WASHINGTON - Sewage and chemicals are mixed into a potentially toxic bathtub soaking New Orleans, posing the threat of disease for residents forced to wade in Hurricane Katrina's floodwaters.
"Probably the more immediate health risk to the people is that whatever was in the sewer is in the water," said John Pardue, director of the Louisiana Water Resources Research Institute at Louisiana State University in Baton Rouge. "Whatever bacterial or viral diseases that people put into the system before the flooding is now in the water."
Meanwhile, scientists say they're alarmed by how much of the region's environmental defenses against future hurricanes and other big storms have become seriously compromised.
Officials with the U.S. Geological Survey who flew over the Gulf Coast from Florida to Louisiana said Thursday that most of the Chandeleur chain of barrier islands - the first line of storm defense for eastern Louisiana and western Mississippi - appears to be gone. What is usually a continuous line of dunes is now just marshy outcrops, said Ann Tihansky, a hydrologist with the survey. "It's unbelievable," she said, after reviewing the results of an aerial video survey.
"It just makes the coastline more and more susceptible because more of that storm surge can move further inland," said Glenn Guntenspergen, a U.S. Geological Survey landscape ecologist who has studied the effect of hurricanes on Gulf Coast ecosystems.
With the loss of the islands and wetlands that buffer the region, he said, "It becomes less and less likely for the systems to be able to recover from these kinds of storms. The systems as a whole are rapidly losing their ability to recover."
Along with the sewage in the floodwater is a witches' brew of chemicals from a variety of sources, including leaking fuels and oils from gas stations and submerged cars, paints and solvents from small businesses and household cleaners and pesticides from peoples' homes.
But the biggest chemical plants and refineries to the south and east of the city were spared a direct hit by the hurricane. If that had happened, breaches in large tanks and other industrial facilities might have spewed heavy petroleum, hydrocarbons and chlorine gas.
"From the perspective of chemical or environmental contamination, it could have been much worse. One advantage is that we have so much water in the city and that dilutes out the chemicals," Pardue said. "People shouldn't have an irrational fear of chemicals in the water. I'm more concerned about the viral and bacterial things. There's going to be a lot of gastrointestinal and public health issues."
Besides the broken sewage systems polluting the floodwaters, breached drinking water systems are no longer functioning.
Sam Coleman, a regional director for EPA's Superfund toxic waste division in Dallas, said he could not predict how long it would take to clean, disinfect and then test the hundreds of small community drinking water systems that no longer work because of the loss of power.
"Personally, I've never seen anything like this," he said. "No one has quite seen it this bad."