In many places in this immense flood zone in eastern North Carolina, an incredible stench fills the air as the bloated bodies of drowned hogs and immense piles of dead turkeys and chickens wait to be scooped into dump trucks and fed into incinerators. Molds already cover the walls of flooded buildings, like soft, lung-irritating moss. And residents are being warned not to toss lit matches or cigarettes, because the floodwaters are slick with swirls of escaped gasoline.

As the rivers left swollen by Hurricane Floyd have crested and slowly started receding, a new danger awaits officials and residents in this bedeviled region east of Interstate 95: a public and environmental health hazard that could last for months.

"We've basically got a witch's brew, from chemical releases, flooded wastewater treatment plants, flooded junkyards, flooded animal operations, just to name a few," said Don Reuter, a spokesman with the N.C. Department of Environmental and Natural Resources. "Everything that was on the land gets washed into the water -- fertilizers, oils, everything. From a number of fronts, we're very concerned about the safety of the people in the days ahead."

The problems include contaminated tap water that can cause diarrhea and other intestinal problems if ingested; hungry snakes driven from hiding places and angry fire ants floating atop logs and other debris; huge mosquito populations breeding disease in stagnant pools; and molds from damp walls, furniture and carpeting that can cause respiratory problems in even the healthiest people. Because the flooded streams and rivers eventually make their way to the delicate estuaries and on to the sea, the state's blue crabs, clams, shrimp and other edible marine life may be polluted as well, deflating the state's $1 billion fishing industry.

"About the only thing that may work in our favor," Reuter said, "is that there is so much water out there, maybe the dilution factor will come into play."

There is indeed much water out there. Many places in Nash, Duplin and Pitt counties, for example, look like huge lakes dotted with rooftops. So much that state and local officials have not even begun to assess the damages, already estimated at more than $1.3 billion.

Forty people have been counted dead, some from heart attacks as they tried to empty water from their homes or rescue others. Many drowned when their vehicles were swept away as they tried to travel deceptively flooded roads. At least 1,600 homes may be damaged beyond repair, according to the governor's office, and more than 10,000 people remain in emergency shelters, still stranded by high water.

The last thing people needed in this sodden region was more rain, but that is what they got Monday and today as Tropical Storm Harvey cut across Florida. At least an inch fell in many areas, but fears of widespread flash flooding apparently did not pan out. Clearing skies are expected for the next several days, giving officials and residents a chance to assess what needs to be done.

Although most of the dead farm animals remain underwater -- or unreachable because of impassable roads -- state agriculture and health officials are gearing up to begin disposing of the 100,000 hogs (on average weighing 250 pounds apiece), 500,000 turkeys and 2.4 million chickens.

Incineration had started near Trenton in Jones County, where officials were burning 3,000 to 4,000 pounds an hour. In all, four incinerators in Jones, Wayne and Duplin counties will run almost around the clock, said Joan Alford of the veterinary division of the N.C. Department of Agriculture. State and federal workers, farmers and volunteers will begin using front-end loaders to gather up the carcasses, load them into trucks and dump them into the 3,500-degree incinerators. Other animals may be buried.

"In recent memory, there has never been anything like this, the spread of what we have to do," said Andrea Ashby, a state agriculture spokeswoman.

Public health officials are concerned about everything from mud-slippery streets that may prompt falls to diseases such as tetanus and hepatitis A that can be caused by contact with contaminated waters.

"The public needs to think prevention," said David Rice, New Hanover County's health director. "We've heard that all our lives, but in this case, it is really true. We cannot stress this long enough: `Wash your hands, wash your hands, wash your hands.' "

But that, of course, begs the question of what to wash with. Bottled water is the obvious answer, since many private wells and public water systems have been breached, and dozens of wastewater treatment plants, including large facilities in Wilson, Goldsboro, Kinston and Tarboro, have released untreated waste into the mix. Boiling the water is an option, but is not recommended for pregnant women or children.

In Tarboro today, divers who went under to check out problems in the flooded downtown area received special treatment when they emerged: Clorox scrubs.

Bleach and other disinfectants will be valuable commodities once the cleanup begins. Public health officials recommend using a quarter of a cup of bleach per gallon of water to wash down floors and walls. They hope the state's high childhood immunization rates may cut down on illnesses spawned by the flood, but most local health agencies are offering free tetanus booster shots, just in case.

In many of the salvageable homes, water-saturated carpets, wall coverings and furniture will have to be tossed, even those that appear to be dry on the outside, because of powerful molds.

"When in doubt, toss it out," Rice said. But there will be many people, he added, who cannot afford to replace the items.

For North Carolina officials who have shepherded the state through 20 years of explosive growth -- and basked in its progressive new image -- the tasks seem enormous.

"We had made such great strides in addressing our water quality issues and we are very concerned this has set us back," said Reuter. "The stakes are much greater than they used to be. North Carolina has grown so much in the past 20 years, there is so much more out there to be affected. When you see communities like Tarboro, where everything has come to a halt, you realize this is an environmental catastrophe and an economic catastrophe. And for too many people, it is a personal catastrophe."

Staff writer Scott Wilson contributed to this report from Tarboro, N.C.