Page 4: Guidelines for Canadian Drinking Water Quality: Guideline Technical Document – Selenium
Part I. Overview and Application (continued)
Note: Specific guidance related to the implementation of drinking water guidelines should be obtained from the appropriate drinking water authority in the affected jurisdiction.
The maximum acceptable concentration for selenium is established based on chronic symptoms of selenium toxicity in the general population. Short-term exceedances slightly above the guideline value are unlikely to have an effect on health.
Frequent monitoring of naturally-occurring selenium levels is generally not required, as these levels are not expected to change rapidly. Since the potential release of selenium is likely to be into source waters through coal ash pond effluent and the ash and dusts that settle on water, monitoring of source water near coal-fired power plants and in areas where mining and refining of copper and other metals occurs is recommended. In the event that monitoring data show elevated levels of naturally-occurring selenium, it is suggested that a plan be developed and implemented to address these situations.
Date reviewed: 2026-06-04