Harvey flood flows with sewage and chemicals

I would be concerned about what’s in the water that people will be drinking.

Gary Norman

HOUSTON: 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.

Houston already was notorious for sewer overflows following rainstorms.

Now the system, with 40 wastewater treatment plants across the far-flung metropolis, faces an unprecedented challenge.

State officials said several dozen sewer overflows had been reported in areas affected by the hurricane, including Corpus Christi.

Private septic systems in rural areas could fail as well.

Also stirred into the noxious brew are spilled fuel, runoff from waste sites, lawn pesticides and pollutants from the region’s many petroleum refineries and chemical plants.

The US Environmental Protection Agency reported on Sunday that of the 2,300 water systems contacted by federal and state regulators, 1,514 were fully operational.

More than 160 systems issued notices advising people to boil water before drinking it, and 50 were shut down.

The public works department in Houston, the nation’s fourth largest city, said its water was safe.

The system has not experienced the kind of pressure drop that makes it easier for contaminants to slip into the system and is usually the reason for a boil-water order, spokesman Gary Norman said.

In a statement Thursday, federal and state environmental officials said their primary concerns were the availability of healthy drinking water and “ensuring wastewater systems are being monitored, tested for safety and managed appropriately”.

About 85% of Houston’s drinking water is drawn from surface sources – rivers and reservoirs, said Robin Autenrieth, head of Texas A&M University’s civil engineering department.

The rest comes from the city’s 107 groundwater wells.

“I would be concerned about what’s in the water that people will be drinking,” she said.

The city met federal and state drinking water standards as well as requirements for monitoring and reporting, said Andrew Keese, spokesman for the Texas Commission on Environmental Quality.

Keeping it that way will require stepped-up chemical treatments because of the flooding, Norman said.

It’s prudent to pump more chlorine and other disinfectants into drinking water systems emergencies like this, to prevent outbreaks of diseases such as cholera and dysentery, said David Andrews, senior scientist with the Environmental Working Group, an advocacy organisation.

But doing so poses its own risks, he said. There’s often more organic matter – sewage, plants, farm runoff – in reservoirs or other freshwater sources during heavy rains.

When chlorine reacts with those substances, it forms chemicals called trihalomethanes, which can boost the risk of cancer and miscarriages, Andrews said.

“Right now it’s a tough time to deal with just trying to clean the water up,” he said.

“But we should do better at keeping contamination out of source water in the first place.”