evees are the backbone of the flood 

control plan for the Mississippi River 

and Tributaries (MR&T) project. The 

system protects the vast expanse of the 

developed alluvial valley from periodic 

overflows of the Mississippi River. The 

mainstem levee system begins at the head of the 

alluvial valley at Cape Girardeau, Mo., and 

continues to Venice, La., approximately 10 

miles above the Head of Passes near the Gulf of 

Mexico. The MR&T levee system includes 3,787 

miles of authorized embankments and 

floodwalls. Of this number, nearly 2,216 miles 

are along the mainstem Mississippi River. The 

remaining levees are backwater, tributary and 

floodway levees. 

The grade (height) and section (width) of 

the present levee system dwarfs, by 

comparison, those of the levee system that the 

Great Flood of 1927 overwhelmed with 

devastating effect. For instance, a typical 

mainline Mississippi River levee along the 

Yazoo front near Greenville, Miss., now stands 

30 feet tall and contains 907,000 cubic yards 

of material mile. In 1927, that same levee was 

only 22 feet high and contained only 421,000 

yards of cubic material per mile. 

In addition to higher and wider levees, the 

MR&T levee system design incorporates 

technological breakthroughs from the science 

of soil mechanics that take into account the 

type, condition and moisture content of 

material used in the construction of the levees. 

The integrity of the current levee system is 

enhanced by advancements in the design, 

construction, installation and maintenance of 

seepage control measures, to include landside 

berms, drainage trenches, drainage blankets 

and relief wells. More than 1,000 miles of 

articulated concrete mattress revetment also 

protect the levee system by preventing erosion. 

In an effort to further guarantee the 

soundness of the levee system, levee districts 

and other local sponsors implement strict 

annual levee maintenance programs with their 

own labor and funds. Activities include 

mowing, clearing brush and trees, filling holes, 

restoring rain washed areas, clearing drainage 

ditches, correcting drainage problems and 

spraying chemicals to control noxious and 

unwanted growth. Personnel from the Corps of 

Engineers ensure that maintenance 

requirements are met through annual 

inspections. These inspections are also used to 

identify any deficiencies and weak spots in the 

levee system so that immediate corrective 

actions can be taken. The addition of 16-foot 

wide, all-weather access roadways on top of the 

levee system aids federal personnel and local 

levee districts during the inspection process 

and during flood-fighting operations. 

To maximize protection from floods, current 

levee grades provide for freeboard - the 

distance between the project design flood 

flowline and the top of the levee. The presently 

authorized freeboard is a minimum of three 

feet above the project design flood on the 

Mississippi River levees below Cairo, Ill., and 

two feet on the Atchafalaya basin floodway 

levees. Levee grades between Cape Girardeau 

and Cairo and along the south banks of the 

Arkansas and Red rivers provide for a threefoot minimum freeboard over the maximum 

tributary flood meeting the maximum flood of 

record on the Mississippi River, with provisions 

to ensure that the same flood meeting the 

project design flood will not overtop the levee. 

In the vicinity of New Orleans, La., project 

levees are authorized up to 5.7 feet of freeboard 

because of the increased danger to the urban 

areas from wave wash and storm surges that 

are common along coastal areas. 

When flood stages begin to approach 

project design flood dimensions, additional 

project features, such as floodways, reservoirs 

History of the Lower Mississippi Levee System 

L 
2

and backwater areas, are operated to control 

and convey potentially damaging floodwaters 

to relieve stress on the levee system. 

Levee Evolution Prior to the MR&T Project 

Approximately 59 years before the signing 

of the Declaration of Independence, 85 years 

before the creation of the Corps of Engineers 

and 200 years before the first federal flood 

control act, the French began constructing the 

first levee on the Mississippi River in 1717 to 

protect the fledgling city of New Orleans from 

high water. That original levee was only three 

feet high and 5,400 feet long. The French, and 

later the Spanish, extended the modest levee 

system up the river, but progress was slow with 

the bulk of the work left to the landowners 

along the river. 

