A Monitor's Guide to Water Quality


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Conductivity in lakes and streams generally ranges between 0 to 200 µS/cm, while in major rivers conductivity may be as high as 1000 µS/cm. Very high conductivity (1000-10,000 µS/cm) is an indicator of saline (salty) conditions. 

Each lake and stream tends to have a relatively constant range of conductivity. This can be valuable information to have as a baseline for comparison. Significant changes in conductivity outside normal seasonal ranges could indicate a source of pollution.

For example, sewage entering the water would raise conductivity whereas an oil spill may lower conductivity. In urban areas, winter road salt can be a major source of increased salts in the water, especially during spring melt.

Related to conductivity: total dissolved solids (TDS) and, to a lesser extent, hardness

Conductivity is influenced by:  concentrations of dissolved ions (salts), water temperature