Summary
Highlights
Eureka, Missouri, experiences repeated catastrophic floods, while just 12 miles downstream, Valley Park remains dry due to a large levee. This levee, funded by Valley Park's ability to pay, has been suspected of worsening flooding in neighboring towns like Eureka and Fenton, raising the question of whether levees protect one town at the expense of others, especially those that cannot afford similar infrastructure.
Levees have been a default for flood control for centuries, with around 100,000 miles across the US. However, as early as 1852, civil engineer Charles Ellet Jr. warned that levees confine rivers, causing water to rise higher and flow faster, and encouraging a "false security." Despite these warnings, local entities largely funded and constructed levees, leading to a system where wealthier communities built taller protections while less fortunate neighbors suffered the consequences.
A fluid mechanics lab at the University of Minnesota demonstrates how levees impact flood scenarios. Without levees, rivers overflow and spread across floodplains, creating important wetland habitats. Levees cut rivers off from this land, destroying floodplains and narrowing the river, causing water to flow faster and higher. This creates a bottleneck that leads to additional flooding upstream. The model also shows that when one side builds higher levees, it significantly disadvantages the side with lower or no levees, leading to unequal flooding.
An alternative solution is building "setback levees" farther back from rivers, allowing rivers to expand and create wetlands, thereby easing flooding on both sides. This approach is common in other parts of the world, like Holland, but not in the U.S. The Army Corps of Engineers, a federal agency, is tasked with regulating some levees, but their engineering predictions don't always match reality. The Valley Park levee is an example where the original impact assessment failed to account for subsequent regional growth, potentially contributing to the two worst floods in the region's history outside Valley Park since its completion.
Research indicates that levees push flooding onto surrounding communities with lower or no levees, with studies showing increases of over five feet in water levels. As climate change progresses and cities push for higher levees, flooding is expected to worsen, especially along the heavily leveed Mississippi River. Many levees have been illegally raised, exacerbating the problem. The current regulatory system for levees is broken, as the science overwhelmingly shows that building taller levees makes flooding worse in the long term, passing problems upstream rather than solving them.