Flooding in Louisiana
On this page you learn what types of flooding are typical in Louisiana and how do you protect yourself, your family and your home. You will also find out more about significant Louisiana floods. Finally, you'll find links to NWS offices that provide forecast and safety information for Louisiana, as well as links to our partners who play a significant role in keeping you safe.
Hurricane Katrina August and September 2005
Location: Mississippi and Louisiana, along with damages in Alabama, Florida, and inland states
Deaths: Over 1,800 in several states, with 1,577 in Louisiana
Injuries: Over 6,000; 700 still missing
Costs: Estimated $108 billion (2005 dollars) in damages total; estimated $81 billion in Louisiana
Impacts: Over 15 million people were impacted economically or otherwise
Hurricane Katrina made landfall as a Category 3 storm with winds of approximately 127 miles an hour. The storm made landfall near Grand Isle, Louisiana.
Fatalities: (directly or indirectly, FEMA)
- Alabama: 2
- Florida: 14
- Georgia: 2
- Louisiana: 1,577
- Mississippi: 238
- Total: 1,833
According to the Insurance Information Institute, 2010, insurance companies have paid an estimated $41.1 billion on 1.7 million different claims for damage to vehicles, homes, and businesses in six states. 63 percent of the losses occurred in Louisiana and 33 percent occurred in Mississippi. Hurricane Katrina is the costliest disaster in the history of the global insurance industry. By 2007, 99 percent of the 1.2 million personal property claims had been settled by insurers.
More than one million people in the Gulf region were displaced by the storm. At their peak hurricane relief shelters housed 273,000 people. Later, approximately 114,000 households were housed in FEMA trailers.
The federal government has spent $120.5 billion on the Gulf Region, post-Katrina. The majority of that money, $75 billion, went to emergency relief operations.
Drowning caused 40 percent of the deaths in Louisiana, by injury and trauma, 25 percent and heart conditions , 11 percent. Almost half the fatalities in Louisiana were people over the age of 74 according to the Greater New Orleans Community Data Center 2010
The population of New Orleans fell from 484,674 in April 2000 to 230,172 in July 2006, a decrease of over 50 percent. By 2012, the population has increased to 369,250. Some 70 percent of New Orleans' occupied housing, 134,000 units, was damaged in the storm. Source: Greater New Orleans Community Data Center 2013.
Hurricane Katrina made landfall on August 29, 2005. Rainfall totals of 8 to 15 inches occurred with the storm, in addition to the massive storm surge produced by the hurricane. All of the parishes around Lake Pontchartrain flooded, with some areas having storm surges to 16 feet. In Mississippi, storm surge flooding damaged the entire Gulf Coast, pushing debris as far north as Interstate 10. Homes, buildings, and businesses that survived Hurricane Camille were lost in Hurricane Katrina, with damages extending from Mobile, AL, westward. Roads, bridges, and other infrastructure were devastated at several locations.
According to Weather Underground, “The highest documented storm surge in the U.S. occurred in 2005 during Hurricane Katrina, when Pass Christian, MS, recorded a 27.8 foot storm surge above mean sea level. The highest High Water Mark on record for a U.S. hurricane occurred in Biloxi, MS during Katrina, where a High Water Mark of 34.1 feet above mean sea level was recorded on the outside of the Beau Rivage Casino Lighthouse. The surge was 22 feet high in Biloxi, so the combination of the tide (about 1 foot) and 11-foot waves on top of the storm surge created the 34.1-foot high water mark.”
Widespread flooding developed due to storm surge over southeastern Louisiana, mainly over Plaquemines, St. Bernard, Orleans, Tangipahoa, and St. Tammany Parishes (counties). Slidell and coastal cities in St. Tammany Parish were heavily damaged with waters from the Pearl River, as well as storm surge. Petrochemical operations in St. Bernard Parish were severely impacted and oil spills contaminated several areas of the parish. There were 30 oil rigs destroyed completely or damaged, with oil spills at 44 southeastern Louisiana facilities.
Although the hurricane passed to the east of New Orleans, 80 percent of New Orleans was flooded due to the failure of several levees as Hurricane Katrina moved north. The majority of the fatalities were in Louisiana, followed by Mississippi. Actual statistics of deaths and injuries are complicated by the fact that some people were treated or died while evacuating or settling in other places. Statistics show that 1,863 people lost their lives and 705 people are still missing to date. Over 6,000 injuries were reported to date.
According to the Department of Housing and Urban Development (HUD), 70 percent of the homes in St. Tammany Parish were damaged, 80 percent in Plaquemines Parish, and 81 percent percent in St. Bernard Parish. Several areas within the New Orleans Metropolitan Area were still damaged or in various states of repair as of 2014. The population has not rebounded to the pre- Katrina numbers for Orleans Parish.
