- Surveys of flora and fauna were conducted in riparian areas of six streams in the general vicinity of the Iron Mountain mine near Redding, California. The surveys were intended to provide part of the information needed for a natural resource damage assessment (NRDA), should such an assessment be desired at some point.
For both birds and plants, the field data clearly show differences between the presumptively contaminated vs. uncontaminated areas. Most of the differences were statistically significant. Although field data also show some statistically significant differences in bird and plant habitat structure between presumptively contaminated vs. uncontaminated areas, it cannot be assumed that those differences are the only cause of the differences in bird and plant communities among streams. Strong circumstantial evidence points to contamination status, in addition to habitat, as a significant factor influencing the bird and plant communities.
Future efforts should focus first on sampling soils and possibly other media at each of the bird and plant survey points, to determine relative degree of contamination, and to then compare that ranking to the presumptive categories assigned those points during this study. Consideration should also be given to confirming results by employing additional protocols specifically mentioned for NRDA studies, such as brain cholinesterase enzyme activity (ChE) determinations and direct measurements of reduced avian reproduction. Finally, the specific pathways by which resources have likely been damaged should be investigated, for example, by monitoring avian feeding habits at nests in relation to invertebrate availability.