Conductivity tells us how well the water sample can carry an electric current.  Conductivity is influenced by the amount of negatively charged ions (such as phosphate and nitrate) and positively charged ions (such as sodium and calcium) found in the water. 

Why We Test Conductivity

While a high or low conductivity measurement cannot identify which ions are out of balance, it can indicate the need for more specific water quality tests to pin-point the problem. Arsenic, for example is a human carcinogen according to the International Agency for Research on cancer. Conductivity readings can also indicate environmental problems such excessive salts that may be harmful to plants, causing=using wilting, root death, and leaf drop.

Too Few ions may indicate high levels of oils or hydrocarbons that are not healthy for aquatic organisms or humans that come in contact with them.

Sources

Conductivity can be influenced by the geology of the stream and surrounding watershed, temperature, and industrial and wastewater discharges. 

Wadable Stream Guidelines

• Values between 50 and 500 umhos/com are normal
• Values below 10 are undesirable

Conductivity usually ranges from 50 -1500 umhos/cm, but is best for plant and animal life between 150-500 umhos/cm.

How Do We Test For Conductivity:

Pdf of sampling technique used by Stream Team.