Development Rises on St. Louis Area Flood Plains

Miles and miles of bigger and stronger levees have been built along the Missouri and Mississippi Rivers since the deadly floods of 1993, and millions of dollars have been spent on drainage improvements.

Yet as the rush of water that caused the Missouri River to overflow its banks and submerge dozens of towns last week rolled toward St. Louis on Monday, attention was turned to a metropolitan region that since 1993 has seen runaway residential and commercial development in the rivers’ flood paths.

About 28,000 homes have been built and more than 6,000 acres of commercial and industrial space developed on land that was underwater in 1993, according to research by Nicholas Pinter, a geologist who studies the region at Southern Illinois University in Carbondale.

Building is happening on flood plains across Missouri, but most of the development is in the St. Louis area, and it is estimated to be worth more than $2.2 billion. Though scientists warn about the danger of such building, the Missouri government has subsidized some of it through tax financing for builders.

“No one has really looked at the cumulative effect,” said Timothy M. Kusky, a professor of natural sciences at St. Louis University, who calculates that there has been more development on the Missouri River flood plain in the years since 1993 than at any other time in the history of the region.

The good news for St. Louis right now is that forecasters say the two rivers will crest well below their 1993 levels by Tuesday, sparing the area significant flooding. But many scientists remain concerned that the effect of the new construction, should a levee break, could eventually be even more severe flooding.

Levees constrict a river’s path and raise its water level, which causes higher, faster flow. A flood plain, conversely, exists in nature to absorb a river’s overflow.

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