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Lake Pontchartrain ( ; , ) is a brackish estuary located in southeastern Louisianamarker. It is the second-largest saltwater lake in the United Statesmarker, after the Great Salt Lakemarker in Utahmarker, and the largest lake in Louisiana.It covers an area of 630 square miles (1630 square km) with an average depth of 12 to 14 feet (about 4 meters). Some shipping channels are kept deeper through dredging. It is roughly oval in shape, about 40 miles (64 km) wide and 24 miles (39 km) from south to north. In descending order of area, the lake is located in parts of St. Tammanymarker, Orleansmarker, Jefferson, St. John the Baptistmarker, St. Charlesmarker, and Tangipahoamarker parishes.


Lake Pontchartrain is named for Louis Phélypeaux, comte de Pontchartrain, the Frenchmarker Minister of the Marine, Chancellor of France and Controller-General of Finances during the reign of France's "Sun King," Louis XIV, for whom Louisiana is named.


Lake Pontchartrain is not a true lake but an estuary connected to the Gulf of Mexicomarker via the Rigolets strait (known locally as "the Rigolets") and Chef Menteur Pass into Lake Borgnemarker, another large lagoon, and therefore experiences small tidal changes. It receives fresh water from the Tangipahoa, Tchefuncte, Tickfaw, Amite, and Bogue Falaya Rivers, and from Bayou Lacombe and Bayou Chinchuba.

Salinity varies from negligible at the northern cusp west of Mandeville up to nearly half the salinity of seawater at its eastern bulge near Interstate 10. Lake Maurepasmarker, a true fresh water lake, connects with Lake Pontchartrain on the west via Pass Manchac. The Industrial Canalmarker connects the Mississippi River with the lake at New Orleansmarker. Bonnet Carré Spillwaymarker diverts water from the Mississippi into the lake during times of river flooding.


The lake was created 2,600 to 4,000 years ago as the evolving Mississippi River Deltamarker formed its southern and eastern shorelines with alluvial deposits. Its Native American name was Okwata ("Wide Water"). In 1699, Frenchmarker explorer Pierre Le Moyne d'Iberville renamed it Pontchartrain after Louis Phélypeaux, comte de Pontchartrain.

Human habitation of the region began at least 3,500 years ago, but increased rapidly with the arrival of Europeans about 300 years ago. The current population is over 1.5 million. The United States Geological Survey is monitoring the environmental effects of shoreline erosion, loss of wetlands, pollution from urban areas and agriculture, saltwater intrusion from artificial waterways, dredging, basin subsidence and faulting, storms and sea-level rise, and freshwater diversion from the Mississippi and other rivers.


North of Lake Pontchartrain is an area called the North Shore or Northshore or the Northlake area. It is composed of cities such as Mandevillemarker, Covingtonmarker, Abita Springsmarker, Madisonvillemarker, Lacombemarker, Slidell in Saint Tammany Parish; Ponchatoulamarker, Hammondmarker, and Amitemarker in Tangipahoa Parish; and Franklintonmarker and Bogalusamarker in Washington Parish. These Northshore parishes form the eastern Florida Parishes. They constitute most of the primary service area for Southeastern Louisiana Universitymarker in Hammond and are coterminous with ZIP codes beginning with "704" (Southeastern's five digit ZIP code, for example, is 70402).

The Southshore areas, instead of being designated by that name, are more likely to be referred to as either "Eastbank" or "Westbank" depending on their position with respect to the general direction of flow of the Mississippi River. Lake Ponchartrain forms the northern boundary of the city of New Orleansmarker, which is coterminous with Orleans Parishmarker, and its two largest suburbs Metairiemarker and Kennermarker as well as the northern boundary of Jefferson Parish and Saint Charles Parishmarker and much of the northern and eastern boundaries of Saint John the Baptist Parish.

New Orleans

New Orleans was established at a Native American portage between the Mississippi River and Lake Pontchartrain. The lake provides numerous recreational activities for people in New Orleans and is also home to the Southern Yacht Club. In the 1920s the Industrial Canalmarker in the eastern part of the city opened, providing a direct navigable water connection, with locks, between the Mississippi River and the lake. In the same decade, a project dredging new land from the lake shore behind a new concrete floodwall began; this would result in an expansion of the city into the former swamp between Metairie/Gentilly Ridges and the lakefront. The Lake Pontchartrain Causewaymarker was constructed in the 1950s and 1960s, connecting New Orleans (by way of Metairie) with Mandeville and bisecting the lake in a north-northeast line. At 24 miles (39 km), the Causeway is the longest bridge over a body of water in the world.


During hurricanes, a storm surge can build up in Lake Pontchartrain. Wind pushes water into the lake from the Gulf of Mexico as a hurricane approaches from the south, and from there it can spill into New Orleans.

