As August begins, the Missouri River remains outside of its normal banks in numerous locales. Accordingly, many people, up and down the river, seek information regarding this unprecedented natural disaster. As a result, each day, the U.S. Army Corps of Engineers, Missouri River Joint Information Center strives to fully answer the numerous flood related questions it receives.
In an ongoing effort to help the public better understand the many aspects of this flooding, the following answers to commonly asked questions are provided.
This week, the topic addressed is the Missouri River levee system and the role that the Corps has in regards to the building and operation and maintenance of these levees.
What is the Corps’ responsibility regarding the levees along the Missouri River?
The Flood Control Act of June 22, 1936 tasked the Corps with certain responsibilities regarding this type of natural disaster. Beyond the main stem dam and reservoir system - along the entirety of the Mighty Mo’s 2,321 mile length – it has constructed nearly 1,000 miles of levees. The Omaha District’s area of levee responsibility is from Omaha to Rulo, Neb., and the Kansas City District’s is from Rulo to St. Charles, Mo.
With the exception of 30 miles near dams or abutting federal land, once completed and fully certified, these "Federal Levees" have been turned over to non-federal, local "sponsors" comprised of public agencies - often municipalities or levee and drainage districts. Though these earthen structures are regularly inspected by the Corps, they are the responsibility of th e sponsor for operation and maintenance.
A "non-Federal levee" was not designed, built, nor is managed by the U.S. Army Corps of Engineers. Some are Public Law 84-99 approved (described later) others are not. The responsibilities required of both local levee owners and Corps project sponsors are broad. They include: levee safety; land use planning and development; building codes; and operations, maintenance, repair, rehabilitation and replacement of the levee. Certifying the levee data submitted to the Federal Emergency Management Agency for accreditation under the National Flood Insurance Program is also the responsibility of the local levee owner or sponsor.
An often misunderstood fact is that congressionally mandated responsibilities by the Corps is for Federal and PL 84-99 levees only.
Who is responsible for the rest of the levees along the river?There are other private levees constructed by individual landowners, but the Corps does not keep a record of them if they are not within the dictates of PL 84-99.
What is Public Law 84-99?This law limits rehabilitation assistance to damaged Federal and non-Federal Flood Control Works such as levees that are in an active status in the Rehabilitation and Inspection Program (RIP) at the time of the flood event.
Rehabilitation Assistance is limited to repair or restorat ion of a Flood Control Works to their pre-disaster condition and level of protection. There is a designated procedure and time-line to initiate, determine eligibility, identify the extent of work required and the cost of such activity. Rehabilitation of non-Federal projects are cost shared at 80 percent federal and 20 percent from the sponsor.
What problems can levees encounter during flooding?During a flood the stability of levees can be compromised in a variety of ways, such as:
Overtopping occurs when water levels exceed the height of the levee and flows over it.
A sand boil develops when water begins seeping underneat h the levee and starts bubbling, or "boiling" up, on the other side. If the sand boil is moving material with the water (otherwise known as piping) this is evidence of potential damage to the levee. Sand boils can occur hundreds of yards away from the levee.
The breach occurs when the structural integrity of the levee is damaged and water begins flowing under or through it. As water seeps under or through the levee, it can cause the levee to collapse in some areas, allowing water to flow through the gap. A partial breach tends to lead to a full breach taking out a full segment of the system or failure of the entire system.
Scouring can result from flows on the river side of a levee which, if left unattended, can threaten the integrity
Why have some levees breached during this flood? There are a variety of reasons that may lead to a levee breach, including weakening by tree roots, rodent holes, seepage, erosion, relief well failures (vertical wells or boreholes landside of a levee that collect and control seepage through or under the levee to reduce water pressure), and slope stability issues.
The Corps team strives to be as responsive as possible to the public it serves through a myriad of means:
Facebook – www.facebook.com/OmahaUSACE and www.facebook.com/OperationMightyMo
Omaha District Web site - www.nwo.usace.army.mil
For general questions regarding our flood response information efforts, please call (402) 996-3877 or e-mail us at MRJIC@usace.army.mil.