Application of CCME Procedures for Deriving Site-Specific Water Quality Guidelines for the CCME Water Quality Index

Abstract

Since its development in 2001, the Canadian Council of Ministers of the Environment (CCME) Water Quality Index (WQI) has established itself as a valuable tool for communicating ambient water quality data. Due to the high natural background levels of particular parameters in water bodies throughout the country it is often necessary to use Site-Specific Water Quality Guidelines (SS-WQGs) as opposed to generic national Water Quality Guidelines (WQGs) or provincial Water Quality Objectives (WQOs) in the CCME WQI model to obtain truly representative rankings. SS-WQGs have only been developed for a limited number of ambient water quality sites and this has been a major hurdle to the widespread use and acceptance of the CCME WQI. This paper presents the adaptation and implementation of an existing CCME-approved SS-WQGs derivation method called the background concentration (BC) procedure into a Site-Specific Water Quality Index (SS-WQI) calculator and tool. It discusses the application of the SS-WQI calculator to compute water quality indices for five pristine ambient water quality sites in Newfoundland and Labrador. The effects of using five different BC-based SS-WQGs (mean; median; mean ± one standard deviation; mean ± two standard deviations; 90th and 10th percentile) are examined. The paper also discusses the challenges and benefits of using this methodology and provides recommendations for further testing.

Comparative analysis of regional water quality in Canada using the Water Quality Index

“…In many instances, water quality managers are limited by a lack of WQG for certain variables (Glozier et al 2004 or by numerical limits set by the CCME guidelines, whereby background concentrations of variables are often higher than the recommended guidelines in pristine watersheds (Khan et al 2005;Mercier and Léger 2005). Furthermore, the CWQG for the protection of aquatic life may not be the best application of the CCME WQI to assess spatial changes in water quality.…”

“…While the first three are largely contingent upon the designs of the monitoring program, the selection of appropriate guidelines and/or objectives is crucial to calculating representative and accurate water quality indices (CCME 2001;Khan et al 2005;Mercier and Léger 2005).…”

“…Other water quality guidelines have been developed to assess water quality for drinking, recreational, and agricultural uses. Water quality guidelines have been applied to the CCME WQI when reporting on the status of watersheds for protection of aquatic life (Glozier et al 2004;Khan et al 2005;Lumb et al 2006) or for specified uses such as drinking, recreational and agricultural (Khan et al 2003(Khan et al , 2004Environment Canada 2005;Glozier et al 2006).…”

“…Site-specific objectives have been applied to the CCME WQI to assess watersheds in the Atlantic Region (Khan et al 2003), Banff and Jasper National Parks (Glozier et al 2004), Manitoba , and the Mackenzie River Basin (Lumb et al 2006). Khan et al (2005) modified the CCME WQI calculator to include site-specific objectives that were derived from the 90th percentile of monitored data. This modified site-specific WQI calculator was programmed to use site-specific objectives where natural concentrations were higher than the CWQG for the Protection of Aquatic Life and defaulted to the CWQG when background concentrations were lower.…”

“…This modified site-specific WQI calculator was programmed to use site-specific objectives where natural concentrations were higher than the CWQG for the Protection of Aquatic Life and defaulted to the CWQG when background concentrations were lower. By using the modified site-specific WQI method, Khan et al (2005) demonstrated that this method more accurately reflected water quality for five pristine watersheds in Newfoundland and Labrador.…”