Mississippi River Floods of 1927
Deaths: 246 flood-related deaths in several states
Impacts: Over 700,000 homeless in several states
Costs: Property damage was estimated at over $400 million dollars (1927 dollars), equivalent to over $5 billion dollars today.
The Great Mississippi Flood of 1927 was the most destructive flood in U.S. history. This flood extended across Illinois, Indiana, Missouri, Kentucky, Texas, Oklahoma, Kansas, Tennessee, Arkansas, Mississippi, and Louisiana. At one point the Mississippi River was approximately 80 miles wide near Vicksburg, MS.
According to the Louisiana Flood Insurance brochure, flood waters and damage in Louisiana was spread over 20 parishes consisting of a total of 10,000 square miles. New Orleans had 11.16 inches of February rainfall and that rainfall increased through March and the first half of April. On April 15--Good Friday--in excess of 14 inches deluged the city and overwhelmed the city's drainage pumps.
The political ramifications of this flood exacerbated the Great Migration of African-Americans from the impacted southern states to northern states. Conditions were harsher on the residents of Mississippi, where men were forced at gunpoint to rebuild the levees. In southeastern Louisiana, St. Bernard and Plaquemines Parishes were purposely flooded, when dynamite destroyed the Mississippi River levee at Caernarvon, LA to protect the city of New Orleans from the flooding.
National politics were impacted by the failure of the Republican politicians, particularly former Secretary of Commerce and President-elect, Herbert Hoover, to deliver on promises to African- Americans made during the elections of 1928. In upstate Louisiana, anger at the New Orleans elite aided Huey Long’s election to the governorship in 1928.[As a result, the political affiliations of many African-Americans switched from the Republican Party to Democratic Party.
Property damage was estimated at $350 million dollars, equivalent to approximately $5 billion dollars today. Economic losses were estimated at $1 billion (1927 dollars), which was equivalent to almost one-third of the federal budget at that time.
Floods from Hurricane Betsy August 27 to September 12, 1965
Deaths: Around 40 people in Louisiana, total of about 75 people
Costs: $1.4 Billion (1965 dollars) or $8.5 Billion
Hurricane Betsy tracked across the Windward Islands, the Bahamas, and southern Florida before moving into the Gulf of Mexico. Hurricane Betsy made landfall near Grand Isle, LA, on the night of September 9, 1965, as a Category 3 hurricane with winds over 140 miles an hour.
While in the Gulf of Mexico, Hurricane Betsy destroyed several offshore oil platforms, including one owned by the Shell Oil Corporation. Several other oil platforms had damages. The oil rig owned by Zapata Corporation was lost during the storm. That rig was insured for 5.7 million (1965 dollars) and was owned by the future President of the United States, George H. W. Bush.
According to the Time Picayune newspaper, Hurricane Betsy’s damages were widespread and heavily felt. Several southeastern Louisiana communities were devastated, particularly in St. Bernard and Plaquemines Parishes. New Orleans was flooded for about 10 days. There were breaches on both sides of the Industrial Canal during Betsy. In the storm's aftermath, the federal government sent trailers to house displaced families. The Times Picayune reported the remarkable similarity to Hurricane Katrina. The story stated, “The storm became the first billion-dollar hurricane, causing $1.2 billion in damage. In response to Betsy, Congress ordered the Army Corps of Engineers to build a massive flood-protection system for New Orleans. That system fell apart 40 years later during Hurricane Katrina.”
Strong winds and heavy rainfall caused significant crop damage in Harrison, Hancock County, and Jackson counties, MS. Throughout the state, 25,000 people lost electricity and more than 22,641 disruptions to telephone service occurred. Overall, damage in the state of Mississippi totaled to $80 million (1965 USD), according to Wikipedia.
Damaged U.S. Quarantine Station in New Orleans. Source: U.S. National Library of Medicine website.
Mississippi River Flood of April-May 2011
Deaths: Approximately 20 in several states; Army Corps of Engineers reported no deaths.
Injuries: No reports on injured found.
Costs: About $2 to $4 Billion (2011 dollars)
Impacts: Approximately 3,500 people were evacuated in the Atchafalaya River Basin; estimated that one-third of Wilkerson County, MS, flooded.
