Response to Critique of “The Insignificance of Thresholds in Environmental Impact Assessment: An Illustrative Case Study in Canada”

Our paper, “The Insignificance of Thresholds in Environmental Impact Assessment: An Illustrative Case Study in Canada” received a critique that challenged us on a number of grounds. Namely, that we defame EIA practitioners, that we advocate EIAs to become a scientific enterprise, that we do not recognize the complexity inherent in EIA, and that EIA undergo an independent assessment by regulators. We respond to all of these points, and argue that conflict of interest is an institutional issue (not one of corrupt practitioners), and that we critique the science that forms the basis of evidence in EIA. Further, we show that the complexity and uncertainty in the critique cannot explain the findings from our paper that all cases of impact threshold exceedance were determined to be not significant in EIA. Finally, we compare the significance determinations in proponent reports to final regulator decisions and determine that they are overwhelmingly identical (93–95%). Regulators are financially independent of proponents, but their decisions on significant are heavily dependent on the information and analysis provided by the proponent reports. As regulators rely on these reports, environmental impact assessments must be based on rigorous and transparent analysis.