With the extension of American political 

control over the Mississippi Valley brought 

about by the Louisiana Purchase in 1803, the 

United States government moved to facilitate 

trade and develop the region’s rich economic 

potential through settlement. New settlers 

adopted aggressive flood-control tactics to 

protect their new settlements from inundation. 

Rather than only settling those lands less 

susceptible to overflow, the new frontiersmen 

also reclaimed lands well within the floodplain 

and constructed levees to protect them. They 

soon realized the difficult nature of the job. In 

addition to the original expense of their 

construction, the inadequate levee system 

required continual maintenance, repair and 

improvement. To that end, the landowners of 

the lower Mississippi Valley committed everincreasing resources to the task of protecting 

their lands from overflow. By 1812, when 

Louisiana gained statehood, cleared fields 

extended along the Mississippi River to the 

northern boundary of the state, with the levees 

extending from Caernarvon to the bluffs near 

Baton Rouge on the east bank and from just 

opposite Caernarvon to Morganza on the west 

bank. By 1844 levees on the west bank, with 

the exception of the gap at the mouth of the 

Red River, extended from 20 miles below New 

Orleans to the just below the mouth of the 

Arkansas River. 

The construction of levees had paralleled 

the growth of commerce. As the lower 

Mississippi Valley 

became more 

prosperous, the 

landowners grew 

increasingly anxious 

to protect their 

investments. 

Through the midnineteenth century, 

landowners assumed 

sole responsibility for 

the construction and 

maintenance of 

levees, but in 1849 

Louisiana led a 

congressional fight 

to secure the transfer 

of swamp and 

overflowed lands to 

the states of the 

Mississippi River & Tributaries Levees 
3

Mississippi River & Tributaries Levees 

Mississippi Valley, culminating in the Swamp 

Land Grants of 1849 and 1850. Revenue raised 

from the sale of those lands paid for further 

levee improvements and encouraged the 

organization of levee districts throughout the 

lower valley. Over time, these districts acquired 

substantial authority, including the power of 

eminent domain, the power of taxation within 

carefully defined limits and corporate authority. 

By 1858, the levee system reached its 

greatest extent up to that time. On the west 

bank, the line extended continuously from 45 

miles south of New Orleans 

to the Arkansas River, and 

intermittently from the 

Arkansas River to just 

opposite Cairo, Ill. On the 

east bank, the levees 

stretched from Pointe-a-laHache to the bluff at Baton 

Rouge and along the Yazoo 

front between Vicksburg 

and the MississippiTennessee state border. 

Successive floods in 1858 

and 1859, though, 

overwhelmed and damaged 

the fledgling levee system 

and proved conclusively 

that the system needed to be 

raised and strengthened. 

The people of the lower 

Mississippi Valley, however, had already 

expended $40 million on the damaged levee 

system. Nearing the end of their resources, they 

made strong appeals to the federal government 

for assistance, but the country soon 

disintegrated into civil war. Necessarily 

preoccupied, landowners and levee districts 

abandoned their levee repairs and maintenance 

responsibilities. Floods and military operations 

further damaged the system. Following the 

war, local interests struggled to promote a 

unified levee system under the strictest of 

financial constraints. Such efforts lacked 

centralized coordination and mostly failed. 

 The formation of the Mississippi River 

Commission June 28, 1879, certainly marked 

the beginning of a new era in levee 

development. With its creation, the federal 

government now appeared as an active agent 

capable of transcending regional issues that had 

long hampered the development of a more 

effective levee system. The commission, 

however, almost immediately was victimized by 

congressional legislation that prohibited the 

construction of levees with federal funds for the 

specific purpose of protecting property from 

overflow. 

After the 1882 flood, the commission 

adopted a levee policy that sought to join the 

unconnected lengths of levees into a continuous 

line. This policy was one of restraint in the 

interest of navigation that rested on the theory 

that the confinement of floodwaters would 

periodically flush out the channel and remove 

sand bars and other obstructions to navigation 

while still providing the incidental benefit of 

protection from overflow. Following the passage 

of the 1882 rivers and harbors legislation that 

authorized the new policy, the Mississippi River 

Commission began coordinating local efforts, 
4

setting standards and specifications for levee 

construction, and allocating federal funds to the 

cash-strapped levee districts. The levee districts, 

in turn, provided rights of way for federally 

sponsored levee work. Federal assistance with 

the levee system had remained limited to work 

done in the interest of navigation, commerce 

and the postal service, although the Mississippi 

River Commission continued to regard the levee 

lines as necessary for flood protection. 