The massive flooding that developed during the early spring of 2011 rivaled the Mississippi River Floods of 1927 and 1937, according to the Encyclopedia Britannica. According to the article, “Concerns that the levees could be breached in the Louisiana cities of Baton Rouge and New Orleans--displacing thousands of people and shutting down a network of petroleum refineries that accounted for a substantial portion of domestic gasoline production--led to the opening of two spillways in May. With waters approaching the 1.25 million cubic feet (35,000 cubic meters) per second rate that indicated a possible risk to the cities, on May 9 the Bonnet Carre Spillway, approximately 30 miles (50 km) north of New Orleans, was partially opened, allowing overflow into Lake Pontchartrain, which drains into the Gulf of Mexico. Further channels were opened the following days. On May 14 the Morganza Spillway, about 35 miles (56 km) north of Baton Rouge, was partially opened before more channels opened in the ensuing days. Nearly 3,500 people were evacuated. Those waters drained into the Atchafalaya River basin, covering some 3,000 square miles (7,770 square km), much of it cropland.”
In all, the diversion of flow into Lake Pontchartrain and eventually the Gulf of Mexico waylaid the worst of the flooding, particularly after the opening of the Morganza Spillway by the Army Corps of Engineers. Approximately 3,000 square miles of cropland was flooded within the lower portion of the Atchafalaya River basin. The flooding impacts of St. Mary, St. Landry, Avoyelles, Iberia, and St. Martin Parishes were far less than what would have occurred without the diversion of the flood waters.
Major costs associated with this flood were suffered by farming and fishing sectors, the petrochemical industry, and by the river boat/barge and shipping industries which operate along the Ohio, Missouri, and Mississippi Rivers. From the Corps of Engineers report, “Total flood damage estimates from the 2011 Flood, totaled over $2.8 billion in urban and agricultural damages.” Environmental impacts included damage to coastal estuaries, displacement of native fauna, and ongoing impacts of reduced salinity in Lakes Maurepas and Pontchartrain. According the Corps’ report, the flood adversely impacted the oyster industry in the Mississippi Sound, Lake Borgne, and Breton Sound in Louisiana. Economic losses to the oyster industry in Mississippi alone in 2011 were approximately $60 million, according to the report.
New flood records were recorded upstream along the Mississippi River at Natchez and Vicksburg, MS. Roughly one-third of Wilkinson County was flooded in May 2011. A new record stage was set at Knox Landing, LA, where the Mississippi River rose to 66.26 feet on May 18th. On that same date, the flood waters rose to a new record stage of 63.39 feet at Red River Landing. A recently-established gauge on the Mississippi River at St. Francisville, LA set a new flood record of 53.48 feet on May 18th, as well.
Floods of May 8-10, 1995
Impacts: $3.1 billion
Starting on May 8, 1995, severe floods caused extensive damage in southeastern Louisiana and southern Mississippi. The floods shut down the New Orleans metropolitan area, after storm totals of 10 to 20 inches fell over the region.
The May 1995 floods were more extensive and damaging than the Easter Floods of 1979 and the Floods of 1989. The May 1995 flooding was more costly than these two events combined. There has been no comparable recorded flood in New Orleans caused by rain alone.
New Orleans suffered $360 million in damages, and the damage of the surrounding areas put that total above $3 billion, according to National Weather Service. Some 56,000 homes were damaged in 12 Parishes. Thousands of cars were flooded. 14,600 homes and apartments were flooded in Jefferson Parish alone.
Rain totals from this event include:
- Abita Springs, LA: 24.46"
- Necaise, MS: 27.50"
- New Orleans (Tulane University), LA: 24.05"
- New Orleans (International Airport), LA: 9.67"
- New Orleans (Lakefront Airport), LA: 15.44"
- Slidell, LA: 19.09"
Flash flooding is a rapid and extreme flow of high water into a normally dry area, or a rapid water level rise in a stream or creek above a predetermined flood level, beginning within six hours of the causative event (i.e., intense rainfall, dam failure, ice jam). More information...
River flooding occurs when river levels rise and overflow their banks or the edges of their main channel and inundate areas that are normally dry. More information...
Tropical Systems and Coastal Flooding
At any time of year, a storm from over the ocean can bring heavy precipitation to the U.S. coasts. Whether such a storm is tropical or not, prolonged periods of heavy precipitation can cause flooding in coastal areas, as well as further inland as the storm moves on shore. More information...
A back-up of water into surrounding areas can occur when a river or stream is blocked by a build-up of ice or other debris. Debris Jam: A back-up of water into surrounding areas can occur when a river or stream is blocked by a build-up of debris. More information...
Dam Breaks/Levee Failure
A break or failure can occur with little to no warning. Most often they are caused by water overtopping the structure, excessive seepage through the surrounding ground, or a structural failure. More information...
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