Researchers say large amounts of minerals leach into streams from valley fills that have been filled with rock blasted from the mountaintops and ridges above. Sara Peach of Chemical and Engineering News reports that researchers have previously documented water pollution near individual mines, but have not been able to detect how far the pollution traveled, study author Emily Bernhardt said. Her study found harm to aquatic life in more than 1,700 miles of streams in southern West Virginia.
Bernhardt and her co-authors mapped chemical and biological data from 223 streams sampled by the state Department of Environmental Protection between 1997 and 2007, and found that salinity and mineral levels in the region's streams increased with the total area of mountaintop mines. They also discovered that as the number of mines increased, fewer sensitive insect species were found downstream. Substantial declines in insect populations were seen with just 1 percent of upstream land mined. In areas where 5 percent of upstream land has been mined, so many species have disappeared that the streams would qualify as biologically impaired, a designation that would place the streams on a list of waterways that states have to rehabilitate. (Read more)