NEW ORLEANS — Despite the stench — and the pair of pants, bottle of hair spray and plastic oil cans that float by — Kenneth Economy wades barefoot into New Orleans' fetid brown floodwater.

He has no choice, like so many locals trying to right this wronged city. He is trying to restart the motor of a flat-bottomed boat as he and friends work to rescue people and animals from their neighborhood. Those floodwaters, which have already destroyed an estimated 140,000 to 160,000 homes, now pose a new challenge.

As engineers began pumping out the Big Easy, creating small but visible wakes of water behind street signs and tree trunks, the water they're moving carries a volatile mix of everything imaginable — from household paints, deodorants and old car batteries to railroad tank cars, sewage treatment plants and landfills. While state officials stop short of calling it a toxic soup, at least so far, federal environmental officials call it catastrophic.

Because of the risk of disease from the putrid, sewage-laden floodwaters, police and soldiers — using the unmistakable threat of force — went house to house Wednesday, trying to coax the last 10,000 or so stubborn holdouts to leave the city.

"A large group of young armed men armed with M-16s just arrived at my door and told me that I have to leave," said Patrick McCarty, who owns several buildings and lives in one of them in the city's Lower Garden District. "While not saying they would arrest you, the inference is clear."

Mayor Ray Nagin ordered law officers and the military late Tuesday to evacuate all holdouts — by force if necessary. He warned that the combination of fetid water, fires and natural gas leaks after Hurricane Katrina made it too dangerous to stay.

In fact, the first government tests confirmed Wednesday that the amount of sewage-related bacteria in the floodwaters is at least 10 times higher than acceptable safety levels. Dr. Julie Gerberding, chief of the Centers for Disease Control and Prevention, warned stragglers not to even touch the water and pleaded: "If you haven't left the city yet, you must do so."

There were no reports Wednesday of anyone being removed by force. And it was not clear how the order would be carried out.

Active-military troops said they had no plans to use force. National Guard officers said they do not take orders from the mayor. And even the police said they were not ready to use force just yet. It appeared that the mere threat of force would be the first option.