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Context
Status
Influencing factors
What’s next?

Context

Water of sufficient quality and in adequate quantities is fundamental to ecosystems, human health and economic performance  The indicator presented in this report focuses on water quality for the protection of aquatic life, a use which is relevant to all water bodies and a broad reflection of ecosystem health. Freshwater aquatic life can be sensitive to slight changes in their environment. As a result, monitoring the environment in relation to the basic requirements of aquatic life is an effective method of assessing the overall health of freshwater ecosystems. However, water that is assessed to be suitable for aquatic life may not be so for other uses, such as drinking or livestock watering, due to the presence of, for example, pathogens or algal toxins. Thus, this indicator does not assess the quality of water for human consumption or use.

In Canada, water is mostly used by households and in industries such as electricity generation, agriculture, manufacturing, petroleum extraction and mining. In 2005, over 40 billion cubic metres of water were withdrawn from surface water and groundwater sources for industrial purposes alone (Statistics Canada 2007b). In some cases, intensive and competing water uses can lead to local shortages and can compromise water quality (Environment Canada 2004b).

Water quality can also be compromised by toxic and other harmful substances. Every day, manufacturing and service industries, institutions and households discharge hundreds of different substances, directly or indirectly, into rivers and lakes. At least 115 000 tonnes of pollutants were directly discharged to Canada’s surface waters (both freshwater and coastal) in 2005 (Environment Canada 2007c). Nitrate and ammonia were the pollutants released to water in the largest quantities in 2005 from industrial and commercial facilities; other, more highly toxic substances, such as mercury, were released in much smaller, but nevertheless significant, amounts (Environment Canada 2007c).

Many more pollutants make their way into water bodies indirectly after being released into the air or onto the land. Aquatic ecosystems receive airborne pollutants transported over long distances, such as sulphur dioxide and nitrogen oxides that cause acidification, as well as metals (e.g., lead and mercury) and organic compounds (e.g., polychlorinated biphenyls [PCBs] and pesticides). Runoff from agricultural lands and urban areas also degrades water quality (Coote and Gregorich 2000, Environment Canada 2001a). Degraded water quality can affect economic activities such as freshwater fisheries, tourism and agriculture, or recreational uses of water such as swimming.

Water quality is difficult to define and assess on a national basis. Firstly, water bodies are spread across a large geographic and geological setting. Secondly, water chemistry is complex and depends on many physical and chemical properties that vary naturally across seasons and years. These properties can affect the suitability of water for aquatic organisms, which themselves vary from place to place, have a wide range of habitat requirements and have different sensitivities to different substances. Evaluating whether water quality is degraded by human activity is further complicated by natural processes such as large quantities of rain, melting ice and snow, soil erosion and weathering of bedrock, which also influence levels of certain substances in water (e.g., nutrients, major ions and trace metals). These natural phenomena are essential to the maintenance of the habitat for a wide range of indigenous species, as well as the conditions underlying other ecosystem processes. These processes vary considerably across the country, making for a diverse mix of aquatic ecosystems.

To report on water quality, experts measure specific substances in water and compare the observed concentrations against scientifically established thresholds for potential adverse effects. These thresholds can be national or provincial in nature (referred to as national or provincial guidelines) or can be refined on a case-by-case basis to account for the presence of natural substances that may influence the toxicity of another substance (referred to as site-specific guidelines). This is the basis of the Water Quality Index (WQI) endorsed by the Canadian Council of Ministers of the Environment (CCME) in 2001 and used in this report to produce the water quality indicator (Box 4). This indicator has been calculated using the results of ongoing water quality monitoring programs managed by federal, provincial and territorial governments.

Status

National freshwater quality
Freshwater quality by major drainage area
Phosphorus, a national freshwater quality issue

Water quality data from a mix of federal, provincial, territorial and joint monitoring programs were assessed by regional experts and assembled into a national data set to calculate this indicator. Summaries were prepared for monitoring sites located in southern Canada and northern Canada (Box 5). In total, data from 395 sites (Appendix 3, Map A.2) were compiled for the 2003 to 2005 period: 36 for northern Canada and 359 for southern Canada. Further representations of the data were prepared as summaries for Canada’s major drainage areas (Map 3).

Northern areas were not included in the national indicator but reported separately because these sites were usually sampled less frequently and were less representative of the overall territory. Monitoring networks are generally designed to measure the influence of land-use activities or other stressors on water quality in order to better manage human activities and protect water resources. Hence, there is a higher density of stations in the more populated areas of the country.

