Ecological Risk Assessment Case Study: Impacts to Aquatic Receptors at a Former Metals Mining Superfund Site

An ecological risk assessment (ERA) was conducted as part of the Baseline Risk Assessment of the Remedial Investigation (RI) for the Baxter Springs/Treece subsites, Cherokee County, Kansas Superfund site, a former metals mining site. Chemicals of potential concern were heavy metals associated with mine wastes and with base metal ore deposits that were characteristic of this area. An EPA‐approved method was used to developed site‐specific ambient water quality criteria. Ecological impacts were assessed using three complimentary approaches. First, potential chronic impacts were assessed by applying the toxicity quotient approach (i.e., a comparison of the measured concentration of site‐related metals in surface water with calculated site‐specific health‐based criteria). Secondly, semi‐quantitative comparative ecology data were used to provide a direct measure of impacts to key species. Finally, data on other factors (e.g., acclimation and tolerance evolution) that may affect the bioavailability and toxicity of site‐related metals were also considered. Information from these three sources were used to obtain a realistic picture of actual and potential population‐ and community‐level effects associated with exposure to mining‐related metals.