Successive record-breaking floods in 1912 

and 1913, though, precipitated a crisis in the 

lower Mississippi 

Valley. In response to 

the floods, the 

commission 

established a new 

levee grade and 

section in 1914. In 

1882, a typical 

Mississippi River levee 

near Greenville stood 

only 8 feet high and 

contained 

approximately 31,500 

cubic yards of 

material per mile. 

Under the 1914 grade 

and section, that same 

levee would be 22 feet 

high and contain 

421,000 cubic yards 

of material. The 

commission estimated 

that it would cost $57 million to complete the 

system to the new grade and section. With this 

in mind, the tremendous expense incurred by 

local interests because of periodic inundation, 

combined with the cost of building, maintaining 

and repairing the levee system, was becoming 

prohibitive. Between 1882 and 1914, local 

interests had expended in excess of $91 million 

on levee construction to protect themselves 

from the ravages of the river—more than triple 

the amount of federal expenditures on the levee 

system during that same period. With 

establishment of the 1914 grade and section, 

local interests were being expected to 

contribute even more. Out of complete selfpreservation, landowners in the lower 

Mississippi Valley launched a massive 

campaign directed at obtaining greater federal 

commitment to their flood problem. 

 In 1917, Congress answered their pleas 

and passed the first federal flood control act, 

which authorized $45 million dollars over a 10

-year period to carry out the plans of the 

Mississippi River Commission. The act finally 

allowed for the expenditure of federal funds for 

the express and sole purpose of flood control 

and also eased the burden of local interests by 

only requiring them to contribute at least onethird of levee construction costs. After the 

passage of this act and the subsequent 1923 

flood control act, levee construction continued 

at an unprecedented pace, and by the close of 

1926 the levee system was nearing completion. 

In the fall of 1926, though, a vicious 

weather pattern stalled over much of the 

Mississippi River & Tributaries Levees 
5

Mississippi River & Tributaries Levees 

Mississippi River drainage basin, swelling the 

river and its tributaries. The rain saturated 

surrounding lands to the point that any 

additional precipitation immediately turned 

into runoff. Heavy rains continued from 

December through early spring, and in early 

January the first of three waves of floodwaters 

approached the lower Mississippi Valley. The 

successive flood crests overwhelmed the 

strengthened, but outmatched, levee system 

creating hundreds of crevasses, including 17 

major crevasses on the federal levees. By late 

April 1927, nearly 23,000 square miles of the 

valley were under water. 

Following the devastating 1927 flood, the 

nation was galvanized in its support for a 

comprehensive and unified 

system of public works 

within the lower 

Mississippi Valley that 

would provide enhanced 

protection from floods and 

an equally efficient 

navigation channel. Prior 

to that tragic flood event, 

the control of floods on the 

lower Mississippi was 

attempted by building 

levees high enough to 

withstand the last great 

flood of record. Since the 

inception of the MR&T 

project in 1928, however, the 

comprehensive flood control 

program has been designed to 

control the “project design flood.”

 In addition to adding the 

supplemental engineering 

techniques to the flood control 

system, the 1928 Flood Control 

Act also authorized higher levee 

grades and stronger levee sections. 

Through the 1928 act, Congress 

also recognized that cashstrapped local interests had 

contributed more than $290 

million toward the flood problem in the 

Mississippi Valley up to 1927. In order to 

facilitate navigation, protect interstate 

commerce and provide uninterrupted mail 

service, the federal government waived the 

local contribution requirement for the MR&T 

project levees and other flood control 

structures, provided the local levee districts 

granted all rights-of-way for levee foundations 

and levees and maintained and repaired the 

levees after their completion. 

The 1928 levee grade has since been revised 

following comprehensive reviews of the project 

in 1941, 1956 and 1973. 
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7

Drainage basin for 41% of the United States

Worlds 3rd Largest Watershed