St. John the Baptist Parish
|Type||it is a round-shaped, shallow, Brackish water tidal estuarine system|
|Basin countries||United States|
|Surface area||240km2 or 92.66mi2|
|Average depth||3.0 meters or 9.843ft2|
Lake Maurepas was named for Jean-Frédéric Phélypeaux, Count of Maurepas, an eighteenth-century French statesman, chief adviser to King Louis XVI. Maurepas was the son of Louis Phélypeaux, comte de Pontchartrain for whom Lake Pontchartrain is named.
Lake Maurepas is a round-shaped, shallow, brackish tidal estuarine system. It is approximately 240 km2. in area and has a mean depth of about 3.0 meters. The lake receives freshwater input through four river systems: Blind River, Amite River, Tickfaw River, and the Natalbany River. The average freshwater input to Lake Maurepas from these rivers and other minor terrestrial sources is <3,400 cubic feet per second (CWPPRA Environmental Workgroup, 2001). At the northeast, Lake Maurepas is connected to Lake Pontchartrain by two passes: Pass Manchac and North Pass. The land between these two passes forms Jones Island and the passes converge on the eastern side of the island into one unified Manchac Pass. Tidal exchange with Lake Pontchartrain through Pass Manchac is a more significant influence on Lake Maurepas’s volumetric and elevation characteristics than tributary freshwater discharge. The mean astronomical tide in Lake Maurepas is approximately 0.15 m (0.5 ft); however, greater tidal amplitudes are associated with meteorological events (i.e., winds) that influence both Lake Pontchartrain and Lake Maurepas. This results in interesting patterns of tidal exchange and, presumably, in situ mixing on weekly and fortnightly time scales. The lake’s salinity is directly influenced by exchange with Lake Pontchartrain. Salinities in Lake Maurepas have been observed to range between 0 and 3 parts per thousand (Day et al., 2004). Typically, salinities are higher along the eastern shore, near Pass Manchac. Due to Lake Maurepas’s shallow depths, even relatively low energy wave action results in sediment resuspension and, therefore, relatively high turbidities and low transparencies which influence the degree to which primary production can occur in the water column and benthos.