The evolution of the Canadian (CCME) Water Quality Index

ABSTRACT This paper explores the development of the Canadian Water Quality Index (CWQI) from its origins in British Columbia through to the final formulation. The CWQI was adopted in Canada in 2003 by the National Round Table on the Environment and Economy as one of six indicators for reporting on natural capital to Canadians. CWQI values are compared between 2002 and 2022. The trend in water quality between the first year that data were reported for each site and 2022 at 160 sites across southern Canada showed that there was at least some deterioration at 41% of sites, no change at 48% of sites, and an improvement in quality at 11% of the 160 sites.