Louisville’s Metropolitan Sewer District estimates it has released about four billion gallons of stormwater and raw sewage into the Ohio River and Beargrass Creek over the last five days while managing the deluge from city’s largest river flooding since 1997.

The city’s wastewater treatment plants are working at max capacity to treat as much water as possible before discharging it into waterways like the Ohio River. But with an estimated 40 billion gallons of rainfall in the last week, there is only so much the city can do, said Brian Bingham, MSD chief of operations.

“We had about 1.6 billion gallons of water go through our treatment plants over the five-day period,” said Bingham.

Bingham said about 5 to 10 percent of the untreated water contains human waste, which can cause infections and illness.

Floodwater also poses a variety of other health risks, even as it recedes. Pesticides, gasoline, asbestos and floating propane tanks are just a few of the possible hazards swimming among the debris, according to city and state officials.

Samantha Spicer of Valley Station said she saw floating furniture, trees, clothes and downed power lines while kayaking with her husband Cody through floodwater in West Point on Monday.

In some areas, “we picked up a real strong smell of gasoline,” she said. As for how high the water was, Spicer said she paddled alongside the top of a basketball hoop at a local park.

“We were touching the top of them,” she said.

Lees Lane, a 112-acre former federal Superfund site that was a repository for toxic chemicals south of Rubbertown, also received a couple feet of water as a result of the weather.

Bingham said he doesn’t believe the water will seep into the landfill. The flooding is already beginning to recede, he said.

Matt Rhodes with the Louisville Metro Department of Public Health and Wellness said there are few long-term health effects from chemicals once the water recedes. However, people should wear protective equipment when coming in contact with floodwater and cleaning out their homes, he said.

City officials are warning residents to avoid wading into flooded areas and waterways until at least next week.

While the vast majority of the water discharged into county waterways is allowed under federal permits, Bingham estimates 100 million gallons has also been illegally discharged. That was from the city’s sanitary sewer system, which provides wastewater treatment to many of the suburbs surrounding Louisville.

“We’re not happy with everything that’s occurred out there, obviously, but it has been a monumental storm event and the most important thing is for people to avoid contact and to know that we are working to continue to make things better,” Bingham said.

This story has been updated.

Ryan Van Velzer is WFPL's Energy and Environment reporter.