Lake Pontchartrain

Lake Pontchartrain from southbound causeway entrance Lake Pontchartrain's north shore at Fontainebleau State Park near Mandeville, Louisiana, in 2004 Lake Pontchartrain (/ˈpɒntʃətreɪn/ PON-chə-trayn; French: Lac Pontchartrain, pronounced [lak pɔ̃ʃaʁtrɛ̃] ) is an estuary in southeastern Louisiana in the United States. It covers 630 square miles (1,600 km) with an average depth of 12 to 14 feet (3.7 to 4.3 m). Some shipping channels are kept deeper through dredging. It is roughly oval, about 40 miles (64 km) from west to east and 24 miles (39 km) from south to north. As an estuary, its "Lake" title is a misnomer, but only a slight one, as its passage to the open sea is narrow.

The lake was named in 1699 by the French explorer Pierre Le Moyne d'Iberville for Louis Phélypeaux, comte de Pontchartrain, a minister under Louis XIV. It connects to the Gulf of Mexico through the Rigolets strait and Chef Menteur Pass by way of Lake Borgne, and receives fresh water from several rivers and bayous, giving it brackish water and only small tidal changes. Lake Pontchartrain is one of the largest wetland systems along the Gulf Coast of North America and forms the core of the wider Pontchartrain Basin, a watershed that spans 16 Louisiana parishes and four Mississippi counties.