The effects of the release of freshwater from the Mississippi river into the Lake Pontchartrain was evaluated. The study determined the delineation of the areal extent of the freshwater plume in the lake, intensively sampled lake and river water and bed sediment to determine the effects on water quality in the lake, and performed a dye study to determine the mixing characteristics of the lake. Water temperature and specific conductance data were used to differentiate between zones of freshwater, mixing, and saltwater. The direction of the freshwater plume seemed to be affected by the wind direction. It was observed that the general direction of the plume was limited to the southwestern part of Lake Pontchartrain.