Salinity

• According to the South Carolina Department of Natural Resources (SCDNR), salinity is defined as the amount of salts in grams dissolved in one kilogram of saltwater, so 35 grams of dissolved salt in one kilogram of water would be 35 ppt or 35 parts per thousand. The SCDNR lists the salinity of saltwater at around 35 ppt and freshwater at less than .05 ppt.
  
  

Sources

• There are many different sources that may allow salt to enter lakes and other bodies of water. Langston University claims that such causes of salts may be; septic systems, livestock salt blocks, highway salting and even abandoned oilfields. Salt introduced into the water is usually in highest concentrations during flooding or heavy rainfall.
  
  

Tolerance

• The University of Massachusetts recently introduced a study of water quality factors, including salt. In this study it was determined that a salinity between 0.5 to1.0 ppt is preferred for freshwater fish. Salinity rising higher than 1 ppt will can cause fish to die, as they are unable to process the additional salt.