Lake Maurepas, Freshwater lake near New Orleans, United States

Lake Maurepas is a freshwater lake in southeastern Louisiana connected to Lake Pontchartrain through Pass Manchac. The body of water is fed by four rivers, keeping its salt content low and creating a landscape dominated by cypress and tupelo swamps.

In 1699 the French explorer Pierre Le Moyne d'Iberville named the lake for Louis Phélypeaux, comte de Maurepas, chancellor and secretary of state for the navy under Louis XIV. The English Wikipedia instead credits Jean-Frédéric Phélypeaux, son of the comte de Pontchartrain, for whom the neighbouring lake is named. The name thus records the family that administered French naval and colonial affairs.

The lake's name honors Jean-Frédéric Phélypeaux, comte de Maurepas, son of the comte de Pontchartrain, for whom the neighboring lake is named. The Maurepas Swamp Wildlife Management Area, established with a 61,633-acre donation from the Richard King Mellon Foundation, now covers 122,098 acres along the south shore. The Manchac Swamp Bridge carries Interstate 55 across the strip between the two lakes.

Access to the lake is mainly by boat, since the south shore is marsh and swamp within the Maurepas Swamp WMA, about 40 km northwest of New Orleans. Interstate 55 crosses the strip between Lake Maurepas and Lake Pontchartrain on the Manchac Swamp Bridge. The lake is shallow, about 3 m deep, and turbid, so expect low visibility in the water.

The lake is the proposed site of a carbon sequestration project by Occidental Petroleum and Air Products. In 2025, researcher Fereshteh Emami was removed from leading water-quality work after her team reported arsenic, lead and cadmium at alarming levels, traced to runoff from the Blind, Tickfaw and Amite rivers.