NEW ORLEANS—It all lies submerged in a toxic gumbo: grease and gas from up to 350,000 vehicles; raw sewage; bleach and cleansers from the pantries of 160,000 flood-damaged homes; and, authorities fear, contaminants from damaged chemical plants and refineries.
Olive-colored like Army fatigues, the brew that covers New Orleans is brightened by rainbow petroleum slicks. It stinks of sulfur and rot.
Only when the waters recede will scientists begin to get a taste of the extent of the environmental damage. Then they have to figure out how to clean it up.
"You just cannot understand the magnitude of what we're facing," said Jean Kelly, spokeswoman for the Louisiana Department of Environmental Quality.
About 20 million tons of debris will be left behind, much of it coated with potentially toxic muck. State environmental officials are scrambling to find safe ways to burn the debris and to junk the vehicles.
Some scientists caution that the receding floodwaters could leave polluted "hotspots" in the soil that would need to be cleaned up or capped before houses could be rebuilt. Nobody has yet offered an estimate of the staggering costs.
The state DEQ and the U.S. Environmental Protection Agency took 100 samples of the floodwaters last week. The agencies released test results showing dangerous levels of bacteria. They also detected the presence of heavy metals and toxic chemicals, but results of six of those samples released Sunday night showed readings within federal limits. Lead, however, was 56 times above the federal limit at one site.
In a statement, Louisiana DEQ said, without elaborating, that "very low levels" of toxics were found in the samples tested Sept. 4-5. Water sampling is ongoing, and the state is drawing up plans for extensive soil tests to begin when the city is dry.
Still, regulators and other scientists acknowledge that the full extent of the environmental devastation from Katrina is not yet known.
In addition, New Orleans and its surrounding parishes host 66 chemical plants, petroleum refineries and petroleum bulk-storage facilities that contain 878 different chemical combinations, according to the national Toxic Release Inventory, which tracks facilities that release toxic chemicals. Environmental regulators are checking on them by air and on the ground where possible; on Sunday, the state DEQ asked railroad companies for information on the contents of scores of overturned cars.
Three oil spills occurred on the Mississippi River below the city, but state officials reported they have been contained.
The millions of gallons of water being pumped from the city into Lake Pontchartrain bring their own environmental concerns of contamination. And, because the water is low in dissolved oxygen, wildlife officials expect fish kills.
The brackish, 630-square-mile lake is a breeding ground for marine life and birds, including a refuge for the rare sandhill crane. Its drainage basin covers 20 percent of Louisiana, ranging from cypress swamps to saltwater marshes near the Gulf of Mexico.
"The wonderful thing about nature is its resilience," state DEQ Secretary Mike McDaniel, a biologist, said at a news briefing last week. "The bacterial contaminants will not last a long time in the lake. ... The organic material will degrade with natural processes. Metals will fall and probably be captured with the sediments."
But in the city itself, questions about contamination could haunt rebuilding efforts.
"What we're talking about are hidden hazards," said Sylvia Lowrance, a former director of the EPA's program regulating industrial toxic waste. "You don't see them, you may not feel the effects for a year, two years, 20 years. And that's what we have to worry about."
She and other independent scientists say that environmental agencies must set up an extensive monitoring regimen and proceed slowly to reopen the city.
"There will be a need to assess ... neighborhood by neighborhood, water system by water system," said Lynn R. Goldman, professor at the Bloomberg School of Public Health at Johns Hopkins University. "Some areas may come on line very quickly, and there are others were it may take a very long time before the `all clear' to rebuild."
But now, water still stands in the lowest-lying areas of New Orleans, and people remain to be evacuated. Late last week, a military Humvee was parked on an Interstate 10 overpass, blasting a warning through loudspeakers to people still stranded in the Seventh Ward: "Do Not Go in the Water!" Soldiers attempting to convince the holdouts to leave repeatedly warn of the dangers from bacteria and toxic chemicals.
On Monday, authorities were to begin spraying pesticides over parts of the city to stop disease-bearing mosquitoes from hatching.
Rescue workers have reported nasty skin rashes and some infections of existing cuts from working in the water, as did some members of an engineering battalion of the Louisiana National Guard shoveling muck from the drying streets in St. Bernard Parish. Many soldiers wear gloves as they ply the waters, but their main precaution, Flick said, is to avoid the water.
"It's deadly," said Sgt. Michael Flick, of the Ohio National Guard, who was searching for bodies by boat in the eastern New Orleans. "You just can't touch this water."
(c) 2005, Knight Ridder/Tribune Information Services.
Need to map