A quasi-synoptic survey of tidally induced salinity changes off the Georgia coast was performed by using a L band microwave radiometer onboard a NASA aircraft. Salinity maps were obtained for ebb and flood condition in order to define the salinity distribution near rivers and sounds and major changes that occur from ebb flow to flood flow. The Savannah River plume dominated the salinity regime and extended out from the Savannah River mouth about 12 km during ebb tidal conditions. The plume merged into a band of low salinity water extending along the Georgia-South Carolina coast which was produced by the many river sources of freshwater entering the coastal waters. The changes in salinity observed offshore of the river plume area were consistent with estimates of the changes that would occur over a typical tidal excursion perpendicular to the observed gradient.