgetary constraints. Prevention of pollution through enforcement of water-use licenses is the sole strategy used to maintain water quality. Most communities treat sewage in lagoons, discharging it to ground or wetlands; two communities discharge treated sewage to surface water (Whitley 1997).

Northwest Territories

The water-quality objectives of the Northwest Territories comply with the CCME water-quality guidelines and site-specific water-quality objectives. DIAND and the Territory's Department of Environment currently cooperate in maintaining 50 active federal, federal-territorial, and territorial stations that monitor water quality. The federal government has collected data on 30 to 60 variables from about 100 stations reporting on 80 bodies of water in the Northwest Territories. Site-specific objectives have been established in some locations to account for unique natural occurrences and human activity. Several individual reports have been generated from the data (Haliwell 1997).

The Great Lakes

The Great Lakes (from west to east, Lakes Superior, Michigan, Huron, Erie and Ontario) are the largest system of fresh surface water on earth, containing roughly 23,000 km3 of water or 18 percent of the world's supply (GC & USEPA 1995). Due to the vastness of this resource, the lakes provide tremendous economic and ecological benefits to the surrounding area. The Great Lakes basin, which includes the lakes and over 760,000 km2 of land that drains into them, has a large concentration of industrial capacity, housing one-quarter of American industry and almost 70 percent of American and Canadian steel mills (USEPA 1995: 496). It also supports a large agricultural base: nearly 25 percent of Canadian agricultural production and 7 percent of American production is located in the basin (GC & USEPA 1995). In addition to economic benefits, the Great Lakes provide drinking water for over 23 million people and support recreation and a variety of other uses for the one-tenth of the United States' population and the one-quarter of Canada's population who live in the basin (GC & USEPA 1995).

Although for many years it was believed that the Great Lakes were too big to develop serious pollution problems, modern settlement did initially cause deterioration in water quality. Agricultural development increased the amount of silt and nutrients in streams and along shorelines, and growing urbanization and industrialization produced large amounts of waste water and toxic contaminants that were discharged directly into the lakes. As a result, by the 1960s, sewage, fertilizer run-off, and chemical wastes had caused serious degradation to Lake Erie, and the other lakes showed signs of similar trouble.

As a result of the water degradation, there have been a variety of pollution abatement initiatives at both the regional and international level over the past 30 years. In 1972, the Great Lakes Water Quality Agreement (GLWQA) between the United States and Canada set a management framework for controlling pollution, researching problems, and measuring progress. It focused primarily on targeting levels of phosphorous discharged in the lakes. Revisions to the GLWQA in 1978 and 1987 broadened the mandate to the whole ecosystem, focusing on the impacts of both point and non-point pollution on all living organisms. Since 1994, the over-all conditions and trends of a variety of indicators developed to evaluate the state of the Great Lakes ecosystem have been examined through the biennial State of the Lakes Ecosystem Conferences (SOLEC). The findings from these conferences are summarized and made available to the public through the State of the Great Lakes Reports.

In addition to developing better mechanisms to evaluate trends in the Great Lakes, the GLWQA has developed action plans to restore the Great Lakes. The two main programs are Lakewide Management Plans (LaMPs) and Remedial Action Plans (RAPs). Lakewide Management Plans (LaMPs) were created to address the most critical pollutants that affect whole lakes or large portions of them. Remedial Action Plans (RAPs) are more regionally focused. They are designed to rehabilitate the 43 Areas of Concern (AOCs). AOCs are designated geographical areas where several beneficial uses, such as fishing or swimming, are impaired. There are currently 42 AOCs: 11 located in Canada, 26 in the United States, and 5 in connecting channels. These programs continue today alongside a variety of other local initiatives run by numerous grass-root organizations and special-interest groups.

Through these efforts, water quality has improved. Levels of toxic contaminants released into the basin have steadily decreased and some key contaminants are no longer released at all. There have been note-worthy reductions in organic material, solids, and phosphorous as well. As a result of the RAPs, the harbour in Collingwood, Ontario, which was once identified as an AOC, has been successfully restored.

