Appalachian Citizens Enforcement Project

Water Quality 101

Mountaintop removal coal mining adversely affects Appalachian streams by releasing toxic pollution in local streams and filling in entire valleys. By monitoring as volunteers, we can ensure that mine operators are providing accurate reports and can identify where violations may occur.


The ACE Project equips volunteers with water monitoring devices to measure several important indicators of water quality, including conductivity, pH, total dissolved solids, and temperature. Read below to find out what each of these parameters represent, and why they are important.


Conductivity is a measurement of the ability of water to conduct an electrical current. Conductivity is not a pollutant itself, but serves as an indicator of the presence of pollutants. The conductivity of water is affected by the presence of dissolved substances in the water, including salts and heavy metals. Some of these substances are harmful to aquatic life and to humans, especially at high concentrations. Conductivity is measured in microsiemens per centimeter (symbolized as: μS/cm).

The EPA has determined that in central Appalachian streams, values below 300 μs/cm protect aquatic life and values above 500 μS/cm should not be exceeded.

For more information on conductivity in Appalachia, check out Appalachian Mountain Advocate’s article.


pH is the measure of the hydrogen ion activity of the water. A pH value of 7 indicates a neutral water sample, while a pH less than 7 indicates an acidic sample and a pH greater than 7 indicates an alkaline (or basic) sample. The EPA criterion for freshwater pH is 6.0 – 9.0. Changes in pH can have many associated negative effects: more acidic water can increase the release of dissolved metals in the water, many substances become more toxic with changes in pH, and many forms of aquatic life are unable to live in water that varies greatly from a neutral pH. Besides affecting aquatic life, acidic water can damage man-made structures such as bridges, pipes and wells, and may contaminate drinking water supplies.

In Kentucky and Virginia, the discharge of waste water from a mine facility with a pH great than 9.0 or less than 6.0 is a permit limit violation under most circumstances.

Total Dissolved Solids (TDS)

Total dissolved solids (TDS) is the measure of all dissolved substances in a water sample. These substances include anything that can pass through a sieve with a pore size of 2 micrometers (what can be filtered is referred to as total suspended solids). Like conductivity, TDS itself is not necessarily a pollutant, but can indicate the presence of pollutants. Watersheds have naturally occurring dissolved solids, but mine runoff can carry toxic sediments and solids. Increases from a normal stream TDS amounts may indicate the addition of pollutants from a nearby mine. TDS is recorded in milligrams per liter (mg/L).


Water temperature is an important factor because it directly affects aquatic life and the chemical characteristics of a waterway. Changes in temperature can affect the solubility of solids, including heavy metals, and can make some compounds more toxic. Temperature also affects the solubility of gases, such as dissolved oxygen — an important factor in stream suitability for fish and other aquatic life.

Other Parameters

Clean Water Act permits often require mining operations to report levels of metals released into public water. The release of permitted metals is only legal at very low concentrations. Common metals included on permits are manganese and iron, though this does not necessarily mean these are the only substances released from a mining facility. Other substances, such as arsenic, can be detrimental to humans if found in drinking water. Some substances, such as selenium, are not harmful to humans at the levels often found around mines, but can be very toxic to aquatic life.

Testing for these metals requires taking a water sample, which is then sent to a laboratory. This testing is time consuming and expensive, and is therefore not routinely done by our volunteers. We use indicators such as pH, conductivity and TDS to indicate where heavy metal testing should be performed.

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