More Science Reveals the Harmful Legacy of Surface Mining for Coal

It’s looking like the science is telling us what we have pretty much figured all along, that surface mine reclamation is only a half measure at best. In a recently published scientific paper, “Exploring the legacy effects of surface coal mining on stream chemistry,” scientists studied 30 surface mines in a southern Ohio watershed. The study found that, though reclamation efforts to reduce acid mine runoff seem to be successful, the conductivity of stream water continued to remain high, with some concentrations high enough to impair the biota of many streams. Levels of aluminum in the streams remained high as well.

            The study examined stream waters in the Raccoon Creek watershed, which flows directly into the Ohio River. The study found that, when it came to conductivity, reclamation efforts had little effect. The greatest predictor of high conductivity in a subwatershed was the percentage of the area of that watershed that had been surface mined. The greater the percentage of land that had been mined, the higher the conductivity.

The Raccoon Creek watershed shown in blue, the watershed examined in this study map from  epa.state.oh.us

Conductivity is the measure of water’s ability to pass a current of electricity. High conductivity of water is usually an indication of the presence of inorganic dissolved solids, such as chlorides, nitrates, sulfates, and phosphates. High conductivity can also indicate the presence of sodium, magnesium, calcium, iron, and aluminum. In streams conductivity is measured in microsiemens per cubic centimeter (uS/cm2). Streams that have a good mix of native fish have conductivity ranging from 150 and 500 uS/cm2. Ecological impairment and decreased biological diversity are found in streams with conductivity exceeding 500 uS/cm2. Eight of the 30 sites in the study had conductivity levels exceeding the 500 uS/cm2 threshold.

            Aluminum is a common trace element in coal. It can be disruptive to streams and lakes and, as it has been associated with dementia and Alzheimer’s disease, is not desired at high levels for drinking water. The Ohio Environmental Protection Agency limits the amount of aluminum in drinking water to 0.20 milligrams per liter. This limit was exceeded at 20 of the 30 sites. Moreover, aluminum toxicity to fish has been observed as low as 0.10 milligrams per liter.

            Reclamation, to me, has always seemed like a Humpty Dumpty scenario. Take apart a hillside or a mountain, and all the king’s horses and all the king’s men could never replace the land, streams, and ecosystems as they once were. Common sense tells us this, now the science is confirming it.