The freshwater quality indicator is based on the best available information, but the concentration of monitoring stations in the more heavily settled areas of the country means that the indicator should not be interpreted as representing the state of all fresh water in Canada but, rather, water quality in specific areas of concern. In addition, all sites, whether small rivers, large rivers or lakes, are weighted equally in the indicator.

National freshwater quality

The national freshwater quality indicator shows that in southern Canada, water quality measured using the WQI for 2003 to 2005 was rated as "excellent" at 22 sites (6%), "good" at 137 sites (38%), "fair" at 119 sites (33%), "marginal" at 65 sites (18%) and "poor" at 16 sites (5%) for their suitability to protect aquatic life. The monitoring network used to generate the analysis included 10 lakes and 349 rivers (Figure 11).

Different water quality parameters were measured at different locations across the country, depending, in part, on the priorities of the various monitoring programs, the kind of human influences in the area and the characteristics of the aquatic ecosystems. However, the parameters included most often in the calculations were phosphorus (344 sites) and different forms of nitrogen: ammonia (295 sites) and nitrates (140 sites). At sites where phosphorus, ammonia and nitrate measurements were reported, they exceeded limits set under the water quality guidelines in over half the collected samples, at 37%, 18%, and 16% of sites respectively. In general, both human activities and naturally high background levels are likely responsible for exceedances of guidelines. Section 4.2.3 focuses on phosphorus as a major issue of concern with regard to surface freshwater quality in Canada based on the WQI.

In last year’s report, the freshwater quality indicator for southern Canada (2002 to 2004) was based on 340 monitoring stations. The indicator showed that water quality was "good" or "excellent" at 44% of the sites, "fair" at 34% of the sites, and "marginal" or "poor" at 22% of the sites. This 2007 report examines 359 sites, with 19 new sites for southern Canada and 323 that were in the same locations as the previous year. Due to the changes in stations and to improvements in the indicator, year-to-year comparisons cannot be made at this time. In addition, with only three reporting periods to date, it is not yet possible to derive a meaningful national trend in water quality.

Also for the 2006 report, the WQI had been calculated for seven basins in the Great Lakes region using 2004 and 2005 monitoring data. Water quality was rated as "excellent" in one basin (Lake Superior), "good" in three (Lake Huron, Georgian Bay, and the eastern basin of Lake Erie), "fair" in one (the central basin of Lake Erie) and "marginal" in two (Lake Ontario and the western basin of Lake Erie). No new data were available for updating water quality ratings for the present report. However, continuation of the monitoring program will allow for future updates.

Freshwater quality by major drainage area

New for this report is a more detailed representation of the freshwater quality indicator results, including sites from the South and the North, using Canada’s major drainage areas (Map 3). This representation is meant to provide more information on the distribution of water quality ratings across the country; it does not allow for a comparison of the major drainage areas. The set of monitoring stations located within each of the major drainage areas was not designed to be fully representative. For example, some of the areas are relatively large, such as the Arctic Drainage Area, yet have relatively few stations—making comparisons among drainage areas and general interpretations about the water quality of these areas problematical at this time. Furthermore, the parameters included in the indicator are not necessarily the same in all areas. Improvements to monitoring coverage and implementation of site-specific guidelines to reflect natural differences among ecosystems will result in more accurate water quality ratings of these major drainage areas in the future.

Phosphorus, a national freshwater quality issue

One of the major issues of concern for water quality across Canada continues to be nutrient enrichment (Chambers et al. 2001, Lowell et al. 2005, LWSB 2006, MDDEPQ 2007). Nutrients such as phosphorus and nitrogen are essential elements for the growth and survival of all organisms. An oversupply of nutrients in the environment from human activities, however, can result in excessive and noxious aquatic plant growth, a condition known as "accelerated eutrophication." In water, the decay of excess plant material can reduce the amount of oxygen available for fish and other aquatic animals. Some algal blooms can also be toxic, killing livestock and resulting in shellfish‑growing area closures, and representing a risk to human health.

In the absence of human development, phosphorus exists only in phosphate-bearing rock and is introduced into water through soil and rock erosion. Consequently, the natural level of phosphorus in water is influenced by the amounts and types of rock and soil in the area. Water bodies in regions with a lot of soil, such as the Prairies, naturally have high phosphorus levels compared to water bodies in areas with little soil, such as the Canadian Shield.

