Storm clouds roll in over flooded farmland April 27, 2011 near Metropolis, Ill.
Storm clouds roll in over flooded farmland April 27, 2011 near Metropolis, Ill. - 
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Tess Vigeland: The U.S. Army Corps of Engineers blasted another hole in a Missouri levee this afternoon. It was the second attempt this week to control the ever-swelling Mississippi River. Flooding already forced thousands of people out of their homes and destroyed valuable farmland. And the worst damage may still be a week or two and potentially hundreds of miles away.

From the Marketplace Sustainability Desk, Adriene Hill reports.

Adriene Hill: The Mississippi River continues to challenge flood records, racking up major losses.

Jim Pogue: One that we're acutely aware of is the damage to the farmland that was in the floodway and the crops that those people have lost and there were people with homes in there.

Jim Pogue from the U.S. Army Corp of Engineers expects more damage as the river rolls south over the next few weeks. He says there are other less obvious costs, like the money communities shell out as water heads their way.

Pogue: Everything from extensive overtime for their employees, all of the equipment and supplies they need to fight their own battles.

Jeff Huffman: It's just an ocean out there right now.

Jeff Huffman is the county executive in Tipton County, Tenn., along the Mississippi.

Huffman: We don't know what the costs are because the river is still rising, so a lot of the damage is underwater, we just can't see it.

Other costs are clearer; some shipping channels have shut down. And then there's the issue of what happens when all that water, loaded with fertilizer from flooded fields, gets to the Gulf of Mexico. That fertilizer causes a "Dead Zone" where there's too little oxygen in the water.

Don Boesch heads the University of Maryland Center for Environmental Science.

Don Boesch: If there's no oxygen on the bottom over very large areas, then there's no fish and shrimp and shellfish and the like that can live there.

This flood will cause the Dead Zone to expand -- an environmental cost that's hard to put a price tag on. And a predictable loss from a very unpredictable flood.

I'm Adriene Hill for Marketplace.

Follow Adriene Hill at @adrienehill