Land Use Impacts on Freshwater Quality

For the 2009 to 2011 period, freshwater quality was assessed by land use category to better understand how water quality is impacted by land-based activities, such as agriculture and mining. Good to excellent water quality was found in 25% of sites with little human development (Remote), 8% of sites with agriculture only, 8% of sites having a mix of agriculture, mines and cities (Mixed) and 7% of sites with mines. Marginal to fair water quality was found at 20% of sites classified with mixed land use, 14% of sites with agricultural land use, 8% of sites with mines and 8% of remote sites.

Overall, sites with agriculture and mining development are more likely to have impaired water quality, particularly when they have more than one type of land use. Remote sites generally have better freshwater quality.

Freshwater quality by land use category for the 2009 to 2011 period, Canada

Freshwater quality by land use category for the 2009 to 2011 period, Canada

Long Description

The bar graph presents the number of sites where freshwater quality for the protection of aquatic life is rated excellent, good, fair, marginal and poor in the four land use categories between 2009 and 2011. The four land use categories are: agriculture, mining, mixed pressures and remote. Good and excellent freshwater quality was found significantly more often in remote areas.

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How this indicator was calculated

Note: Freshwater quality by land use category was assessed at 166 sites throughout Canada’s 16 drainage regions where human activity is most intensive using the Canadian Council of Ministers of the Environment’s Water Quality Index. Six sites have not had their land use categorized and are not included in this indicator.
Source: Water quality data were assembled by Environment Canada from existing federal, provincial, territorial and joint water quality monitoring programs. Population, mining and land cover statistics for each site’s drainage area were provided by Statistics Canada.

Land use, or how humans have developed and managed land around a river, affects freshwater quality. Water running off of agricultural fields and city streets and discharged from mines or wastewater treatment plants can decrease freshwater quality in nearby rivers. In contrast, freshwater quality in remote areas is mainly determined by local soil conditions and tends to be rated excellent or good, given there is less human development and rivers are surrounded by plants and trees. Marginal or poor water quality can, however, occur in these areas, due to pollution travelling long distances through the air.

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