Application of Habitat Suitability Index Values to Modify Exposure Estimates in Characterizing Ecological Risk
SourceWe developed an approach intended to improve the accuracy and relevancy of ecological risk assessments (EcoRA), facilitate communication of decisions, and control overall project costs. An Access® database containing data for 91 Habitat Suitability Index (HSI) Models species and a Correspondence Matrix, which cross-lists all wildlife species of the US in terms of similar habitat preferences and similar dietary patterns were prepared. An iterative approach was used to: (a) select candidate assessment species; (b) prescribe data collection needs for characterization of habitat quality; (c) generate spatially explicit descriptions of habitat quality for assessment species; and (d) allocate exposure estimates using habitat quality and distributions of chemical concentration. Information from a previous EcoRA conducted for Kennecott Utah Copper was used to evaluate the efficacy of the approach. Vegetation polygons across the 360-km2 area of the site were generated from infrared aerial photographs. HSI values were calculated for each polygon for selected assessment species. HSI values then were used to modify exposure estimates for selected CoC. Qualitative comparisons of these modified exposure estimates to the findings of the original risk assessment illustrate that the approach would improve the accuracy and relevance of the risk estimates.