In December 2010, the Canadian Council of Ministers of the Environment approved a new Canadian water quality guideline for uranium and it has now been posted online. The detailed supporting document is also available.

Water quality guidelines for both long-term exposure (15 µg/L) and short-term exposure (33 µg/L) were developed to protect freshwater life (plants, invertebrates and fish). Development of the Canadian water quality guideline for uranium was led by the National Guidelines and Standards Office (Emerging Priorities Division, Science and Risk Assessment Directorate), which is the federal member and technical secretariat to the Canadian Council of Ministers of the Environment Water Quality Task Group.

The long-term guidelines are intended to protect aquatic life from the adverse effects of uranium over an indefinite exposure, and it is based on a species sensitivity distribution of chronic, sub-lethal endpoints. The less-stringent short-term value that gives management guidance on the impacts of potentially severe, but transient events (e.g., spills) is based on acute, lethal data.

No Canadian water quality guideline for uranium existed previously. Environment Canada (1983) developed a guideline for surface water quality of 300 µg/L, but this value was never adopted by the Canadian Council of Ministers of the Environment and was no longer considered protective.

Contact: Susan Roe: (819) 994-8405, Science and Risk Assessment Directorate