Specific conductance is a standard meas. for water quality (in environmental work). The sample measured was unfiltered and the unit of measure for specific conductance is siemens, micro is just very little (like kilograms, grams, milligrams, micrograms.

Specific conductance is a measure of the ability of water to conduct an electrical current. It is highly dependent on the amount of dissolved solids (such as salt) in the water. Pure water, such as distilled water, will have a very low specific conductance, and sea water will have a high specific conductance. Rainwater often dissolves airborne gasses and airborne dust while it is in the air, and thus often has a higher specific conductance than distilled water. Specific conductance is an important water-quality measurement because it gives a good idea of the amount of dissolved material in the water.

The data that you are looking at is derrived where I work. I work on the CRMS project, and we compile the specific conductance and salinity data for USGS. Specific conductance is calculated from water temperature and salinity in a certain area. The higher the salt content, the higher the spedcific conductance. Microsiemens per centimeter is what it is measured in.