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
[From Press Release] 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:
- springs, intermittent streams, and small perennial streams are permanently lost with the removal of the mountaintop and from burial under fill,
- concentrations of major chemical ions are persistently elevated downstream,
- degraded water quality reaches levels that are acutely lethal to standard laboratory test organisms,
- selenium concentrations are elevated, reaching concentrations that have caused toxic effects in fish and birds and
- 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. [H/T: Greenwire, sub. req'd]