Bayou Bienvenue is a 12.1 miles (19.5 km) bayou

Bayou

A bayou is an American term for a body of water typically found in flat, low-lying areas, and can refer either to an extremely slow-moving stream or river , or to a marshy lake or wetland. The name "bayou" can also refer to creeks that see level changes due to tides and hold brackish water which...

 in southeastern Louisiana

Louisiana

Louisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state in the U.S. with political subdivisions termed parishes, which are local governments equivalent to counties...

. It runs along the political border between Orleans Parish and St. Bernard Parish

St. Bernard Parish, Louisiana

St. Bernard Parish is a parish located southeast of New Orleans in the U.S. state of Louisiana. The parish seat is Chalmette, the largest city in the parish. As of 2000, its population was 67,229. It has been ranked the fastest-growing county in the United States from 2007 to 2008 by the U.S....

 to the east of New Orleans.

The bayou crosses the Gulf Intracoastal Waterway

Gulf Intracoastal Waterway

The Gulf Intracoastal Waterway is the portion of the Intracoastal Waterway located along the Gulf Coast of the United States. It is a navigable inland waterway running approximately 1700 kilometers from Carrabelle, Florida, to Brownsville, Texas.The waterway provides a channel with a controlling...

 and Mississippi River Gulf Outlet, before ending in Lake Borgne

Lake Borgne

Lake Borgne is a lagoon in eastern Louisiana of the Gulf of Mexico. Due to coastal erosion, it is no longer actually a lake but rather an arm of the Gulf of Mexico. Its name comes from the French word borgne, which means "one-eyed".-Geography:...

, a shallow coastal lake branching from the Mississippi Sound

Mississippi Sound

The Mississippi Sound is a sound along the Gulf Coast of the United States. It runs east-west along the southern coasts of Mississippi and Alabama, from Waveland, Mississippi, to the Dauphin Island Bridge, a distance of about 145 kilometers...

.

A short distance from the lake end, the remains of Battery Bienvenue

Battery Bienvenue

Battery Bienvenue is a ruined coastal gun battery located in St. Bernard Parish, Louisiana. It was built as part of the harbor defense of New Orleans, Louisiana and located at a strategic fork where Bayou Bienvenue and Bayou Villere join...

 still guard the eastern approach to the city. This fortification was built shortly after the Battle of New Orleans

Battle of New Orleans

The Battle of New Orleans took place on January 8, 1815 and was the final major battle of the War of 1812. American forces, commanded by Major General Andrew Jackson, defeated an invading British Army intent on seizing New Orleans and the vast territory the United States had acquired with the...

to prevent another attempt to invade through the lake and the bayou.