Floodplains

Mississippi and Missouri Rivers are the greatest rivers in North America. Consequently, Missouri has large areas of land exposed to regular or intermittent flooding along the rivers and streams of the state. Missouri ’s floodplains vary from areas along small creeks subject to flash flooding in heavy rains to the 80,000 acre floodplain at the confluence of the Missouri and Mississippi Rivers in St. Charles County .

The northwest point at the confluence of the Missouri and Mississippi Rivers.

Flooding is the most costly and most deadly type of natural disaster in the United States . Missouri ranks second in flood mortality rates in the US with 76 deaths from 1992-2001. Missouri ranks fifth in flood damages with $3.65 billion dollar in damages for the same ten-year period. Yet there has been an acceleration of levee construction and development in the floodplains in and near Missouri cities, despite scientific evidence that flood control structures only serve to increase flood heights.

The pressure to develop the floodplains of St. Louis and St. Charles Counties has increased drastically as the St. Louis metropolitan area has expanded westward into St. Charles County . This is happening in spite of the 1993 flood which should have caused developers and local governments to realize the danger of developing in floodplains. Since 1993, more than 12,000 acres that flooded in the “Great Flood of ‘93” have been developed or are slated for new development. In the Chesterfield Valley alone, over $1 billion in commercial investment has been placed in areas that were under 10 feet of water in July of 1993. The city of Maryland Heights plans to heavily develop 4200 acres of Missouri River floodplain land once the Howard Bend Levee is raised to a purported 500-year level.

Howard Bend Levee construction in Maryland Heights , MO.

The St. Louis area is not alone. Near Kansas City , the Corps of Engineers recently awarded a contract to begin construction on the $80 million Riverside Levee along the Missouri River . The 5-mile long levee will purportedly protect 1300 acres and allow construction of a new mixed-use park containing industrial, commercial and retail space on 550 acres. This area flooded in 1993 resulting in over $63 million in damages.

Jefferson City is gathering funding for the local cost share of L-142 on the north side of the Missouri River across from the Capitol. L-142 is a federal levee that will be built at an unprecedented 1000-year level. Part of the area protected by L-142 and some of the footprint of the levee will cover land that was purchased using federal hazard mitigation funds after the 1993 and 1995 floods.

Properties purchased in the Hazard Mitigation Grant Program are subsequently deed restricted to allow only open space uses. Construction of a levee on such property is specifically prohibited by the Federal Emergency Management Agency (FEMA) regulations governing the program. However, political pressure from the Corps, Senators Bond and Ashcroft, and Missouri government officials convinced FEMA to allow construction of L-142 over mitigation land.

All of this floodplain development is likely at greater risk than the developers or the Corps of Engineers will admit. New scientific research suggests that large floods like those in 1993 and 1995 are becoming more frequent. The latest studies by geologists such as Dr. Nicholas Pinter of Southern Illinois University at Carbondale and Dr. Robert Criss of Washington University in St. Louis indicate that water levels seen on the lower Missouri and middle Mississippi Rivers during the 1993 flood could recur every 20 years. Their research implicates river engineering, including navigation structures and levees, as a likely cause of increased flood heights.

This figure from Robert E. Criss' 2002 paper "Rising Flood Stages on the Lower Missouri River " illustrates the increase in recurrence of high flood stages in the last 60 years. 

The Missouri Coalition for the Environment (MCE) has been working to preserve the natural value of Missouri ’s floodplains for over 30 years. Lawsuits filed by MCE resulted in a consent agreement forcing the Corps of Engineers to regulate navigable waters up primary tributaries to the ordinary high water mark. MCE was critical in the effort to prevent development of a sports multiplex in the Missouri River floodplain that would have moved the professional football and baseball stadiums out of downtown St. Louis .

More recently, MCE led the effort at the state level to stop the St. John’s Bayou/New Madrid Floodway project. This devastating project would close off the last area of the Mississippi floodplain that is still connected to the river. In the process it would destroy at least 20,000 acres of wetlands and disrupt the hydrological connection between Big Oak Tree State Park and the Mississippi River . Many state champion trees in the park would likely die as a result. Though the Missouri Department of Natural Resources denied water quality certification to the project in November 2002, this fight is far from over. MCE will continue to play a lead role in the effort to prevent this destructive project from ever being completed.

Cypress trees in Big Oak Tree State Park .
Photo courtesy Missouri Department of Natural Resources.

MCE has initiated a campaign to introduce and pass comprehensive floodplain management legislation in the Missouri legislature. A survey of floodplain management laws in Missouri and six other Midwestern states shows that Missouri lacks any jurisdiction over its floodplains and even prohibits local governments from denying development permits in the floodplains. A comprehensive state floodplain management program could discourage and prevent the most destructive and dangerous development projects and save taxpayers millions in future disaster relief.

MCE is working with a variety of other groups and government agencies to protect floodplains. MCE hosts quarterly meetings of the Floodplain Alliance – a group of local, regional and state level organizations and government agencies concerned about floodplains and river issues. The Floodplain Alliance allows non-profit advocacy groups to coordinate their efforts and keep an open dialogue with the government agencies charged with protecting natural resources.

In addition, MCE participates in the Water Resources Advisory Council (WRAC) that advises the East-West Gateway Coordinating Council on water issues in the St. Louis Region. MCE chairs the Floodplain Management Committee of the WRAC. The committee has focused on determining the cumulative effects of floodplain development on flood heights in the region and developing floodplain best management practices for local governments.

While MCE has fought hard to protect Missouri ’s floodplains, the interests pursuing development of this resource are well funded and tireless. We need your help to continue the fight to preserve the natural beauty and function of Missouri ’s floodplain resources. Check this site regularly for updates on specific issues and to find out about how you can help by writing a letter, attending a public hearing or supporting our efforts in other ways.

Thanks to the McKnight Foundation for financial support of MCE’s Floodplain Protection Project.