Katrina Floodwaters Less Toxic Than Predicted

Still, It Wasn't Safe for Drinking, Study Shows

Reviewed by Louise Chang, MD on October 12, 2005
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Oct. 12, 2005 -- The waters that flooded New Orleans after Hurricane Katrina were pretty nasty, but they may not have been as toxic as experts had feared.

That may be a comfort to the storm survivors and emergency workers who slogged through those waters.

Still, you wouldn't want to have drunk the floodwater, and fish in Lake Pontchartrain may not be in the clear.

That's according to a study in Environmental Science & Technology's online edition. It's a first look at Katrina's floodwaters in New Orleans.

The researchers included John Pardue, PhD, an environmental engineer and director of the Louisiana Water Resources Research Institute at Louisiana State University in Baton Rouge.

What Was in the Floodwaters?

The New Orleans floodwaters were found to contain:

  • Bacteria (most likely from fecal contamination in sewage).
  • Gasoline components (benzene, toluene, and ethylbenzene -- most likely from submerged vehicles).
  • Common compounds from household chemicals including aerosol paints and insecticides.
  • Metals such as lead, arsenic, and chromium.

The mix was not fit for drinking. But the levels of bacteria and most metals were not very different from typical New Orleans storm water runoff, write the researchers. However, the levels of lead and gasoline components were slightly more elevated.


In the days after Katrina struck, researchers braved the city in a flat-bottomed boat, gathering 38 samples of floodwater from the West End, Lakeview, and Tulane-Gravier areas of the city. Many storm survivors and first responders were exposed to floodwaters in those areas, the researchers note.

Floodwaters being pumped back into Lake Pontchartrain at the 17th Street drainage canal were also checked.

'Could Have Been a Lot Worse'

"What we had in New Orleans was basically a year's worth of storm water flowing through the city in only a few days," says Pardue in a news release.

"We still don't think the floodwaters were safe, but it could have been a lot worse. It was not the chemical catastrophe some had expected," he continues.

"What distinguishes Katrina floodwaters are their large volume and the human exposure to these pollutants that accompanied the flood rather than extremely elevated concentrations of toxic pollutants," write the researchers.

The presence of metals and low oxygen levels in the waters that were pumped into Lake Pontchartrain may endanger fish, so long-term monitoring should be done, note the researchers.

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SOURCES: Pardue, J. Environmental Science & Technology, Oct. 11, 2005; online edition. News release, American Chemical Society.

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