Canada Water Act annual report for 2016 to 2017: chapter 3

3. Canadian Environmental Sustainability Indicators

The Canadian Environmental Sustainability Indicators (CESI) program reports on the status and trends of key environmental issues. Indicators cover air quality, climate change, water quality and quantity, and wildlife and habitat.

Water quantity

The national water quantity indicator provides a summary of trends in water quantity in rivers across Canada from 2001 to 2015 (Figure 5). At the drainage and monitoring station level, the indicators provide an illustration of whether water flows were normal, low or high from 2001 to 2015.

National key results

Figure 5: Water quantity at monitoring stations, Canada, 2001 to 2015

Water quality

The program’s water quality indicator provides an overall measure of the ability of rivers to support aquatic life (plants, invertebrates and fish) at selected monitoring sites across Canada. The water quality indicator is calculated using the water quality index, endorsed by the Canadian Council of Ministers of the Environment, to summarize the status of surface freshwater quality in Canada. This indicator reflects the extent to which water quality guidelines for the protection of aquatic life are being met at selected river monitoring sites throughout Canada. Water quality at a monitoring station is considered excellent when substances in a river are very rarely measured above their guidelines. Conversely, water quality is rated poor when measurements are usually above their guidelines, sometimes by a wide margin.

The latest water quality indicator is based on data collected from 2002 to 2016 at 322 water monitoring stations across Canada and reflecting the diversity of watersheds in the country. The data were assembled from 21 federal, provincial, territorial and joint water quality monitoring programs. The national water quality indicator was calculated using a core national network of 178 river sites, selected to be representative of surface freshwater quality across southern Canada where human pressure is most intense (Figure 6a).

Water quality measured at these river sites across Canada was rated as poor at 4 sites, marginal at 28 sites, fair at 74 stations, good at 63 stations, and excellent at 9 sites. Water quality tends to be worse where there is agriculture, mining, or a combination of these with cities (mixed pressures) (Figure 6b).

Figures 6a and 6b: National freshwater quality indicator for the 2014–2015 period, Canada

Note: Water quality was evaluated at 178 sites across southern Canada using the Canadian Council of Ministers of the Environment’s Water Quality Index. Two sites have not had their land use categorized because they are close to the Canada-United States border or the ocean. They have not been included in the land use indicator. Percentages may not add up to 100 due to rounding.

Source: Data assembled by ECCC from 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.

Overall, water quality has not changed at a majority of sites across southern Canada between 2002 and 2016. Out of the 178 core sites, there was improvement in water quality at 10% of sites and deterioration at 9% (Figure 7).

Figure 7: Trends in National water quality indicator change from 2002–2015, Canada

Note: The trend in water quality between the first year that data were reported for each site and 2015 was calculated at 178 sites across southern Canada. A uniform set of water quality guidelines and parameters were used through time at each site for the trend analysis. Changes in water quality from the first year of data collected at the site to 2015 are evaluated by dividing the concentration of each water quality parameter at a site by its guideline for each sampling date. These ratios are averaged annually to obtain the deviation ratio at a site. A Mann-Kendall test was used to assess whether there was a statistically-significant increasing or decreasing trend in the annual guideline deviation ratios at a site.

Source: Data assembled by Environment and Climate Change Canada from federal, provincial and joint water quality monitoring programs.

Other water indicators can be found online.