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Regional Freshwater Quality in Canadian Rivers

For the 2009 to 2011 period, freshwater quality was assessed on select rivers throughout Canada where freshwater quality is at risk of being impaired by human activity.Footnote [1] The highest number of sites rated good or excellent were found in the Newfoundland–Labrador, Maritime Coastal and Saint John–St. Croix drainage regions, areas with reduced human development. In contrast, the highest number of sites with poor and marginal water quality were found in the St. Lawrence, Assiniboine–Red and Winnipeg and Great Lakes drainage regions, areas with larger human populations. Overall, rivers in the most populous regions of Canada had lower water quality exerting the greater pressure on aquatic plant and animal health.

Freshwater quality in drainage regions for the 2009 to 2011 period, Canada

Freshwater quality in drainage regions for the 2009 to 2011 period, Canada

Long Description

The stacked bar graph shows the number of sites where freshwater quality is rated excellent, good, fair, marginal and poor for the period 2009 to 2011. The map accompanying the graph displays the geographic area covered by each drainage region. The Newfoundland–Labrador, Saint John–St. Croix, South Saskatchewan and Maritime Coastal drainage regions had higher numbers of sites rated good or excellent. The St. Lawrence, Assiniboine-Red & Winnipeg and Great Lakes drainage regions had the highest number of sites with poor and marginal water quality.

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How this indicator was calculated

Note: Freshwater quality was assessed using the Canadian Council of Ministers of the Environment’s Water Quality Index. Care must be taken when comparing regions because different parameters and guidelines are used to assess water quality among provinces and territories.Footnote [2] The Winnipeg drainage region is included in the Assiniboine-Red drainage region because it contains only one site. The numbers on the map refer to the drainage region numbers on the graph.
Source: Data assembled by Environment Canada from federal, provincial, territorial and joint water quality monitoring programs.

A drainage region is an area of land where all the water on it drains into the same lake, river or ocean. Sites within a drainage region are connected by a common water source, a common geography, and the rivers that run among them. Canada has five major ocean drainage areas, which can be divided into 25 drainage regions. The drainage regions are large and are generally named for the major river or lake systems in Canada.

Freshwater quality at a site is mostly influenced by the human activity in the drainage region and the upstream water quality. Freshwater quality in the headwaters of a river is generally better than at the mouth. Human activities, such as agriculture, industry and urban development, tend to be sparser in the headwaters and to accumulate as the water moves downstream. Pesticides, fertilizers, chemical pollutants and road salt from land-based activities, as well as treated municipal and industrial wastewater, enter the river all along its course building up at the mouth of the river.

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Other information

Footnotes

Footnote 1

Water quality is assessed using the Canadian Council of Ministers of the Environment’s Water Quality Index using water quality guidelines for the protection of aquatic life. For more details about how the indicator is calculated, please refer to the Data Sources and Methods document.

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Footnote 2

For a discussion of how guidelines and parameters are chosen for a site, please refer to the Data Sources and Methods document.

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