Flood thy neighbor: Who stays dry and who decides?

are intensifying, dumping more water into the Upper Mississippi basin. Researchers and regulators generally calculate future flood patterns based on a river’s past behavior. But climate change makes everything more unpredictable.

The Corps now considers climate change in some of its flood planning, but an Obama-era executive order that might have strengthened its approach was rescinded last year by President Donald Trump.

The Corps never updated its 1993 calculations or checked them for accuracy — not when the levee was finished in 2005, nor when the levee held back its first big flood in 2008 or after the larger, more recent floods. The Corps used widely available modeling software of the early 1990s. The technology’s ability to accurately model how rivers behave has significantly improved since then.

John Boeckmann, an engineer for the Corps’ St. Louis District and chief of its hydrologic engineering section, said he still stands by the Corps’ 1993 calculations. Any flooding coming from the levee is localized and “is not affecting other communities upstream,” he said. “We’re confident what was done then is sound science and good engineering.”

When ProPublica and Reveal asked the Corps whether it ever checks its predictions of levee-induced flooding against more recent data, a spokesman from agency headquarters in Washington said the “verification process that you describe is not a practice that (the Corps) uses.”

As a result, levees that are meant to last for decades, even a century, are built based on maps and modeling technology from another era.

“Thanks for the Water, Valley Park”
The Valley Park levee met its first test when floods tore through the Midwest in spring 2008. One bar owner told reporters that she was so confident in the new levee that she hadn’t bothered to pick up her computer off the floor.

“It’s a 100-year event, and it’s a 100-year levee,” Army Corps of Engineers Col. Lewis Setliff declared. “It got tested, and it passed.”

But upstream in Pacific, the mood was grim. More than 200 buildings flooded. Then-Mayor Herbert Adams urged federal