GREEN

Mississippi River Flooding Reaching Historic Levels

05/11/2011 08:45 pm ET | Updated Jul 11, 2011

In one of the worst cases of flooding since the Great Depression, the bulging, swollen Mississippi River is overflowing in record proportions, blanketing thousands of square miles across Arkansas, Tennessee and Mississippi, negatively impacting the environment, and causing billions of dollars in damage.

After weeks of intense rainfall, the water level is breaking records across Mississippi. In Natchez, Miss., the water now stands at 58.3 feet, shattering the 1937 watermark of 53.04 feet. And the National Weather Service says that the flooding is just getting started.

While residents scramble to reach higher ground, the rest of the country has focused on the economic and environmental impacts of this last round of severe weather, which comes in the wake the devastating tornadoes that swept the Southeast two weeks ago.

The water is flooding some of the most fertile areas in the country, so damages to agriculture alone could easily top $2 billion, according to estimates by economist John Michael Riley, a professor in the department of agricultural economics at Mississippi State University.

“Crop lost estimates are definitely around $800 million for Mississippi alone,” Riley said. To that $800 million, Riley added another $500 million in estimated losses in Arkansas, and several hundred million more caused by flooding in Louisiana, Missouri and farmland north of Memphis in Tennessee.

But agricultural losses could just be the tip of the iceberg.

“Homes and business are being damaged, and there are all the industries that feed into agriculture. There are going to be far reaching losses,” Riley said. “So $2 billion is probably just a starting point in terms of overall, everything put together.”

River casinos in Mississippi are also being closed, which could cost the state $12 million a month in state and local tax revenue, according to Jon Moen, chair of the economics department at the University of Mississippi.

While it is too early to estimate the economic impact of structural losses, Sally Williams from the Mississippi Development Authority said the overall cost will depend heavily on whether the levees ultimately hold.

“It totally depends on what areas might be affected,” Williams said. “The levees could breach and we could have more flooding as a result of that, but the levees haven’t been breached yet.” Even with the majority of the levees intact, about 1,300 homes in Memphis were affected, and between 600-800 homes in Mississippi may be at risk, said Moen.

The total damages of the Mississippi flood of 1927, known simply as the “Great Flood”, cost a total of $230 million -- the equivalent of $2.8 billion today -- although there was far less infrastructure and agriculture in place at the time.

In anticipation of increased flooding, health officials are quick to emphasize the obvious, but important, point: Stay away from the water for environmental reasons.

The river is slowly spreading across millions of acres of farmlands that contain pesticides, fertilizers and other chemicals. The sheer amount of water is diluting the concentration of these toxic chemicals, but the Mississippi State Department of Health still note that the water could carry disease, especially tetanus.

Increased levels of E. coli are also of concern, because the bacteria can be an indicator for harmful pathogens that may cause illness. The Tennessee Department of Environment and Conservation is monitoring the levels weekly. So far, the agency has found that the state’s lakes do not have dangerously elevated concentrations of E. coli, except in Cypress Creek, which has a history of pollution.

The long-term environmental impacts of the flooding are more unpredictable, both for the region and its citizens. The stream of river water pouring into the Gulf of Mexico is filled with nitrogen and phosphorus pollutants, and scientists are concerned that the increased concentration of these mineral nutrients in the Gulf could contribute to the growing ecological disturbance known as “the dead zone.”

The dead zone is a lifeless band of ocean water off the coast, larger than the state of Massachusetts, in which shrimp and fish are unable to survive due to the lack of available oxygen in the water. Scientists expect that historic amounts of water cascading down the Mississippi this spring could lead to one of the largest-ever dead zones this summer, which could stretch the already massive area all the way to the Texas coast.

Donald Boesch, President of the University of Maryland Center for Environmental Science, said the increased size of the dead zone was "clearly a record."

Because the dead zone leaves a vast swath of the water off the Louisiana coast uninhabitable for fish and other sea life, it has a direct impact on local fisheries. Shrimpers are hit hard in particular, because the dead zone has the largest effect on bottom feeders like shrimp and other crustaceans.

“The shrimpers have already had a hard time because of the oil spill last year,” said Eugene Turner, professor at the Coastal Ecology Institute at Louisiana State University. As the size of the dead zone increases, Turner projects that shrimpers will need to travel farther to find the sea life, meaning sustaining higher fuel costs.

“They’re on a marginal economic lifestyle as it is,” he said. “And now they’re getting hammered.”

Yet the long-term effects aren’t all negative, scientists stress. Historically, the region has relied on flooding to replenish the soil with nutrient-rich sediment.

“In muddy delta systems, mud is a good thing,” said Boesch. The installation of levees decreased the amount of flooding, which in turn meant the soil was replenished less frequently.

“The whole region is sinking, and if it doesn’t get nourishment it’ll dry out and break off, which is what’s happening,” Boesch said. “So, yes, flooding can muck up people’s houses, but it’s actually necessary and important.”

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