What is acid
Mine drainage is the result of the exposure of pyrite to oxygen and water. Pyrite is found in association with coal deposits, and past coal mining caused this mineral to weather, releasing iron and acidity to the waters.
Once these waters reach the surface, iron oxidizes and precipitates iron hydroxide (yellow boy) on the stream bottoms, choking out most aquatic life. For a brief chemistry lesson, see AMD Primer. For pictures of untreated mine drainage in the Shamokin Creek watershed, click here.
Coal mines now operate under much more strict regulations than in the past. Very little mine drainage escapes from current mines. The mine drainage nearby is almost exclusively from abandoned mines, so no responsible parties can be found to clean up the waters. This leaves the tasks to governments and citizens groups like the SCRA. Western Pennsylvania has aggressively begun to reduce mine drainage from abandoned mines. Now it is our turn!