Lake Pontchartrain is an estuary in southeastern Louisiana in the United States. It covers 630 square miles (1,600 km2) with an average depth of 12 to 14 feet. 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.