Throughout the seasons, phosphorus levels in water also exhibit changes that are strongly influenced by the annual natural water cycle. For example, snowmelt and heavy rainfall can lead to high levels of suspended sediments that are rich in nutrients. These phenomena serve important ecological functions.

Many of the water quality monitoring sites across Canada had frequent phosphorus exceedances, indicating the potentially widespread nature of nutrient enrichment (Text table 1). However, some exceedances are attributed to challenges in deriving locally relevant phosphorus guidelines that reflect the natural variation of phosphorus among sites and through the seasons.

Phosphorus releases to the environment

Expanding human populations and human activities have greatly increased the biologically available supply of nitrogen and phosphorus in the environment (Chambers et al. 2001). Phosphorus from human activities can be released from point sources, such as the end of pipes, or through diffuse sources, such as runoff from a field.The largest point source of phosphorus to marine and fresh waters in Canada is municipal sewage—contributing about 5.6 thousand tonnes in 2004, mostly from human waste. Discharge of industrial wastewater added at least another 2.2 thousand tonnes to surface waters, and aquaculture, about 1.4 thousand tonnes (Text table 2).

Agricultural activities and septic systems are indirect sources of phosphorous loading to the environment. It is possible to estimate agricultural additions of phosphorus to the soil in the form of chemical fertilizer or animal manure. For 2001, around 573 thousand tonnes are estimated to have been added to cropland in the form of fertilizer and manure (Statistics Canada 2001a, Korol 2002); crop harvesting removed around 302 thousand tonnes (Beauchamp and Voroney 1994, Bolinder et al. 1997, Statistics Canada 2001b). Septic systems are estimated to contribute about 1.6 thousand tonnes of phosphorus a year (Chambers et al. 2001, Environment Canada 2007d). Both of these sources add phosphorus to the soil, but there are no national estimates of loading to water from these sources.

The removal of vegetation along water bodies and the draining of wetlands, although not sources of phosphorus as such, contribute to phosphorus loadings indirectly by not retaining or slowing the progression of phosphorus carried by water running off the land. The use of fertilizers on residential lawns and gardens also intensifies potential phosphorus loadings to water.

Influencing factors

Natural phenomena
Human activities

Water quality can be influenced by a variety of natural phenomena and human activities, acting both at large scales (e.g., acid rain, climate) and at very local scales (e.g., waste effluents). As a result, each monitoring site has a unique set of factors influencing water quality.

Natural phenomena

In many areas, natural phenomena contributed to water quality measurements exceeding guidelines for a number of parameters. For example, glacial melt, snowmelt and heavy rainfall can lead to high levels of suspended sediments that are rich in nutrients and metals. As well, the naturally acidic water of bogs and other wetlands can result in lower pH and higher concentrations of certain metals at downstream sites. Rock and soil composition in the drainage area are also strong determinants of background levels of naturally occurring substances in water.

Human activities

The most common human activities that can influence water quality in Canada include urbanization, household behaviour related to water use, farming, industrial activity and mining production, as well as dams, and atmospheric emissions that lead to acidic precipitation. Nearly all of the southern monitoring sites and slightly more than one third of the northern sites are located within inhabited areas of Canada. Similarly, over half of the monitoring sites in southern Canada and one tenth of the northern monitoring sites fall within areas of agricultural activity. As many as 145 sites east of Manitoba are in acid-sensitive areas where deposition of sulphur dioxide and nitrogen oxides continues to be relatively high for the naturally low capacity of soils to buffer against these effects.

Although human activities are present in many monitored watersheds of Canada, management practices can control or reduce impacts on water quality. Important improvements have occurred in several industrial sectors, including pulp and paper mills and metal mines, as a result of strong regulations and cooperation between government and industry.

What’s next?

The freshwater quality indicator reported here will be improved in future reports. Work is being carried out on methods to improve the calculation and presentation of the current indicator, as there is a need to both compensate for the unbalanced geographical distribution of monitoring sites across Canada, and to present water quality trends over time.

In addition to improving the freshwater quality indicator for aquatic life, efforts are under way to develop measures that assess water quality for other important beneficial uses, including drinking water sources, agricultural uses and recreational uses. Surveys to better understand how water is used by the industrial and agricultural sectors are being conducted. A survey of public drinking water treatment plants is also being developed.

