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Effectiveness of EPA conductivity guidance questioned

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A new analysis questions whether the controversial conductivity benchmark the Environmental Protection Agency applied for two years to protect streams below mountaintop mine sites is really the right approach.

This was the news from Mindy Yeager-Armstead, aquatic ecotoxicologist in the Integrated Science and Technology Dept at Marshall University, when she spoke at the West Virginia Water Research Conference hosted Oct. 30-31 in Morgantown by West Virginia University's West Virginia Water Research Institute.

"What's shown in the lab doesn't support what is being said for the field," she said in summary afterward.

Agency battles reviewed

Yeager-Armstead recalled in her talk the often-referenced 2008 paper, "Downstream effects of mountaintop coal mining: comparing biological conditions using family- and genus-level macroinvertebrate bioassessment tools," published in the Journal of the North American Benthological Society, that drew a strong connection between conductivity — saltiness, essentially — and stream-bottom bugs.

To "explore a causal link between mountaintop mining and biological degradation" downstream, EPA scientist and paper author Gregory Pond and his colleagues looked at conductivity and communities of stream-bottom bugs in 10 unmined streams and 27 streams below valley fills.

They also tested sedimentation and riparian habitat against stream health, but the relationships were less clear.

"Our results show that mining activity has had subtle to severe impacts on benthic macroinvertebrate communities and that the biological condition most strongly correlates with a gradient of ionic strength" — in this instance, conductivity — the authors wrote in their abstract.

Fast forward to April 2010: On the strength of these findings and of field tests showing harm to streambed bugs at conductivities as low as 300 microSiemens per cubic centimeter, the EPA set a provisional in-stream level of conductivity for permits of 300 to 500 µS/cm3 below coal mines in Appalachian states.

This "guidance" or "benchmark" was meant to serve as a numerical proxy for the complex and less easily implemented biologic component of state narrative water quality standards — a component represented in West Virginia law by language like "no significant adverse impact" to aquatic ecosystems.

The West Virginia Department of Environmental Protection felt trampled on. The National Mining Association, states and others sued and, in July this year, the agency's guidance was thrown out, freeing up DEP a little to figure out how to implement its narrative criteria.

Useful proxy, or not?

The case challenged the EPA's authority but not the science, leaving the question open: Is conductivity a good proxy for the biologic component of the narrative standards?

As it turns out, coal companies have amassed a dataset that provides another look.

Soon after the Pond paper, Yeager-Armstead said, the EPA began requiring coal companies to conduct toxicity testing of their water discharges.

She and graduate student Leah Creathers, under support from the Appalachian Research Initiative for Environmental Science, or ARIES, obtained data generated by Alpha Natural Resources and Patriot Coal. The data included conductivity and benthic macroinvertebrates sampled at 10 sites per year each, once during high flows and once during low flows.

From the fall of 2008 to the spring of 2012, that has resulted in 129 useful toxicity datapoints and 20 data points with specific ion concentrations.

What emerges from the data, Yeager-Armstead said, is no relationship between conductivity and mortality of the organism Ceriodaphnia dubia, which is used in the laboratory as a surrogate for the streams' benthic macroinvertebrates.

"When you look at those 129 tests and you get up into the conductivity range of 2,000, 2,500 and there's no impairment to the Cerios, that's significant," she said.

Asked how she understands what she characterized as a "discrepancy" between EPA's field results and this laboratory data, she said, "I'm scratching my head."

Although C. dubia is not itself found in Appalachian streams, it has been found to be a good surrogate for what does live there, she said.

The tests were ordered by the EPA, were conducted at sites approved by the EPA and were performed using EPA protocol.

Back to the actual environment

In the end, these technical matters relate directly to policy and to the state's economic and environmental health.

"That's why it's bothersome to me," Yeager-Armstead said. "If I see the conductivities not causing toxicity to the Cerio and so much energy being focused on the conductivity in the streams, I think we might be missing something else."

If land is disturbed, whether it's to build a subdivision or a coal mine or a golf course, conductivity will go up, but so will sediment, she said.

There's also light penetration from loss of tree cover and temperature fluctuations from the higher winds that result. There's runoff. And there's a change in the algae that grows in response to the different light.

"Conductivity is an indicator of all these other changes, any one of which might affect the bugs," she said. "But if we say we're going to remove all the ions from the water but we still have an open canopy with sediment changes and more light, we might have a multimillion-dollar treatment facility and still not have the bugs. That's why we have to incorporate everything that's going on in the watershed."

What comes next

That is, in a sense, just what DEP is doing now: working on more specific and sophisticated language for how to implement the narrative criteria, possibly for introduction in the state Legislature in 2014, DEP Secretary Randy Huffman has said.

Creathers is preparing the analysis for submission to a scholarly journal.

And Yeager-Armstead said she would like to see all of the science inform good policy.

"We know you can run conductivity high enough to cause stress — that's why we have saltwater fish and freshwater fish," she said. "But instead of just using 300 to 500, let's use the data to say ‘Here's the level that's protective.'"

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