ET-4F1 (2/17/05 version)
Chemical Integrity: Abandoned Mine Drainage (AMD)

Why is this a Water Quality Problem?


Prior to 1977, the laws governing the environmental impacts of coal mining operations were less stringent. Therefore, it was a common practice to simply abandon mining operations following the exhaustion of the coal reserve. Consequently, abandoned mine drainage (AMD) is a key water pollution problem in the coal fields of Appalachia. AMD is most often characterized by one or more of the following:

  • Low pH (high acidity) known as acid mine drainage;
  • High metal concentrations (most commonly iron, aluminum, and manganese);
  • Elevated sulfate levels;
  • Excessive suspended solids and/or siltation.

Specifically, highly acidic or acid mine drainage is the most common and severe water quality impact. At sufficiently low pH, a stream is effectively dead. Impacts include toxicity to fish and aquatic insects, absence of or degraded habitat (particularly primary headwater habitat), stunted plant growth, disintegration of concrete and metal structures, increasing water treatment costs, and stream banks and beds discolored a bright, rusty orange.

Summary, Water Quality Status

  • 79 of the 331 Watershed Assessment Units (WAUs) in Ohio are located in the southeastern Ohio coal-bearing region;
  • Per the Ohio EPA 2002 Integrated Water Quality Report, of the 79 WAUs, 60 are known to be polluted (PDF 819kb) by varying levels of mine drainage; The 2002 Report included all documented surface mining sources of water quality impairment, segregated by magnitude (relative contribution) of mining to the impairment (i.e. - high, moderate, slight, or threat)
  • The 2004 Integrated Water Quality Report lists 21 WAUs where the major source of impairment is surface mining, subsurface mining, acid mine drainage, and/or mine tailings; the change in number of WAUs impaired by mining does not reflect a sudden improvement in water quality, but rather focuses on those watersheds where the contribution of mining to impairment is "high"
  • Of the 21 WAUs, impairment in 6 is caused by coal mining related siltation and sedimentation;
  • Of the 21 WAUs, impairment in15 is caused by coal mining related pH, metals, and siltation;
  • Of the 79 southeastern coal bearing WAUs, the 2004 Integrated Water Quality Report states that 43 are in need of more study to determine levels and causes of impairment.
  • Maps summarizing percentage attainment and showing unassessed watersheds are available for WAUs and Large River Assessment Units.

Priority Areas

Restoration efforts are focused on the southeastern coal-bearing region of Ohio and within this region are prioritized based on:

  • a) streams in "Qualified Hydrologic Units" (QHU = a watershed with an approved Abandoned Mine Drainage Abatement and Treatment- AMDAT - Plan); AMDATs (PDF 389kb)) contain pH, metals and acidity loading targets specific to the particular watershed addressed in the plan;
  • b) streams where mine drainage pollution is a primary limiting factor in aquatic life use (as determined by EPA 305(b) assessments, where the mining related impairment is ranked as Medium to High (PDF 819kb)); and
  • c) streams where pollution from mining has caused significant impairment to a unique aquatic community, sport fishery, public water supply, or recreational use and the ODNR, Division of Mineral Resources Management (DMRM) has received a request for assistance to address the impairment.