Monitoring Sublethal Toxicity in Effluent Under the Metal Mining EEM Program

The second national application of environmental effects monitoring (EEM) in Canada will be under the amended Metal Mining Effluent Regulations (MMER). Under the EEM program, sublethal toxicity testing will be included in a suite of complementary tools to assess whether fish populations, fish habitat, and use of the fisheries resource, are protected in water bodies receiving mining effluent. The rationale for including sublethal toxicity tests was provided by an extensive literature review during the Aquatic Effects Technology Evaluation (AETE) program that showed 84% agreement between sublethal toxicity test results and observed impacts on receiving water. In addition, laboratory testing during the AETE program identified tests which would be the most cost effective and efficient in assessing mining effluent toxicity. Based on the findings of the AETE program, the multistakeholder EEM Metal Mining Working Group and its Toxicology Subgroup selected tests on fish, invertebrates, algae and an aquatic plant species, and developed consensus recommendations on the minimum requirements for sublethal toxicity testing and technical guidance on how to implement the recommended monitoring. The rationale for method selection and application of test results, and general testing requirements are discussed.