Midwest flooding: What's at stake in plan to blast open Missouri levee

As several rivers across Midwest and Great Plains are set to crest, a federal judge in Cape Girardeau, Mo., has given the US Army Corps of Engineers the green light to blast openings in a levee along the Mississippi River to ease the flood risk to cities and towns downstream.

The approach highlights a tool that hydrologists and environmental groups have advocated for years to reduce long-term flood risks: removing levees at strategic locations to allow floodwaters to spread into a river's flood plain.

It's a strategy being adopted elsewhere, notably in the Netherlands. Its advocates say it not only relieves stress on the remaining levees by lowering flood heights upstream and downstream, but it could also reduce the amount of soil and nutrients spring floods flush into the Gulf of Mexico. Researchers point to the nutrient runoff as the culprit behind a dead zone that builds each year off the Louisiana coast.

But the notion runs afoul of residents – including farmers who work the fertile flood plains – who see the levees as sentinels protecting their homes, farms, and businesses.

"The big challenge to doing this is the fact that these flood plains are privately owned. People have made significant investments, including generations of families' time, turning them into productive farms," says Jeffrey Opperman, an ecologist and a senior adviser to The Nature Conservancy, which is testing the concept along the Ouachita River, a Mississippi River tributary, in northern Louisiana.

Any successful approach, he says, must be "very consistent with private-property rights."

The Corps has yet to decide if it will go ahead with the plan. But its preparations for routing water onto the flood plain on the west bank of the Mississippi between Cairo, Ill., and New Madrid, Mo., highlights the challenges.

The Missouri plan

Spring snowmelt from record winter snows in the northern US are coursing down the Mississippi, while the storm system that devastated the South brought heavy rain to an already saturated Ohio Valley. This is feeding into the Ohio River, which meets the Mississippi at Cairo.

Ordinarily, during peak flows, the Ohio River – which also receives flow from the Tennessee River – sends roughly 10 times more water into the Mississippi River than the Mississippi above the junction provides. This year's snowmelt and storms have only added to that influx.

At the center of the debate is the Bird Point–New Madrid Floodway, a 130,000 acre patch of farmed river bottom designed as a flood-control tool. The floodway is one of three located along the lower Mississippi river. They were established after a Mississippi flood in 1927 killed nearly 250 people across 10 states, an acknowledgment that under severe conditions, levees alone were unlikely to keep floodwaters at manageable levels.

The floodway is flood-plain land bounded by two levees that form essentially a giant tub, with an open outlet at the southern end. Already, rising floodwaters near New Madrid have started to back into the tub from its "drain," according to residents.

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