riparian rap

The Fate of a Small Levee is in Question

Editor’s note: This post about the Len Small Levee was written by Steve Grimmer, Artist Mechanic at Little River.

Two barges remain on farmland in Alexander County, Illinois after being sucked through a breach in the Len Small Levee. August, 2019

Two barges remain on farmland in Alexander County, Illinois after being sucked through a breach in the Len Small Levee. August, 2019 (National Weather Service. Michael Schultz, photo.)

During the early spring months here in Southern Illinois, we keep an eye on the weather and on river levels. This is flood season, and living right above the confluence of the Mississippi and Ohio rivers can present special challenges to landowners in flood plains. In 2019, the Mississippi at Cape Girardeau, MO, “spent 145 days above flood stage and the majority of this time was spent above the moderate flood stage level. Cape Girardeau experienced their 5th highest crest on record, only two and a half feet below the record set back in January 2016.” (National Weather Service)  Among the many disasters brought on by such a prolonged flood was the breaching of the Len Small levee.

The Len Small Levee, named after the 26th governor of Illinois, is a small, farmer-built levee along the Mississippi River in Alexander County, Illinois. The area behind the levee is named Dogtooth Bend, after the U-shaped meander of the river that defines it, and has historically been exceptionally rich farmland because of the silt and sand deposited by seasonal floods over the eons. Locals noticed an increase in flood events early in the 20th century and built the levee in 1945 to protect their lands. The levee was a reliable barrier for nearly 50 years, but it has now been breached in 1993, 2011, and 2016, and experts say it’s likely to be breached again. A future break could well be a permanent rechanneling of the river, turning Dogtooth Bend into an island. Unbeknownst back in 1945, an effort to create equally rich farmland just across the river in Missouri’s bootheel region was one source of their troubles.

Map of Dogtooth Bend and surrounding area.

Map of Dogtooth Bend and surrounding area. (Kenneth Olsen, Impacts of 2011 Len Small levee breach on private and public Illinois lands. Journal of Soil and Water Conservation, July/August 2013)

In an article in the Journal of Soil and Water Conservation, March 2016, author Kenneth Olson of the University of Illinois explains that the bootheel region of southeast Missouri was originally a swampy hardwood forest in an ancient, nearly flat, abandoned channel of the Mississippi. It was actually one of the world’s largest bottomland forests. The Swamplands Act of 1850 gave states the rights to distribute undesirable, federally-owned swamplands as they saw fit. The idea was that local jurisdictions would drain the lands to create revenue-generating farmland, though this area was initially harvested of all its timber and left as a water-filled stumpland with no tax value. The Little River Drainage District was formed to drain this 1.2 million-acre area so that the bottomlands could be farmed. (Interesting naming coincidence noted.) The Little River Drainage Project of the 1920s was one of the great engineering projects of the day, and it moved more earth than the Panama Canal project!

Much of the rainwater runoff from the Ozark plateau in Missouri flows south into this region and was slowly conveyed into Arkansas and eventually the Mississippi River. The northern 720,000 acre part of this project is a series of three channels that flow north and east to the Mississippi just south of Cape Girardeau. The other 520,000 acre section is drained by five parallel canals south to the St. Francis River near Helena, Arkansas.

The farmers in southeast Missouri have been building levees along the Mississippi since the 1880s. But, shortly after the construction of the northern section of the drainage project, the people of Cape Girardeau, like their neighbors across the river, noticed an increase in flood intensity and started building a flood wall in 1957. The Southeast Missourian reported in 1964, “Engineers estimate it would take a flood stage of about 55 feet to top the wall that stands 17 to 20 feet in height. That stage is about 12 feet above any recorded flood here and about a foot above the theoretical maximum stage of water at Cape Girardeau, it was reported.” (It’s worth noting now that the floodwall is only 7 feet above the highest recorded stage.)

One factor in the increase of Mississippi river flooding here is the sudden influx of runoff water from the north LRDP channel. The densely wooded bottomland swamp formerly acted as a massive buffer, hanging onto floodwater and slowly releasing it into the St. Francis River. Another factor is ongoing efforts to raise levees after they are breached all along the river, effectively narrowing the channel, forcing water over other levees. These are then repaired and further raised in response. We have come to a point where the Len Small levee is perhaps no longer worth repairing. The cost may exceed the value of the land it is protecting, and even a higher repair is likely to be breached.

As I discussed in my last post about considering anthropogenic changes to the river itself when attempting to predict floods, we are seeing something of a feedback loop wherein raising a levee on the river forces other stakeholders to raise their levees in response. Assumptions about the river based on its behavior 50 or even 10 years ago may not be valid next year.  Going forward, we must find solutions that protect farmland and cities, but that also are river-smart and use everything we know from across disciplines so that our work is long-lasting and doesn’t cause more harm than good. Our Emriver stream tables and Structures Kit are excellent tools for teaching and studying a river’s response to levee walls and other manmade interventions.