Print PageMountaintop mining is now the dominant driver of land-use change in the Central Appalachians. Over the last decade, an estimated 2000km of streams in this region have been buried beneath the excess rock waste generated from surface coal mining. In addition to the streams permanently lost through valley filling, many more kilometers of streams downslope of mining activities are impacted. Field studies have demonstrated higher flows and chemical concentrations, as well as losses of biodiversity, at sites with upstream surface mining operations. But how much surface mining can occur before there are significant changes in the physical and biotic structure of downstream ecosystems? For a 14 county region in southern West Virginia we use new remote sensing analyses together with state-maintained streamwater chemistry and macroinvertebrate sampling data for 283 stream reaches to estimate the areal extent of mining that can occur in a watershed before significant ecological impacts are observed in draining streams.
Results/Conclusions
We demonstrate that changes in streamwater conductivity were strongly positively correlated with the extent of watershed surface mining and negatively associated with development. We detected a significant threshold response in invertebrate community composition to altered ionic strength, with many sensitive taxa declining precipitously in abundance above a conductivity of 277μS cm-1. Our analysis is the first to demonstrate that the rapid increase in mining activity within regional headwaters is degrading water quality and freshwater ecosystems at very low mining intensities and over very large geographic scales. We find that stream water quality and benthic communities are significantly altered when as little as ~3% of the upstream watershed is converted to surface mining operations. We are now expanding the geographic extent of our analysis to include regions of Kentucky, Tennessee, and Virginia, as well as to assess changes in diatom and fish community compositions.