A hurricane in September, 1947 flooded much of Metairie, Louisianamarker, much of which is slightly below sea level due to land subsidence after marshland was drained. After the storm, hurricane-protection levees were built along Lake Pontchartrain's south shore to protect New Orleans and nearby communities. A storm surge of 10 feet (3 m) from Hurricane Betsy overwhelmed some levees in Eastern New Orleans in 1965 (while storm surge funneled in by the Mississippi River Gulf Outlet Canalmarker and a levee failure flooded most of the Lower 9th Wardmarker). After this the levees encircling the city and outlying parishes were raised to heights of 14 to 23 feet (4-7 m). Due to cost concerns, the levees were built to protect against only a Category 3 hurricane; however, some of the levees initially withstood the Category 5 storm surge of Hurricane Katrina (August 2005), which only slowed to Category 3 winds within hours of landfall (due to a last-minute eyewall replacement cycle).

Experts using computer modeling at Louisiana State Universitymarker subsequent to Hurricane Katrina have concluded that the levees were never topped but rather faulty design, inadequate construction, or some combination of the two were responsible for the flooding of most of New Orleans: some canal walls leaked underneath because the wall foundations were not deep enough in peat-subsoil to withstand the pressure of higher water.


Congress failed to fully fund an upgrade requested during the 1990s by the Army Corps of Engineers, and funding was cut in 2003-04 despite a 2001 study by the Federal Emergency Management Agency warning that a hurricane in New Orleans was one of the country’s three most likely disasters. Raising and reinforcing the levees to resist a Category 5 hurricane might take 25 years to complete. Some estimates place the cost at $25 billion.

Hurricane Katrina

When Hurricane Katrina reached Category 5 in 2005, some experts predicted that the levee system might fail completely if the storm passed close to the city. Although Katrina weakened to a Category 3 before making landfall on August 29 (with only Category 1-2 strength winds in New Orleans on the weaker side of the eye of the hurricane), the outlying New Orleans East along south Lake Pontchartrain was in the eyewall with winds, preceding the eye, nearly as strong as Bay St. Louis, MSmarker. Canals near Chalmettemarker began leaking at 8 am, and some levees/canals, designed to withstand Category 3 storms, suffered multiple breaks the following day (see Effect of Hurricane Katrina on New Orleans), flooding 80% of the city.

The walls of the Industrial Canalmarker were breached by storm surge via the Mississippi River Gulf Outletmarker, while the 17th Street Canal and London Avenue Canal experienced catastrophic breaches, even though water levels never topped their flood walls. Louisiana State Universitymarker experts presented evidence that some of these structures might have had design flaws or faulty construction.

There are indications that the soft earth and peat underlying canal walls may have given way. In the weeks before Katrina, tests of salinity in seepage pools near canals showed them to be lake water, not fresh water from broken mains. The 5.5 mile (9 km) long I-10 Twin Span Bridgemarker heading northeast between New Orleans and Slidell was destroyed. The shorter Fort Pike Bridge crossing the outlet to Lake Borgne remained intact.

Much of the northern sector of the suburban areas of Metairie and Kenner was flooded with up to 2-3 feet of water. In this area, flooding was not the result of levee overtopping, but was due to a decision by the governmental administration of Jefferson Parish to abandon the levee-aligned drainage pumping stations. This resulted in the reverse flow of lake water through the pumping stations into drainage canals which subsequently overflowed, causing extensive flooding of the area between I-10 and the lakefront. When the pump operators were returned to their stations, water was drained out of Metairie and Kenner in less than a day, in some cases, only a few hours.

On September 5, 2005, the Army Corps of Engineers started to fix levee breaches by dropping huge sandbags from Chinook helicopters. The London Avenue Canal and Industrial Canal were blocked at the lake as permanent repairs started. On September 6, the Corps began pumping flood water back into the lake after seven days in the streets of New Orleans. Because it was fouled with dead animals, sewage, heavy metals, petrochemicals, and other dangerous substances, the Army Corps worked with the U.S. Environmental Protection Agency‎ and Louisiana Department of Environmental Quality (LDEQ) to avoid major contamination and eutrophication of the lake. (Dead link)

Aerial photography suggests that 25 billion gallons (95 bn liters) of water covered New Orleans as of September 2, which equals about 2% of Lake Pontchartrain's volume. Due to a lack of electricity, the city was unable to treat the water before pumping it into the lake. It is unclear how long the pollution will persist and what its environmental damage to the lake will be, or the hazards from the mold and contaminated mud remaining in the city.

On September 24, 2005, Hurricane Rita did not breach the temporary repairs in the main part of the city, but the repair on the Industrial Canal wall in the lower 9th ward was breached, allowing about of water back into that neighborhood.

Popular culture

Notable deaths

  • Eastern Air Lines Flight 304 crashed into the lake on February 25, 1964, resulting in the deaths of 51 passengers and 7 crew. Very little of plane and passengers was ever able to be recovered after the crash.
  • September 15, 1978- Six year old, Benjamin Daly died when a private plane his parents had chartered crashed into the lake. His parents survived but Benjamin and the pilot perished.
  • In 1985, a decomposing woman's body was found by two fishermen. The cause of death was homicide by asphixia. She was not identified and no leads were ever identified in the case.
  • New England Patriots defensive end Marquise Hill was found dead in Lake Pontchartrain on May 28, 2007.

See also


Further reading

  • Lake Pontchartrain, 2007, ISBN 978-0-7385-4392-5

External links

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