Mountain top removal, i.e., stripping off the tops of mountains to mine coal, is not an issue in Illinois, but I grew up in Kentucky and its been a big controversy there and other Appalachian states for a long time. Its hard to believe that there was ever any doubt that mountain top removal polluted surface waters, but thats what some mining industry groups would have us believe. Recent studies put to bed those doubts.

As reported in a recent issue of Nature, in August researchers presented results at the Ecological Society of America conference in Pittsburgh on the effects of mountain top removal in West Virginia. In this type of mining, the overburden is blasted away and pushed down into the mountain valleys, typically burying streams. Some of the potential contaminants that can leach into streams include selenium, heavy metals, and sulfate. In the studies reported here, the researchers focused on total dissolved solids levels, as measured by electrical conductivity. Currently, EPA recommends that mining activities shouldn’t increase stream water conductivity to greater than 500 microsiemens per centimeter (µS/cm). In West Virginia watersheds where significant mining has occurred, conductivity levels were almost always greater than 500 µS/cm. Even in areas with low levels of mining (no more than 2.5% of the watershed mined), about 30% of streams still had conductivity levels greater than 500 µS/cm. Sharp declines in stream invertebrate populations were observed in streams with increased conductivity.

Mountain top removal advocates have claimed that increased conductivity levels could be due to increased urbanization or other land use changes. However, in this study it was shown that conductivity levels were generally much higher in streams in mining areas when compared to urbanized streams in West Virginia.

Coal is the world’s most reliable and cheapest energy source, and we’ll likely still be using it centuries from now. But there are costs associated with its extraction and consumption, and not just the carbon dioxide emissions linked to climate change. If you’re interested in reading more about the environmental and social costs of mountain top removal, here’s an article by Erik Reece. Reece also wrote an excellent book I read a few years back that I recommend.