In a finding fatal to the EPA’s regulatory assumptions, “These conclusions call into question the need for a [conductivity] limit and suggest that a singular focus on mayflies is not necessarily the best way to evaluate the ecological health of Central Appalachian watersheds,” concluded the report by GEI Consultants.
The study of a dozen headwater streams, prepared by GEI Consultants for the National Mining Association (NMA), concluded that specific water quality characteristics of this ecosystem correspond only weakly to invertebrate populations and do not determine the specific mixture of aquatic bugs found in upland streams as the EPA assumes. Moreover, the mayfly the EPA proposes as an indicator species for determining its controversial “conductivity” standard is not dominant and sometimes not even present in this ecosystem.
The study, Variability of Benthic Invertebrate Communities of Headwater Streams in Southern West Virginia, provides no evidence to support the EPA’s conclusion that discharges from coal mining operations into the extreme upper reaches of streams cannot be permitted under the Clean Water Act.
“These scientific findings reinforce common sense judgments about the weak rationale for the entire regulatory edifice the EPA has used against coal mining in Appalachia and should certainly raise new doubts about the wisdom of pursuing this course,” said NMA Vice President for Environmental Affairs Karen Bennett.
Debugging the EPA’s Stance Against Mountaintop Mining
Surface coal mining operations in steep sloped terrain must place excess spoil material in valley fills located in headwater stream channels. Discharges of spoil material to headwater streams are allowed under the Clean Water Act (CWA), so long as the activity takes place under permits authorized by the U.S. Army Corps of Engineers.
The EPA maintains these headwater streams represent a wide variety of habitats that host diverse aquatic “bug” communities, particularly mayflies, and concludes they constitute “a unique and irreplaceable resource.” Consequently, the EPA claims impacts to these headwater streams cannot be mitigated and discharges to such streams should be prohibited under the CWA.
For the EPA’s assertions to be true, each of these streams’ specific habitat and water quality characteristics would necessarily and directly determine what specific mixture of invertebrates (aquatic bugs), or invertebrate community, can reside in each stream that correspond to each of those specific conditions.
The NMA Headwaters Streams Study, conducted in 12 headwater streams in the coal mining region of southern West Virginia by GEI Consultants was designed to test these assumptions.
Contrary to the EPA’s assertions, the study concludes that while headwater streams exhibit less than 50% similarity in the composition of their invertebrate communities, they are likely assembled opportunistically from commonly encountered species with broad habitat requirements. Instream habitat and water chemistry characteristics showed weak relationships to invertebrate populations. And, contrary to EPA suggestions that 25%-50% of the total invertebrate abundance in central Appalachian headwater streams should be comprised of mayflies, mayflies were not dominant and sometimes not even present in these headwaters streams. The EPA’s proposed “core community” of mayfly populations does not exist in these streams as the EPA suggests is to be expected.
These findings have important implications. First, they undermine one of the key foundations for the EPA’s objection to the issuance of CWA Section 404 and 402 permits for coal mining operations in steep sloped terrain. This objection is that loss of even a small number of headwaters communities would be detrimental to regional biodiversity; the results of the GEI report contradict this assertion. Second, they cast doubt on the validity of the EPA’s newly developed benchmark limit for conductivity that is almost exclusively justified on the basis of protection of mayfly populations in Appalachian headwater streams. These conclusions call into question the need for such a limit and suggest a singular focus on mayflies is not necessarily the best way to evaluate the ecological health of Central Appalachian watersheds.
The study also demonstrates that:
• Diverse benthic invertebrate communities exist in extreme headwater streams. While individual communities differed from each other to some extent, these streams are not unique in the levels of diversity and variability among macroinvertebrate communities;
• Mayflies are not as dominant in these headwaters streams as has been postulated by EPA studies conducted in the region;
• Mayflies comprised less than 10% of the community at most study sties and were completely absent from one-fourth of the steams studied. The EPA proposed core mayfly community does not occur in the headwater communities studied and the expectation of high proportions of the community being mayflies is an erroneous assumption;
• Instead of being related to site-specific habitat or water chemistry differences, headwater streams communities appear to colonize steams opportunistically, and not deterministically as the EPA asserts. In other words, headwaters streams are being colonized from a broad range of organisms with broad habitat requirements that are commonly encountered in this region;
• Since the macroinvertebrates from a larger regional pool of species appear to colonize these stream reaches opportunistically, loss of a limited number of individual streams should not jeopardize the overall biodiversity in the extreme headwaters streams of the region.
For a copy of the report by GEI consultants, go to: http://www.nma.org/pdf/tmp/033011_GEI_final_report.pdf.