2011 Mississippi River floods

2011 Mississippi River floods

100 populated locations were experiencing major or moderate flooding on May 8, 2011. Source: National Weather Service
Date	May 4, 2011 to June 20, 2011
Location	Mississippi River Valley, United States
Deaths	About 20 direct 348 indirect from preceding storms[1][2][3]
Property damage	US$2 to 4 billion[4][5]

Major floods along the Mississippi River in April and May 2011 were among the largest and most damaging recorded along the U.S. waterway in the past century, comparable in extent to the Great Mississippi Flood of 1927 and Great Flood of 1993. In April 2011, two large storm systems deposited record levels of rainfall on the Mississippi River drainage basin. When that additional water combined with the springtime snowmelt, the river and many of its tributaries began to swell to record levels by the beginning of May. Flooding occurred in Illinois, Missouri, Kentucky, Tennessee, Arkansas, Mississippi, and Louisiana.

U.S. President Barack Obama declared the western counties of Kentucky, Tennessee, and Mississippi federal disaster areas.^[6] For the first time in 37 years, the Morganza Spillway was opened on May 14, deliberately flooding 4,600 square miles (12,000 km²) of rural Louisiana to save most of Baton Rouge and New Orleans.^[7]

Fourteen people were killed in Arkansas,^[8] with 348 killed across seven states in the preceding storms.^[1][2][3] Thousands of homes were ordered evacuated, including over 1,300 in Memphis,^[9] and more than 24,500 in Louisiana and Mississippi,^[10][11] though some people disregarded mandatory evacuation orders.^[12] The flood crested in Memphis on May 10 and artificially crested in southern Louisiana on May 15, a week earlier than it would have if spillways had not been opened.^[13] The United States Army Corps of Engineers stated that an area in Louisiana between Simmesport and Baton Rouge was expected to be inundated with 20–30 feet (6.1–9.1 m) of water.^[14] Baton Rouge, New Orleans, and many other river towns were threatened,^[15][16] but officials stressed that they should be able to avoid catastrophic flooding.^[17]

From April 14–16, the storm system responsible for one of the largest tornado outbreaks in U.S. history also produced large amounts of rainfall across the southern and midwestern United States. Two more storm systems, each with heavy rain and tornadoes, hit in the third week of April. In the fourth week of April, from April 25–28, another, even more extensive and deadly storm system passed through the Mississippi Valley dumping more rainfall resulting in deadly flash floods.^[18] The unprecedented extensive rainfall from these four storms, combined with springtime snow melt from the Upper Midwest, created the perfect situation for a 500-year flood along the Mississippi.