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EPA Science on Mountaintop Mining

Researchers release two scientific reports to support Agency’s new guidance for mountaintop mining.

A mountain top mine

“The people of Appalachia shouldn’t have to choose between a clean, healthy environment in which to raise their families and the jobs they need to support them.”

EPA Administrator Lisa P. Jackson made the above remarks when she announced a set of actions the Agency was taking to further clarify and strengthen environmental permitting requirements for Appalachian mountaintop removal and other surface coal mining projects. EPA issues permits for such actions in coordination with other federal and state regulatory agencies, including the Army Corps of Engineers.

“The underpinning for the guidance is a growing body of science demonstrating that degradation of ecosystems in Appalachian states is being caused by mountaintop mining,” explained Administrator Jackson.

The emerging body of science includes important research and analysis conducted by EPA scientists. Two new major EPA studies—The Effects of Mountaintop Mines and Valley Fills on Aquatic Ecosystems of the Central Appalachian Coalfields, and A Field-based Aquatic Life Benchmark for Conductivity in Central Appalachian Streams—were released in conjunction with the new guidance.

The two reports were published for public comment and submitted for peer review by the EPA Science Advisory Board.

Mountaintop mining is a form of surface coal mining in which the natural vegetation from the upper topography of a mountain is removed, and then heavy equipment and explosives are used to level the upper sections to expose seams of coal. 

As the tops of mountains are removed, what was once the underlying earth and rock becomes valley fill, filling in adjacent valleys and burying nearby streams.  Geographers estimate that almost 2,000 miles of small, upper level Appalachian “headwater” streams have been buried by mountaintop coal mining.

A number of ecological concerns surround mountaintop mining and valley fill. Much of that concern centers on water quality. Burial of headwater streams causes permanent loss of aquatic ecosystems that play critical roles in ecological processes, such as the cycling and flow of nutrients between the environment and living organisms and the stability of the food web. These small Appalachian streams also support abundant and diverse types of aquatic organisms that are unique to the area.

In addition, the removal of natural vegetation and physical changes to the soil and topography greatly impact water runoff, flow, and quality. Water that flows over and through valleys with valley fill is known to contain greatly elevated concentrations of chemical ions (salts), as well as other substances. A growing body of scientific literature, including studies conducted by EPA researchers, shows significant damage to local steams that are polluted with the mining runoff from mountaintop mining.

The new guidelines clarify actions that EPA will take to protect Appalachian ecosystems as the Agency follows its mandate to uphold and enforce the Clean Water Act. The two new science reports were produced to provide the Agency with the best available science for crafting the guidelines.

The Effects of Mountaintop Mines and Valley Fills on Aquatic Ecosystems of the Central Appalachian Coalfields provides a state-of-the-science assessment on the ecological impacts of mountaintop mining and valley fill operations. EPA researchers identified and reviewed some 277 citations, including books, conference proceedings, journal articles, reports, theses/dissertations and other sources to present a single-volume assessment of the latest science available on the aquatic impacts associated with mountaintop mining.

The analysis identifies five key impacts directly related to mountaintop mining and valley fill:

  1. springs, intermittent streams, and small perennial streams are permanently lost with the removal of the mountaintop and from burial under fill,
  2. concentrations of major chemical ions are persistently elevated downstream,
  3. degraded water quality reaches levels that are acutely lethal to standard laboratory test organisms,
  4. selenium concentrations are elevated, reaching concentrations that have caused toxic effects in fish and birds and
  5. macroinvertebrate and fish communities are consistently and significantly degraded.

The second report, A Field-based Aquatic Life Benchmark for Conductivity in Central Appalachian Streams, provides the scientific basis for using a field-data-derived, conductivity-based measurement as the benchmark for water quality in order to protect aquatic organisms living in Appalachian surface waters.
Conductivity is a measure of the level of salinity (salt) in the water. Because mountaintop mining operations can raise the salinity levels of nearby streams, measuring it provides an indication of those operations’ impacts on water quality. EPA scientists conducted more than 2,000 field samples to derive a conductivity benchmark that protects 95% of the genera (sets of similar and closely related species) of aquatic organisms living in streams in central Appalachia.

Key findings of the report include:

  • Concentrations of salts as measured by conductivity are, on average, 10 times higher downstream of mountaintop mines and valley fills than in un-mined watersheds. 
  • The increased levels of salts disrupt the life cycle of freshwater aquatic organisms, and some cannot live in these waters.  Water with high salt concentrations downstream of mountaintop mines and valley fills is toxic to stream organisms. 
  • There are also higher levels of the chemical selenium downstream of mining sites.  Selenium exceeded the level established by EPA to protect aquatic life at more than half of the sites surveyed downstream of mountaintop mines and valley fills.
  • By plotting the conductivity levels at which organisms are no longer observed in streams, we can determine a level of conductivity that results in their loss.  
  • EPA identified a conductivity benchmark (300 microSiemens per centimeter) that protects 95% of the genera of aquatic organisms living in streams in central Appalachia.

The two reports were produced to provide the best available science on the environmental impact of mountaintop mining. “We will continue to work with all stakeholders to find a way forward that follows the science and the law,” said Administrator Jackson.

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