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Data Sources and Methods for the Freshwater Quality in Canadian Rivers Indicator

2. Description and rationale of the Freshwater Quality in Canadian Rivers indicator

2.1 Description

The Freshwater Quality in Canadian Rivers Indicator (WQI) is designed to provide an overall signal of the ability of ambient water in select rivers across Canada to support aquatic life. The data for the national and regional WQI is collected at a subset of monitoring sites across Canada (core sites) in 16 drainage regions where human activities result in a high potential of impaired water quality. It is a water-quality-guideline-driven tool used to distill large amounts of water quality data at a monitoring site into a single index.

Water quality at a monitoring site is considered excellent when ambient water quality never, or very rarely, exceeds guidelines for any selected parameters. When water quality is rated poor, water quality measurements usually exceed their guideline; exceedances at these sites may be large.

2.2 Rationale

Clean water is essential to sustain healthy ecosystems and the many benefits they provide us. The WQI provides a national perspective on the overall quality of freshwater for aquatic life in Canada. The WQI assumes that, if measured ambient water quality does not exceed its water quality guideline, it is acceptable for aquatic plants and animals. The WQI provides information about the state of surface freshwater quality and its change through time to inform water resource management.

2.3 Recent changes to the indicator

One core site in Ontario has been removed from the analysis because monitoring at that site ended in 2011.