What is Conductivity?

Conductivity is the measurement of how well the water conducts electricity through its content of ions and is measured in standard unit microSiemens per centimeter (µS/cm). Naturally occurring ions include calcium and magnesium, but urban streams and rivers are also subject to pollution from sewage overflows, industrial discharges, and stormwater runoff containing nitrate, phosphate, chloride, salt, and metals ions.

Why is Conductivity important?

Conductivity can be an indicator of an unnatural or harmful imbalance of the ion content of the water. Low levels of Conductivity may indicate a lack of elements essential for aquatic life, such as calcium and magnesium, due to pollution discharges containing noncharged ions, such as oil and phenols. High levels of Conductivity may indicate harmful levels of toxic chloride, salt and metals ions from pollution discharges from sewage, stormwater, and industrial sources.

How do we measure Conductivity?

Conductivity is measured with a probe that is lowered by staff or volunteers into the water at each station location. Conductivity readings are recorded half-way between the water’s surface and the river bottom. The State of Maryland has not established an assessment threshold for Conductivity.