Despite these improvements, most regulatory bodies and environmental groups call for further action to improve water quality in the Great Lakes. The International Joint Commission (IJC), an advisory group of Americans and Canadians, states in the introduction to their Ninth Biennial Report on Great Lakes Water Quality (1998) that, although concern about phosphorous has largely been addressed and solved, concern about toxic substances has not. Similarly, the USEPA's National Water Quality Inventory recognizes the improvements in water quality but states that less visible problems, such as unfavourable conditions for aquatic life, continue to degrade the Great Lakes. The State of the Great Lakes Report also illustrates that many indicators are improving but are still not at the "good" level.

In this section, to evaluate trends in Great Lakes water quality, two main pollutants are examined: toxic contaminants and excess nutrients. The importance of measuring these pollutants to determine water quality is explained in the previous section. Trends examined in the 1997 edition of State of the Great Lakes are also discussed. These indicators focus both on reducing specific pollutants and on minimizing the negative impacts of pollution on human and wildlife populations.

Trends for toxic contaminants

The levels of pesticide contamination found in herring gull eggs fell considerably between 1974 and 1996.12 The concentration of Dichloro-diphenyl-dichloro-ethylene (DDE)13 fell 86.4 percent in Lake Ontario and 82.6 percent in Lake Superior from peak levels in 1975 (figure 2.11). In Lakes Huron and Erie, DDE concentration levels fell 88.4 percent and 82.5 percent respectively. Lake Michigan, likewise, had a 81.7 percent reduction between 1977 and 1996.14

Figure 2.11 DDE Levels in Herring Gull Eggs in the Great Lakes

Source: Council on Environmental Quality 1996: 334-38.

Levels of polychlorinated biphenyls (PCBs)15 and hexachloro-benzenes (HCBs)16 also showed drastic reductions during the same periods. PCBs fell 89.4 percent in Lake Ontario, 85.8 percent in Lake Huron, 79.7 percent in Lake Superior, 80.8 percent in Lake Michigan, and 78.6 percent in Lake Erie (figure 2.12). The level of hexachloro-benzenes (HCBs) peaked in 1977 and fell 95.0 percent in Lake Ontario, 91.9 percent in Lake Erie, and 83.3 percent in Lake Michigan by 1996. Decreases in Lakes Superior and Huron were 84.6 percent and 78.9 percent, respectively, between 1974 and 1995 (17

Figure 2.12 PCB Levels in Herring Gull Eggs in the Great Lakes

Source: Council on Environmental Quality 1996: 334-38.

Figure 2.13 HCB Levels in Herring Gull Eggs in the Great Lakes

Source: Council on Environmental Quality 1996, 334-338

Even with these improvements, there are still concerns about the level of toxic contaminants in the Great Lakes. PCB concentrations in fish in various areas of the basin continue to exceed the International Joint Commission's objective of 0.1 mg of PCBs per gram of fish tissue. Restrictions on the consumption of fish also remain in all of the Great Lakes and contaminated sediments remain in some local areas (Environment Canada & USEPA 1995b: 3, 25). There is also concern about the presence of other toxic contaminants. Including the pollutants mentioned above, scientists have detected 362 contaminants in the Great Lakes (32 metals, 68 pesticides, and 262 other chemicals). One-third of these contaminants have acute or chronic toxic effects (Environment Canada & USEPA 1995b: 3). As a result of these concerns, many regulatory agencies recommend further reduction in contaminant concentrations.18

Trends for nutrient levels

Annual phosphorous loadings have decreased in all the Great Lakes (figure 2.14). Between 1976 and 1991, total phosphorous loadings decreased by 27.9 percent in Lake Erie and 17.5 percent in Lake Ontario. Reductions in Lakes Superior, Huron, and Michigan were 24.0 percent, 7.1 percent, and 47.7 percent, respectively. Lake Superior and Lake Michigan have met their target load levels to prevent excessive algal growth since 1985 and 1981. Lakes Huron, Erie, and Ontario met their targets in 1989 and 1990 but have since experienced increases in total loadings.19

Figure 2.14 Total Phosphorous Loadings for the Great Lakes 1976-1991

Source: Richardson 1999.

