Specific Conductivity 

• The term total dissolved solids refers to any material that is suspended (or floating) in the water column
• Specific conductivity is a measure of how good water is at conducting electricity
• The amounts and types of dissolved particles in the water directly influence specific conductivity
• Specific conductivity is measured using specialized probes that measure how well an electrical current travels between them.

 Once scientists have measured the turbidity (or water clarity) of the water, it is important to study what exactly is in the water.  There are many types of minerals or organic material that may be present in the water; these are referred to as the total dissolved solids (TDS).  There is specific instrument that measures the concentration (or amount in a certain volume) of TDS in the water.  This instrument measures how well an electrical current passes through the water by passing an electrical current between two probes.  This is known as specific conductivity.  The higher the level of TDS, the better the water will be at conducing electricity.  If the water is pure and does not contain many dissolved particles then it will be a poor conductor of electricity.  One of the most common minerals found in water is salt.  The salinity of the ocean is about 35 parts per thousand, that means if you took a sample of ocean water and classified every part of it, 35% of the content would be salt.  Most of the salt and other dissolved solids found in a lake are brought there by rivers or tributaries. Not all of the salts that you find in the lake are naturally there; some are anthropogenic (human impact on nature) such as road salt and agricultural run-off.  The level of salt in the water determines what types of organisms can live in the lake.  Saltwater fish have specific adaptations to cope with the salty water; freshwater fish wouldn’t be able to survive in the same habitat because they lack those specialized features.