It is important to note that chemicals in highway runoff are not the major sources of chloride contamination of waters. Sewage discharges and runoff from industrial waste and agricultural products also contain high concentrations of chloride that may affect receiving waters as well. Rain and snow may deposit as much as 35 to 40 pounds of chloride per acre annually even without the presence of de-icing chemicals. Areas that are geographically located along coastal waters also experience high chloride concentrations since chloride occurs naturally in sea water, natural brines and water which passes through salt-bearing strata.