® MR&T PROJECT

US ARMY CORPS OF ENGINEERS  MISSISSIPPI VALLEY DIVISION  BUILDING STRONG®

MISSISSIPPI RIVER & TRIBUTARIES PROJECT

The Mississippi River and Tributaries 

project was authorized by the 1928 

Flood Control Act. In the wake of the 

devastating 1927 flood, it was 

deemed necessary to put into place 

a comprehensive, unified system of 

public works within the lower 

Mississippi Valley that would provide 

unprecedented flood risk management and an equally efficient 

navigation channel.

The MR&T project has four major 

features:

1. Levees/floodwalls

2. Tributary basin improvements

3. Floodways

4. Channel improvement and stabilization

These features work together to provide flood risk 

management and navigation, and foster environmental 

protection and enhancement.

• The Project Design Flood

The flood risk management plan is designed to control the 

"project design flood”. The present project design flood 

was developed in 1956 when the Mississippi River 

Commission made a complete review of the adequacy of 

the MR&T project. The National Weather Service was 

asked to provide the largest storm series considered to 

have a reasonable chance of occurrence in the season 

when floods are likely to occur over the Mississippi River 

Basin. After investigating 35 different hypothetical storm 

series, the one that produced the greatest discharges from 

Cairo, Ill., to the Gulf of Mexico was selected as the project 

design flood. The adequacy of the project design flood was 

reaffirmed following additional review in 1973. Following 

the 2011 Flood, the physical and hydraulic changes in the 

river system along with complex flow patterns observed, 

identified the need to validate the project design flood. 
• Levee Feature

MR&T levees are designed to reduce 

the risk of inundation in the alluvial 

valley from the project design flood 

by confining flow to the leveed area, 

except where backwater storage areas 

are used or \when water is diverted 

purposely into floodway areas. The 

risk reduction is provided from Cape 

Girardeau, Missouri, to Venice, Louisiana, 

about ten miles above the mouth of the 

Mississippi River. Some 3,727 miles 

of levees, including tributary levees, 

have been authorized for the MR&T 

and 3,486 miles are in place. Since 

inception of the project in 1928, no 

project levee built to MR&T standards 

has ever failed.

• Tributary Feature

Tributary improvements such as dams, 

levees, reservoirs, control structures, 

and pumping plants provide for flood 

risk management and drainage. While 

the Ohio, Upper Miss., Red and 

Arkansas/White river basins contribute 

to the significant flow of the Mississippi 

River, there are four major drainage 

basins that are contained entirely within 

the project: St. Francis in east 

Arkansas; Yazoo in northwest 

Mississippi; Tensas in northeast 

Louisiana; and Atchafalaya in south 

Louisiana. 

There are five flood risk management reservoirs in 

the tributary basin improvement plan: Wappapello

Lake in the St. Francis Basin, and four lakes –

Arkabutla, Sardis, Enid, and Grenada – in the 

Yazoo Basin.

• Floodway Feature

Floodways safely divert excess flows past critical 

reaches so that levee systems will not be unduly 

stressed and to minimize levee heights. There are 

three floodways in Louisiana and one in Missouri.
• Channel Stabilization Feature

Stabilization and protection of the river banks are critical to both flood risk management and navigation 

— by protecting flood control features and ensuring the alignment of the navigation channel. This is 

accomplished by: 

Cutoffs - to reduce 

flood heights and 

provide a more 

efficient channel 

(completed); 

Revetment - small 

concrete blocks joined 

together by wires 

placed on the river 

bank to maintain the 

proper channel alignment 

and protect nearby levees 

from bank erosion;

Dredging - to adjust 

river flow patterns 

and maintain navigable 

channels by deepening 

shallow areas that 

tend to form during low 

water stages, and

Dikes - large stone 

structures built 

perpendicular to the 

bank that direct most 

of the river flow to a 

single channel.
U.S. Army Corps of Engineers  1400 Walnut Street, Vicksburg, MS 39180  www.mvd.usace.army.mil

PROJECT BENEFITS

• Flood Protection

 $15.9 billion invested for planning, construction, operation and maintenance, since 1928

 $1.27 trillion in flood damages prevented, since 1928

 $206.5 billion in flood damages prevented in 2018

 80 to 1 return on each dollar invested

 4.5 million people protected

 The MR&T system has proven its value, particularly in recent years, as the system was tested 

and passed its third major flood in less than a decade with the Winter 2015/2016 event.

• Navigation

 669 million tons of cargo move on the Mississippi River System each year.

 $6.2 billion in domestic transportation savings.

 The Mississippi River remained opened during 1988, 1999 and 2012 droughts. The ability to keep 

the river open offered unequivocal evidence of the benefit of the MR&T project to the nation. 

PROJECT EXECUTION

The Mississippi Valley Division continues to evaluate activities across business lines with a riskbased approach; balancing the needs with the resources to meet the mission. Execution of the 

project involves balancing the investigation, construction, operations and maintenance 

requirements for flood risk management to: protect against the project design flood, provide a safe 

and reliable navigation channel, preserve and restore natural resources through environmental 

stewardship, ensure consistent recreational services to the public and provide water security for 

generations to come. Funding is used for the following purposes: General investigations, 

construction and maintenance. May 2019

PROJECT CHALLENGES

• Levees - The saying that a chain is only as strong as its weakest link is 

certainly true for a levee system. MR&T levees are designed using criteria 

which assure adequate cross-section and height and undergo inspections 

to identify problems and assure proper maintenance. Constant vigilance 

and maintenance are vital to the integrity of the MR&T levee system. 

• Channel Improvement & Stabilization - Much progress has been made 

in stabilizing the Mississippi River’s banks using revetments and dikes. 

These revetments and dikes protect the levees and flood risk management 

works from destruction by the river’s erosive power and maintain alignment 

for navigation. This critical work is important to the overall success of the 

flood risk management and navigation of the MR&T project. 

• Environmental Sustainability – The Lower Mississippi River Environmental 

Studies program began more than 20 years ago to help ensure sustainability 

of the natural habitats that exist in the valley. Numerous enhancements 

resulting from these studies include: dike notching, bio-friendly revetment 

surface treatment, improved borrow pit design and monitoring of endangered 

species including the interior least tern and pallid sturgeon. These important 

studies and environmental enhancements are needed to sustain diverse 

habitats for future generations.