Water Quality Index

Calculate the Water Quality Index for a given station/site

The WQI is used across Canada as a standardized approach to roll-up status of multiple water quality parameters at a site and communicate the ‘state’ in a simple manner. The WQI focuses on water quality with respect to the health of freshwater aquatic health. The WQI approach is documented on the CCME website, including detailed methods, a list of established national parameter guidelines/thresholds, and a point and click MS Excel Calculator (http://www.ccme.ca/en/resources/canadian_environmental_quality_guidelines/index.html). A version of this method is also employed by Environment Canada’s Canadian Environmental Sustainability Indicator program (example of outputs, final product and details of the methods employed by CESI here: http://www.ec.gc.ca/indicateurs-indicators/default.asp?lang=En&n=CB97D13E-1). Number of parameters with exceedances, the number of exceedances and the magnitude of exceedances (from (1), above) are used to generate a score (0 to 100) which is then converted to a ranking of quality (poor, marginal, fair, good, and excellent). Outputs of the WQI analysis should include a summary results table with scores and final category for each site, facet graphs of parameters with superimposed WQI results (e.g. data, horizontal threshold line and exceedances visible), and, if possible, a British Columbia map with colour-coded points denoting the water quality index status for each station/site. A shape file for creating provincial boundaries is available.