UPDATE: On Tuesday, May 3, 2011 Michael Reuter, director of The Nature Conservancy’s North America Freshwater Program, reports from Sikeston, MO, site of record flooding on Sunday, May 1. You can watch his dispatch from before the levee was breached here.
News about flooding in the Midwest has focused on a very specific and dramatic debate swirling at its center. The breathless coverage describes a seemingly last-ditch, desperate proposal by the U.S. Army Corps of Engineers to blow up a levee and send a torrent of floodwater across 130,000 acres of Missouri cropland. By breaching the levee and sacrificing the farms, the Corps hopes to lower the level of the Mississippi River and relieve pressure against other levees protecting the town of Cairo, Illinois.
The story packs great drama as it pits town against farmer, one state against another, and state leaders against a federal agency: Missouri Governor Jay Nixon has taken the Army Corps to Federal Court in a bid to stop their plan.
However, this drama obscures some important insights about how we manage floods and floodplains. Here I’d like to untangle this twisting plot and try to add some light about sustainable flood management to the heat of the flood drama.
Most of the news coverage provides little context for the Corps’ plan to intentionally breach the levee. I looked at several articles from major outlets and most would leave a reader with the impression that the Corps, alarmed by rising river levels, concocted the breach idea in a fit of distressed improvisation. An AP story characterized the proposal as a “desperate plan,” and later noted, “The idea was hatched as a desperate bid to reduce the amount of water moving down the Mississippi.” One article reported that the levee breach will impact “huge numbers of families.”
And it was very hard to find an article that mentioned one crucial point. The 130,000 acres the Corps proposes to intentionally flood has a name: the New Madrid Floodway. Simply using that term—floodway—would certainly have shed some light on this debate.
An accurate sentence describing this controversy could read as follows: “Faced with possibly the highest river levels ever recorded at the junction of the Mississippi and Ohio Rivers, the Army Corps of Engineers has announced that, if necessary to protect lives and property, it will divert approximately one-fourth of the Mississippi River’s flow into the New Madrid Floodway. The New Madrid Floodway was authorized by Congress in 1928 in response to the cataclysmic 1927 Mississippi flood. By allowing the intentional flooding of select areas like the New Madrid Floodway, cities, towns and farms along the river can have greater security from flood disasters.”
I admit the above paragraph is pretty dry.
But it contains the essential elements of an even more dramatic story than the one unfolding today. The 1927 flood on the Mississippi was the most damaging river flood in U.S. history, levees failed in 150 places, inundating 27,000 square miles—nearly the area of South Carolina—and displacing 600,000 people and causing 246 deaths.
The flood also utterly obliterated the prevailing paradigm for managing floods, the “levees only” approach. After the 1927 flood, the engineers tasked with managing flood risk on the Mississippi realized that the rivers’ floods were simply too large to contain within levees along the river channel and that, during the largest floods, some floodwaters must be allowed to flow across the historic floodplain in order to reduce pressure on levees. With the Flood Control Act of 1928, Congress authorized the Corps of Engineers to undertake a comprehensive project for managing floods on the Mississippi. This project created the New Madrid and three other floodways—large areas of floodplain strategically located to receive floodwaters that can enter the floodway only if the river reaches a specific flood height (see a map of the floodways here).
The New Madrid Floodway has only been used once, in 1937 (when the Corps discovered the “fuseplug” levee wouldn’t give way as intended and thus needed some dynamite encouragement). In preparation for the possibility of breaching the levee, the 300 people who live within the approximately 100 homes within the Floodway have been evacuated.
Although the story has crystallized around farmers vs. the town of Cairo, the Corps points out that much more is at stake. If the Floodway levee must be breached, that action could lower the Mississippi River water level by as much as 7 feet, relieving pressure not just on Cairo’s levees but also on those that protect other towns and hundreds of thousands of acres of farmland.
More broadly, the 1927 flood painfully taught us an important lesson, and one that has been affirmed many times since: relying only on levees to hold is not a safe strategy. The response to that flood was to require more resiliency in the system and to allow floodplains to do some of the levees’ work.
We must continue to follow that lesson today. Despite massive investments in levees, flood damages continue to rise in the U.S., averaging more than $3 billion in damages per year in recent decades compared to less than $1 billion per year 80 years ago (in constant dollar values).
But we can continue to build resiliency into the system and let the floodplains do some of the work for us. By collaborating with willing landowners and finding innovative solutions, we can find locations to strategically reconnect rivers with their floodplains in order to reduce flood risk to surrounding towns and farms. In addition to helping reduce flood risks, floodplains are critically important ecosystems that provide a number of other benefits to people, such as filtering sediment and pollution from water and providing habitat for fish, wildlife and waterfowl.
For example, the Conservancy’s Great Rivers Partnership has worked with agricultural landowners and agencies to restore floodplains. A recent project at a place called Mollicy Farms in Louisiana reconnected 18,000 acres of floodplain to the Ouachita River. Although the project was not focused on flood-risk reduction, a flood event in 2009 illustrates what can happen when the Ouachita’s floodwaters can access the Mollicy Farms floodplain. In May, the river beat conservationists to the punch by breaching the levees a few months in advance of an intentional breach. Downstream, a river gage showed a rapid decline in the river level (see graph below) just after the levees were breached and water moved onto the floodplain. This illustrates the potential for floodplain reconnection to reduce risk to nearby towns and farms.
I’m sure the 300 people who live in the New Madrid Floodway feel no consolation in the fact that the Floodway represents a more sustainable and resilient approach to flood management than strict reliance on levees. The Floodway has not been used in 74 years so no doubt, to them, it does not feel like a floodway. Rather it is their land, their legacy. The Corps is faced with a very difficult decision and we can only hope that they are able to select the most effective choice for public safety.
The level of the Ouachita River at a gage downstream of Mollicy Farms. The arrow shows the moment that levees at Mollicy breached, allowing floodwaters to move onto the 18,000 acre floodplain.
(Top image: Dynamiting a levee at Caernarvon, Louisiana during the 1927 flood. Unlike the current debate over the intentional levee breach to flood the New Madrid Floodway, the 1927 intentional levee breach was an improvised action intended to save New Orleans from flooding (due to the great number of flood-caused levee breaches upstream, this action was likely not needed). The intentional levee breach flooded two Louisiana parishes. Although residents had been evacuated, the flood caused great economic hardship. Image credit: US Army Corps of Engineers)