Summary of public comments received on the draft federal environmental quality guidelines for iron

Comments on the Federal Environmental Quality Guidelines (FEQG) for Iron were submitted by Iron Ecotoxicity Research Team (Red Cap Consulting and Oregon State University), The Mining Association of Canada, Novia Scotia Environment, British Columbia Ministry of Environment and Climate Change Strategy, Alberta Environment and Protected Areas, and Ontario Ministry of Environment, Conservation and Parks.

Summarized public comments and responses are provided below, organized by topic.


Comment summary 1: Various editorial comments were received to improve the clarity and flow of the factsheet, as well as transparency and use of the information.

Response 1: Most editorial suggestions were incorporated into the factsheet, including addition of valid water chemistry ranges to which FWQG applies, additional details on methodology, and original and adjusted effect concentration values. For brevity of the factsheet, more details, such as what are FEQGs, why and when they are developed and how they differ from CEQGs, are available online. Some additional information, such as the full toxicity dataset and the evaluation of unacceptable studies, is available upon request.

Data Updates

Comment summary 2: Iron toxicity dataset and multiple linear regression (MLR) models are not sufficiently developed, however new work is underway to provide additional data and updated models.

Response 2: Newly derived data on toxicity and toxicity modifying factors, as well as updated MLR models that have been validated and published in a peer-reviewed scientific journal, were incorporated into the revised FWQG for iron.

Comment summary 3: Due to issues with phosphorus depletion in existing algal toxicity studies, it is recommended to revisit MLR model selection for the iron Federal Water Quality Guideline (FWQG) once additional toxicity studies are completed for other species (Ceriodaphnia dubia and Pimephales promelas).

Response 3: Newly published data on toxicity, toxicity modifying factors, as well as updated MLR models for invertebrates, fish and algae, were incorporated into the revised FWQG for iron.  

Comment summary 4: Suggestion to consider a field study on sensitive aquatic invertebrates.

Response 4: New data from mesocosm studies on aquatic invertebrates have been included in the revised FWQG.

Comment summary 5: Include additional surface water concentrations for iron from Ontario (ON) and British Columbia (BC).

Response 5: Additional iron surface water data for ON and BC have been included in the monitoring data table of the iron factsheet.


Comment summary 6: Discussion on the measurement of bioavailable form of iron should be added.

Response 6: Discussion on methodology for measuring bioavailable iron has been added.

Comment summary 7: Question regarding Species Sensitivity Distribution (SSD) curve-fitting methodology of non-linear least squares compared to maximum likelihood estimation.

Response 7: The revised iron FWQG uses maximum likelihood estimation to fit the SSD.

Comment summary 8: Include confidence intervals on SSD.

Response 8: Confidence intervals have been added to the SSD.

Comment summary 9: Provide a calculator for calculating guidelines.

Response 9: An Excel-based calculator has been developed and added as an appendix to the FEQG factsheet.

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