April 26, 2011

Valley Fill Study Refutes EPA Science

EPA’s contention that unique insect populations in headwater streams are endangered by valley filling practiced by mountaintop mining operations in Appalachia was challenged in a scientific study sponsored by the National Mining Association (NMA).

In April 2010, EPA issued guidance to ensure that permits for mountaintop mining operations complied with water quality standards. Specifically, the Agency set a conductivity limit of 500 microSiemens applicable to CWA Section 402 permits issued by the Army Corps of Engineers. Conductivity is a measure of the capacity of water to conduct electricity. It is typically measured by the presence of dissolved particles that carry an electrical charge. The mining industry said the limit will make it extremely difficult to conduct new mining operations in Appalachia.

Before setting the limit, the Agency investigated the effect of valley filling on aquatic life as represented by mayfly populations, which, the Agency said, are widespread in the mountaintop coal mining region and constitute a unique and irreplaceable resource.

NMA retained GEI Consultants to investigate EPA’s science. The company looked at 12 headwater streams in the coal mining region of southern West Virginia.

GEI’s key finding is that the streams do not constitute an essential habitat without which the mayfly population cannot survive. Instead, states GEI, all streams investigated are essentially the same, and mayflies populate them opportunistically, that is, they simply breed in whatever stream is available. Hence, “loss of a limited number of individual streams should not jeopardize the overall regional diversity that potentially colonizes these extreme headwater reaches of these southern West Virginia streams,” states GEI.

GEI also states that mayflies are not as dominant in numbers as EPA claims, comprising less than 10 percent of the community at most study sites and completely absent from one-fourth of the streams studied. Therefore, the validity of EPA’s reliance on the mayfly as an indicator of biodiversity is questionable, asserts GEI.

EPA did not immediately respond to the study, but the Agency may need to do so to continue to claim that its conductivity limit is supported by the best science.

The GEI study is available at http://www.nma.org.