The first round of testing by the Environmental Protection Agency (search) has found that the floodwaters in New Orleans contain levels of sewage-related bacteria that are at least 10 times higher than acceptable safety limits, federal officials said Wednesday.

The results came as no surprise to health officials who have been warning about the toxicity of the floodwaters since Hurricane Katrina (search) first ravaged the Gulf Coast. Though officials have been warning that the flood water is too contaminated to drink since the first days following the storm, the EPA said Wednesday that even walking in the water posed serious health risks.

Rescue workers and residents remaining in the city were urged to take precautions to avoid getting the water on their skin — especially into cuts or other open wounds — much less in their mouths.

"Human contact with the floodwater should be avoided as much as possible," said EPA Administrator Stephen L. Johnson (search).

The filmy, foul-smelling water has actually caught fire in some places, due to gas, fuel and chemical leaks, FOX News Adam Housely reported Thursday. Rescue workers continue to find and remove corpses that have been floating in the water for as long as a week, and officials have prepared 25,000 body bags in preparation of a staggering death toll.

With local officials still struggling to convince a small group of residents refusing to evacuate New Orleans to leave the city, Dr. Julie Gerberding, director of the Centers for Disease Control and Prevention, said health hazards from the water make it imperative that remaining residents comply with evacuation orders.

"If you haven't left the city yet, you must do so," she said.

A large-scale break-out of infectious disease has yet to materialize, but five deaths at shelters in Texas and Mississippi have been attributed to open sores becoming infected by the water.

Meanwhile, Vice President Dick Cheney was dispatched to the Gulf Coast Thursday charged with cutting through the bureacracy that is blocking volunteer doctors from treating patients desperate for care. Many medical professionals trying to help Katrina victims have complained that red tape was preventing them from obtaining the necessary permission to treat patients at the shelters.

Contaminated Water

Also found were elevated levels of brain-harming lead, a risk if people, particularly children, were to drink the water, something residents have been told to avoid since Hurricane Katrina struck.

The first tests for more than 100 chemicals and other pollutants so far turned up elevated levels only of E. coli and other coliform bacteria — markers for sewage contamination — and lead.

But, "we don't know what else is contained in that water," Johnson warned.

The first testing was done on water from residential neighborhoods, not industrial sites where other toxic contaminants may lurk. Moreover, oil is in the water, and it's likely that chemicals such as asbestos will be in debris from older buildings, he said.

Federal health officials stressed that rescue workers should wear protective clothing and gloves before entering flooded areas, and be careful not to splash the dirty water into their faces. Find clean water and soap to wash exposed skin as soon as possible.

"Always, always, always wash hands before eating," Gerberding stressed.

Symptoms of E. coli ingestion are vomiting, diarrhea, stomach pain and fever; anyone with those symptoms, or who has open wounds exposed to tainted water, should seek medical attention.

Louisiana's state epidemiologist, Raoult Ratard, agreed that it's not a good idea to wade in the water for hours or drink it, but expressed concern that exaggerating the danger could scare rescue workers.

"The water is not safe, but the water is also not extremely dangerous," he said. "The best decontamination is a shower with soap and water."

Wednesday's initial focus was on standing floodwater, but more than 1,000 drinking water systems in Mississippi, Louisiana and Alabama were affected by the hurricane. EPA testing is going on in the other states, too, and how quickly drinking water can be restored in part depends on the degree of contamination in water supplies those systems treat.

Each water-treatment plant will have to adjust levels of chlorine, filtration and other treatments to eliminate pathogens, such as E. coli bacteria or the parasite cryptosporidium, says water quality expert Charles O'Melia of Johns Hopkins University.

If chemicals are in water supplies as well, it's possible activated carbon could soak them up, he said; routine treatment would remove the carbon.

Many hurricane-stricken areas have issued boil-water alerts, and boiling will kill bacteria and parasites, O'Melia said. The CDC recommends a rolling boil for one minute; some health experts recommend the additional step of running the water through coffee filters.

For people who can't boil water, adding chlorine from unscented household bleach will kill bacteria, but not cryptosporidium, a diarrhea-causing parasite dangerous to people with weak immune systems, O'Melia cautioned. The CDC recommends one-eighth teaspoon of bleach per gallon of clear water, one-fourth teaspoon if the water is cloudy; let it stand for 30 minutes before drinking.

Also Wednesday, federal health officials said evacuees still in shelters later this fall will be among the first people vaccinated against the flu because of the risk that highly contagious influenza could sweep through the crowded facilities. Manufacturer Sanofi-Pasteur is making 200,000 of the first flu shots available to those evacuees, Gerberding said.