Downstream Effects of Mountaintop Mining: Context Matters

Mountaintop mining in southern West Virginia results in significant impacts to downstream ecosystems.  Research documenting complex relationships among multiple landscape factors suggests equivalent levels of mine development can have different consequences given pre-existing landscape characteristics.  Through a watershed-scale assessment of the Coal River (south-central West Virginia), the objectives of this study were to:  1) quantify individual effects of dominant stressors, including identification of impairment thresholds, 2) quantify the combined effects of multiple stressors (i.e., surface mining, deep mining, and residential development), and 3) predict the extent to which landscape context affects the outcome of proposed mining projects.  Both surface mining and residential development were significantly correlated with altered in-stream conditions.  Biological impairment occurred at 21.4% mining and 8.1structures/km².  Benchmarks for specific conductance and Selenium were crossed at 17.8% and 30.5% mining, respectively.  The combined effects of surface mining, deep mining, and residential development were additive for physical habitat and water chemistry.  However, we found evidence of an interaction of deep mining and residential development on community structure.  Impairment was predicted at much lower levels of future surface mining when pre-existing development and deep mining were present.  Regulatory decisions regarding future mine permitting and mitigation must account for non-mining related impacts.