Veronica Tate knew from the stench that sewage was among the 8 feet of water that swamped the basement of her ranch-style home after the nearby Meramec River overflowed. The larger concern for residents of her suburban St. Louis neighborhood is the unknown of what else the noxious blend might have contained.

In this aerial photo, people use a canoe to navigate a flooded street, Thursday, Dec. 31, 2015, in Arnold, Mo. (AP Photo/Jeff Roberson)

"It came up through the sewers, I guess," Tate, a customer service representative for an insurance company, said of last week's flooding.  "When you get down there and look at it, there's a smell. There's an odor."

Wastewater was a certainty in her Arnold neighborhood, given that two nearby treatment plants failed when the Meramec flooded in record fashion after days of unrelenting rain. The inundation spewed tens of millions of gallons of untreated human waste on a path toward the Mississippi River and an unavoidable, southward trek to the Gulf of Mexico. Those plants remained offline Tuesday.

But the floodwaters also could include such things as fertilizers, pesticides and herbicides washed away from farmland, not to mention livestock waste, industrial chemicals, dead animals, gasoline from convenience stores and toxins from railroad tracks.

Much of the pollution eases its way into the Meramec and other rivers that feed into the Mississippi, for many communities the source of drinking water.

By Tuesday, the inundation from last week's flooding had been cleared from Tate's home in Arnold, and her basement will soon be gutted to contain another health concern -- dangerous mold that can infest soaked sheet rock, flooring and furniture. There's not yet an official tally of homes and businesses in the area that sustained damage.

Even sandbags, touted as last-ditch defenders against floodwaters, pose a health risk because inundations turn them into mountains of smelly, polluted sacks that often are destined for landfills, along with flood-ruined household items such as sodden flooring, furniture and appliances. Well over a million sandbags were put to use in Missouri and Illinois since Christmas Day, according to governmental figures.

With each bout of broad flooding, such pollution threatens to sicken anyone who wades into the water, prompting health officials to urge affected residents -- and even reporters -- to proactively get tetanus shots if they're unable to stay away from direct contact with the floodwaters.

Floodwaters may contain more than 100 types of disease-causing bacteria, according to a 2012 report by the Union of Concerned Scientists. And while the frequency of waterborne illnesses due to flooding is not immediately clear, the Centers for Disease Control and Prevention warns that direct contact to inundations and the fecal bacteria they may contain could cause gastrointestinal illness or other infections.

In Chester, Illinois, roughly 60 miles southeast from St. Louis, the Mississippi rolling by is the 8,600-resident city's sole supplier of drinking water, Chester water plant supervisor Tim Crow said Tuesday. During inundations that could impact the Mississippi and ultimately Chester, Crow said he relies on guidance from the Illinois Environmental Protection Agency.

But Crow insists the city's water supply remains safe and exceeds state environmental standards, noting that sewage in the engorged Mississippi "is so diluted when it gets to us."

"We monitor it, but at this time there's no level of concern," he said at the water plant, which treats roughly 1.5 million gallons of water a day during the winter. "We haven't had any issues whatsoever."

The rains that caused this winter's flood, blamed already for at least 25 deaths in Missouri and Illinois and damage to hundreds of homes and businesses, ended a week ago. But the water continued rising Tuesday in southern Missouri and Illinois. Several other states along the Mississippi still were bracing for the crest.

(Copyright 2016 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.)


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