BATON ROUGE, La. — The potentially toxic brew of chemicals and human waste in the New Orleans floodwaters will have to be pumped into the Mississippi River or Lake Pontchartrain, raising the specter of an environmental disaster on the heels of Hurricane Katrina, experts say.

The dire need to rid the drowned city of water could trigger fish kills and poison the delicate wetlands near New Orleans and the Gulf of Mexico at the mouth of the Mississippi.

State and federal agencies have just begun water quality testing but environmental experts say the vile, stagnant chemical soup that sits in the streets of the city known as The Big Easy will contain traces of everything imaginable.

"Go home and identify all the chemicals in your house. It's a very long list," said Ivor van Heerden, head of a Louisiana State University center that studies the public health impacts of hurricanes.

"And that's just in a home. Imagine what's in an industrial plant," he said. "Or a sewage plant."

Gasoline, diesel, anti-freeze, bleach, human waste, acids, alcohols and a host of other substances must be washed out of homes, factories, refineries, hospitals and other buildings.

In Metairie, east of New Orleans, the floodwater is tea-colored, murky and smells of burnt sulfur. A thin film of oil is visible in the water.

Those who have waded into it say they could see only about 1 to 2 inches into the depths and that there was significant debris on and below the surface.

Experts said the longer water sat in the streets, the greater the chance gasoline and chemical tanks -- as well as common containers holding anything from bleach to shampoo -- would rupture.

Officials have said it may take up to 80 days to clear the water from New Orleans and surrounding parishes.

Mike McDaniel, the secretary of Louisiana's Department of Environmental Quality, said it was too early to call the water "toxic."

"I'm saying that's a little bit exaggerated," he told reporters during a briefing in Baton Rouge. "To say it's toxic, it sounds like instant death walking in it. Let's get some better data."

Analysts have already found bacteria in the water and traces of pesticides and more dangerous pollutants, he said.

How much water New Orleans holds is open to question.

Van Heerden estimates it is billions of gallons. LSU researchers will use satellite imagery and computer modeling to get a better fix on the quantity.

Bio-remediation -- cleaning up the water -- would require the time and expense of constructing huge storage facilities, considered an impossibility, especially with the public clamor to get the water out quickly, he said.

SECOND DISASTER?

McDaniel said there was no choice but to pump it into Lake Pontchartrain or the Mississippi. The river flows into the Gulf of Mexico, a key maritime spawning ground.

"We have to get the water out of the city or the nightmare gets worse," he said. "Right now the priority is on saving lives."

The result could be a second wave of disaster for southern Louisiana, said Harold Zeliger, a Florida-based chemical toxicologist and water quality consultant.

"In effect, it's going to kill everything in those waters," he said.

The water will leave behind more trouble -- a city filled with mold, some of it toxic, the experts said. After other floods, researchers found many buildings had to be stripped back to concrete, or razed.

"If you have a building half full of water, everything above the water is growing mold. When it dries out, the rest grows mold," Zeliger said. "Most of the buildings will have to be destroyed."

(Additional reporting by Paul Simao in New Orleans)

Source: Reuters