These improvements have come about to a large degree because of reductions in municipal phosphorous loadings. Municipal phosphorous discharges decreased by 71.4 percent in Lake Erie, 46.4 percent in Lake Ontario, 29.2 percent in Lake Huron, 72.0 percent in Lake Michigan and 11.9 percent in Lake Superior between 1976 and 1991 (see figure 2.15; Richardson 1999). This is largely because of limits placed on the phosphorous concentration in detergents in 1972; 70 percent of total inputs of phosphorus are from detergents from municipal wastes (Environment Canada & USEPA 1995a: 3). Other reductions can be attributed to better control practices in industrial processes and agriculture.

Figure 2.15 Municipal Phosphorous Loading for the Great Lakes, 1976-1991

Source: Richardson 1999.

As a result of these reductions, spring phosphorous levels have decreased. These reductions were 59.6 percent in Lake Ontario between 1971 and 1993 (figure 2.16).20 This, in turn, has led to a decrease in the amount of algal bloom, which is measured by the amount of chlorophyll a present in the lakes. In Lake Ontario, the amount of chlorophyll a decreased by 54.3 percent between 1975 and 1993 (Richardson 1999). Since 1980, the Upper Lakes have reduced levels of algal biomass below 2.0 mg/L, the level defined as below that of nuisance condition (Environment Canada & USEPA 1995a: 9). Lake Ontario met this goal from 1987 to 1991. Eutrophication or undesirable algae, however, still present problems in 18 of the 43 areas identified by the IJC as having the most severe problems (Environment Canada & USEPA 1995a: 10).

Figure 2.16 Spring Total Phosphorous Trends

Source: Richardson 1999.

Nitrogen levels have also increased since 1971 (figure 2.17). Between 1971 and 1993, nitrogen levels increased 49.8 percent in Lake Ontario. Despite these increases, levels remain well below the threshold of 10 milligrams per litre for safe drinking water.

Figure 2.17 Nitrate/Nitrite Concentrations in the Great Lakes

Source: Richardson 1999.

Trends from State of the Great Lakes
1997 Report

The State of the Great Lakes 1997 report, illustrates an overall improvement in the Great Lakes. Table 2.1 illustrates the indicator ratings and trends for the Great Lakes aquatic near-shore ecosystem.21 For this report, each indicator is first classified as "good," "mixed," or "poor." These ratings reflect the impact of the stressors on the ecosystem. A poor rating means there is a significant negative impact; a rating of mixed tells us that the impact is less severe; and good indicates that the impact or stress is removed and that the state of the ecosystem component is restored to a presently acceptable level (Environment Canada & USEPA 1997b: 13-14).

Source: Environment Canada & USEPA 1997b: 25, table 4.

As illustrated in table 2.1 most indicators for the near-shore aquatic ecosystem are showing improvement. Similar to the trends discussed above, levels of toxic substances and nutrients are improving. Advisories on the consumption of fish and the status of native species and their habitats are also showing improvement. Fish have returned to some harbours from which they had all but disappeared,22 and the number of double-crested cormorants, a water bird that all but vanished from the Great Lakes in the 1970s, has climbed to 12,000 nesting pairs (USEPA 1995e: 497). Overall, the state of the Great Lakes aquatic near-shore ecosystem is rated in mixed condition and improving.

In the report, other indicators also show improvements in the Great Lakes. In the land-use indicators section, wastewater quality and sewage quality, based on nutrient and toxic loadings, are classified as mixed and improving. Ground-water quality, based on area and the number of contaminated wells is mixed and deteriorating although the area and number of overall contaminated sites is mixed and improving (Environment Canada &USEPA 1997b: 37).

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