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Insects in Dan River downstream of Feb. 2 coal ash spill appear to be thriving, state tests show
Story Date: 11/25/2014
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Source: NCDENR, 11/24/14
Aquatic insect communities in an area downstream from the Feb. 2 coal ash spill appear to be thriving, according to the results of testing conducted by state environmental officials.
Staff from the N.C. Division of Water Resources on Oct. 28 sampled the Dan River for benthic macroinvertebrates, or small insects and other invertebrate animals that live on or near the bottom of the Dan River. Benthic macroinvertebrate species diversity and population estimates provide an excellent indicator of the overall health of a body of water.
“This is the first testing we have done designed to specifically gauge the ecological health and biodiversity downstream of the spill site after Feb. 2,” said Tom Reeder, director of the N.C. Division of Water Resources. “Since the coal ash spill, we have been concerned about the health of the creatures living in the Dan River. We are pleasantly surprised but still cautiously optimistic about these results and are continuing to conduct several types of tests as part of our ongoing health assessment of the river. Certainly, this is very good news for anyone concerned about the ecological health of the Dan River.”
Using a standard sampling protocol, state scientists collected samples of benthic macroinvertebrate at two locations – one upstream and one downstream of the site of Dan River spill. During the sampling, scientists collect insects and other invertebrates from the river using nets and then record the number and species present in their samples before returning the insects to the river. Scientists can determine much about the health of the river based on the number and type of living species they collect. The populations from the upstream and downstream sites were similar and were considered “Excellent,” which is the highest biological rating available.
Evaluating this animal community’s species diversity and relative pollution tolerance is a long-standing, scientifically defensible measure used to indicate the overall biological condition of a body of water. This method of sampling is routinely used to determine if waters are impaired under the Clean Water Act and also to rate of the quality of the waters.
Testing the health of small aquatic insects is one method to help determine the overall condition of a water body. As part of its ongoing investigation, however, state and federal officials have also continued to test the water quality, fish tissues and the sediment in the river. Water quality monitoring is being conducted every month and state officials are completing a third round of fish tissue samples and expect to publish results of the second round early next year.
The data officials collect about the health of Dan River will be factored into the natural resource damage assessment state and federal officials are conducting.
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