Conductivity
(Total Dissolved Solids)

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.  Conductivity can be influenced by the geology of the stream and surrounding watershed, temperature, and industrial and wastewater discharges.  Conductivity usually ranges from 50 -1500 umhos/cm, but is best for plant and animal life between 150-500 umhos/cm.

Dissolved solids are tiny particles containing constituants like iron, calcium, nitrate, and phosphate that are dissolved in the water.  Total suspended solids can also be measured, which is the concentration of suspended (floating) particles in water.  The concentration of dissolved solids is very important to the well-being of aquatic life; too much or too little can affect the ability of aquatic life to maintain a position in the water column.  High levels of TDS can cause water temperature to rise and make habitat unsuitable for plants and/or animals.  TDS can be influenced by fertilizer, wastewater and industrial discharges, sewage, erosion, and runoff from roads.