Data Sources and Methods for the Freshwater Quality Indicator

2.1  Description

The Freshwater Quality Indicator (WQI) provides an overall measure of the ability of freshwater bodies to support aquatic life at selected monitoring stations across Canada. It is a water quality guideline-driven tool used to distill large amounts of water quality data at a monitoring station into a single index. Water quality at a monitoring station is considered excellent when ambient water quality does not exceed guidelines at any time for any of all selected parameters.

2.2  Rationale

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

2.3  Changes since last report

An analysis of changes through time was added to track how the national WQI has been changing since 2003. The analysis identified the number of stations where the WQI was improving or deteriorating and where no change was detected.