Harvey's Floodwaters Mix a Foul Brew of Sewage, Chemicals

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Harvey's Floodwaters Mix a Foul Brew of Sewage, Chemicals

Harvey's filthy floodwaters pose significant dangers to human safety and the environment even after water levels drop far enough that Southeast Texas residents no longer fear for their lives, according to experts.

Sewage plants are particularly vulnerable during severe storms because they are located near waterways into which they can discharge treated water. When they are flooded, raw or partially treated sewage can spill from pipes, open-air basins and tanks.

A report by the nonprofit research group Climate Central said more than 10 billion gallons of sewage was released along the East Coast during Superstorm Sandy.

The Houston Chronicle reported last year that Houston averages more than 800 sewage overflows a year and is negotiating an agreement with the EPA that would require system improvements.

Norman said Houston didn't have a running tally of overflows during Harvey.

"Anytime you have wet weather of this magnitude, there's going to be a certain amount of sanitary sewage that escapes the system," he said. "That's one reason why we advise people to stay out of floodwaters."

A Texas A&M analysis of floodwater samples from the Houston area revealed levels of E. coli — bacteria that signal the presence of fecal matter — 125 times higher than is safe for swimming. Even wading through such tainted water could cause infections and sickness, said Terry Gentry, an associate professor and specialist in detecting tiny disease-producing organisms.

"Precautions should be taken by anyone involved in cleanup activities or any others who may be exposed to floodwaters," said a statement from the U.S. Environmental Protection Agency and the state environmental quality commission.

They said they were developing a plan to sample residential wells.

Hazards will remain as waters gradually recede. Puddles, tires and other spots for standing water will attract mosquitoes, which can spread viruses like West Nile and Zika, Autenrieth said.

Much of the dirty water will flow through rivers, creeks and bayous into Galveston Bay, renowned for its oyster reefs, abundant wildlife and seagrass meadows. Officials will need to monitor shellfish for signs of bacterial contamination, said Doug Rader, chief ocean scientist for the Environmental Defense Fund.

The waters also may be rich with nitrogen and phosphorus, which feed algae blooms. When algae die and rot, oxygen gets sucked from the water, creating "dead zones" where large numbers of fish can suffocate.

"You have a potential for localized dead zones in Galveston Bay for months or maybe even longer," Rader said.

The bay opens into the Gulf of Mexico, where a gigantic dead zone forms in summer, powered by nutrients from the Mississippi River. This year's was the largest on record, said oceanographer Nancy Rabalais of Louisiana State University.

Ironically, Hurricane Harvey may have done the environment at least one favor by churning the Gulf's waters and sending an influx of oxygen from the surface to the depths. "A temporary silver lining," Rabalais said.


FILE - In this Aug. 31, 2017 file photo, Alejandra Castillo takes a break from carrying water-soaked items out of her family's home after flood waters receded in Houston. Experts say Harvey’s filthy floodwaters pose significant dangers to human safety and the environment that will remain even after levels drop far enough that southeastern Texas residents no longer fear for their lives. (AP Photo/Charlie Riedel, File)

FILE - In this Aug. 29, 2017 file photo, Steven Hathaway searches for people to help in an apartment complex in Kingwood, Texas. Authorities say standing water will contain untreated sewage, along with spilled fuel and toxic waste. They’re urging residents to stay out of it when possible. (AP Photo/Gregory Bull, File)


FILE - In this Aug. 29, 2017, file photo, homes are surrounded by floodwaters from Tropical Storm Harvey in Spring, Texas. Harvey's filthy floodwaters pose significant dangers to human safety and the environment that will remain even after levels drop far enough that southeastern Texas residents no longer fear for their lives. Now its system faces an unprecedented challenge. Authorities say standing water will contain untreated sewage, along with spilled fuel and toxic waste. They're urging residents to stay out of it when possible. (AP Photo/David J. Phillip, File)
 

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