Linking mountaintop removal mining to water quality for imperiled species using satellite data

Abstract

Environmental laws need sound data to protect species and ecosystems. In 1996, a proliferation of mountaintop removal coal mines in a region home to over 50 federally protected species was approved under the Endangered Species Act. Although this type of mining can degrade terrestrial and aquatic habitats, the available data and tools limited the ability to analyze spatially extensive, aggregate effects of such a program. We used two large, public datasets to evaluate the aggregate effects of mountaintop removal coal mining on water quality over 15 years across Kentucky, Tennessee, Virginia, and West Virginia. We combined an annual map of the extent of surface mines in this region from 1985 to 2015 generated from Landsat satellite imagery with public water quality data collected over the same time period from 4,260 monitoring stations within the same area. We used linear mixed models to estimate the relationship between the proportion of the area draining into a monitoring station that was mined and measures of water quality relevant to standards for sustaining aquatic life. Chronic and acute thresholds for aquatic life were exceeded thousands of times between 1985 and 2015 in streams that were important to the survival and recovery of species on the Endangered Species List. We found that mined area was positively related to increases in conductivity, manganese, sulfate, sulfur, total dissolved solids, total suspended solids, and zinc. The likelihood that chronic thresholds for copper, lead, and zinc were exceeded also increased with mined area. Finally, the proportion of a watershed that was mined was positively related to the likelihood that a waterway would be designated as impaired under the Clean Water Act. Our results demonstrate that mining has downstream effects that must be considered under environmental law. These findings and the public data used in our analyses are pertinent to an upcoming re-evaluation of the effects of current mine permitting regulations to the recovery and survival of federally protected species.