Development of the waterfront lands of southeast Dade County depends upon the construction of sea walls (bulkheads) and filling of the lowlying land. To assist Dade County officials in planning the devleopment of the area, an investigation was made to determine the elevation of mean high water and tidal patterns in the south Biscayne Bay area. The results of the investigation area based on records collection from ten tide gages during the period July 1, 1967 through June 30, 1968. Prior records from most of the gages were available for coorelation. The elevation of mean high water was 1.5 feet in central Biscayne Bay and 0.9 foot in the lower bays. The mean tidal range was 2.0 feet in Central Biscayne Bay and 0.5 foot in the lower bays. The differnece between mean half tide and mean water level was found to be negligible at all stations. The time lag for high and low tides, reffered to Miami Beach, as approximately one hour in Biscayne Bay at Manatee Bay.