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Button that takes you to the Acid Mine Drainage page. Button that takes you to the Chemistry page. Button that takes you to the Dissolved Oxygen page. Button that takes you to the Alkalinity page. Button that takes you to the Conductivity page. Button that takes you to the pH page. Button that takes you to the History of Coal Mining page. Image that says Acid Mine Drainage: Hardness.
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Button that takes you to the Dredging page.		 Acid Mine Drainage: Hardness
 Image of two people looking at some baserock. This image links to a more detailed image.Water hardness is the total concentration of cations, specifically calcium (Ca2+), magnesium (Mg2+), iron (Fe2+) and manganese (Mn2+) in water. Photo: Courtesy of Kenneth E. Rastall

A stream's hardness reflects the geology of the catchment area and sometimes provides a measure of the influence of human activity in a watershed. For instance, acid mine drainage often releases iron (Fe2+) into a stream, resulting in extraordinarily high hardness readings. For this reason, hardness is a useful water quality indicator. For the most part, however, hardness is a measure of the calcium and magnesium that enters the stream through the weathering of rock.

In the Wheeling Creek watershed, the bedrock is mostly limestone. Limestone is calcium carbonate, or CaCO3. When limestone weathers, it dissolves into calcium (Ca2+) and carbonate (CO32-). Calcium is an important nutrient used by plants and animals as it moves downstream. Carbonate enters the carbonate buffering system described under alkalinity.

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