Protection of aquatic life

Environment Canada, in cooperation with the provinces and territories, will continue to work towards strengthening water quality monitoring networks, particularly in areas that have less representation (e.g., Saskatchewan, Nova Scotia and the North). In partnership with provinces, territories and other federal departments and agencies (e.g., Parks Canada, Fisheries and Oceans Canada, Agriculture and Agri-Food Canada), Environment Canada will continue to work on enhancing Canada's collective capacity to scientifically assess and report on water quality and aquatic ecosystem health through the application of physical, chemical and biological monitoring measures and approaches.

How well the WQI rates water quality depends on the use of appropriate water quality parameters and guidelines. Parameters and guidelines used in the WQI computation for the protection of aquatic life should be locally relevant, meaning appropriate to the local organisms and local water characteristics. Environment Canada, in consultation with the provinces and territories, is developing a consistent approach to site-specific guidelines across the country in order to better reflect local conditions. In particular, techniques are being evaluated to adjust current guidelines for substances that have naturally elevated concentrations. The water quality guidelines for key substances not yet included in the indicator are also under development.

Source and treated water quality

Source water is defined as "water in its natural or raw state, prior to being withdrawn for treatment and distribution as a drinking water supply." From the source water to the consumer’s tap, barriers need to be put in place to reduce or prevent contamination to the drinking water supply, and therefore protect public health. Protecting source water quality is considered the first barrier in a multi-barrier approach to safe drinking water supply (Federal-Provincial-Territorial Committee on Drinking Water and CCME 2004b).

Source water quality is considered an important asset for sustaining our health, environment and economy (NRTEE 2003). This was the basis for choosing to develop a source water quality indicator in Canada. However, source water quality is only indirectly linked to public health since almost all public water supplies treat the water before it is distributed for consumption. Therefore, to link water quality to human health, a treated water quality indicator will form another important component of this initiative.

The purpose of the source and treated water quality indicators is to provide an indication of the quality of source and treated water. These indicators will provide information for use in decision making to promote both source water protection and proper water treatment. Since 2006, work has been carried out on methodology development and two tools that will form part of the indicator calculation. 

The first tool is a calculator that compares specific parameters of water quality (source and treated) to drinking water guidelines and calculates a score between 0 and 100, based on methodology developed for the CCME WQI. An additional tool, applicable to the source water quality indicator, provides an indication of the treatment required for specific parameters of water quality to meet drinking water guidelines, and assigns a treatability ranking based on the complexity of the identified treatment.

In order to support the production of these indicators, Statistics Canada has assembled an inventory of public drinking water treatment plants. This inventory will serve as a sampling base for a survey of source and treated water quality to be conducted in the spring of 2008.  

Agricultural water

The development of an indicator to report on the suitability of water quality for agricultural uses such as crop irrigation and livestock watering will be investigated. The testing of the applicability of an indicator based on the WQI methodology will be done using a subset of relevant stations from the national indicator. A review of the current water quality guidelines for agricultural use is now under way. This analysis will help determine which guidelines need to be updated or developed for incorporation into the freshwater quality indicator for agricultural water use.

This work will be supported by a new survey: the Agricultural Water Use Survey, to be conducted in February 2008. Its objective is to collect nationally consistent data on water used for irrigation. Approximately 2000 farm operations will be asked to provide information on the source and quantity of water used for irrigation by crop type, water management techniques, treatment required, equipment used, and crop production. The results are expected to be published in the summer of 2008.

Recreational water

A preliminary investigation has been conducted to develop an inventory of Canadian monitoring programs that collect water quality information relevant to recreational water uses. These are primarily related to swimming or bathing but can include other activities such as waterskiing, windsurfing, fishing and canoeing. Guidelines for Canadian Recreational Water Quality are developed by the Federal-Provincial-Territorial Working Group on Recreational Water Quality under the authority of the Federal-Provincial-Territorial Committee on Health and the Environment, and published by Health Canada. 

Various divisions of government at all levels monitor water that is used for recreational purposes, as do certain private associations. Many of the programs reflect provincial, municipal or local needs and policies—and thus vary from jurisdiction to jurisdiction. Future work involves the examination of how the existing information may be best applied in the development of a national freshwater quality indicator for recreational water use.

Industrial water use

In 2007, results from the Industrial Water Survey provided information about the quantities of water consumed and costs, sources, treatments and discharge of water used by the primary, manufacturing and thermal-electric power industries in 2006. These results, however, did not include the oil and gas extraction sector. The next version of the survey, to be conducted early in 2008, will attempt to address this data gap.

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Notes

1. The North is delineated on Map A.2 in Appendix 3