The state has received reports of more than 268 million gallons of sewage that spilled onto roads and into water around Florida so far this year and nearly 95 percent of it happened in Pinellas County during Hurricane Hermine.
St. Petersburg was the biggest offender, releasing 93 million gallons of wastewater into Tampa Bay. Soon after, water near the downtown beaches tested high for indicators of organisms that cause disease
After the storm, the state and the city of St. Petersburg began testing water around downtown and determined it was unsafe. Crews put up yellow signs along the shore, warning swimmers to stay out.
They found dangerous levels of fecal coliform and enterococci, two bacteria indicating disease-causing organisms were in the water.
These organisms could carry the risk of gastrointestinal illness or something more serious. Valerie Harwood, a biologist at the University of South Florida, says certain people are at greater risk.
“Children, elderly people, anybody who's immunocompromised, these are the people we worry about most being exposed to these types of bacteria,” Harwood said.
How risky? No one knows because the tests done by the city and state don't say what kinds of pathogens are in the water.
Harwood says more specific testing can be done. But it's more complicated and expensive.
"If we really want to know what's being released in the water that can potentially harm us then we need to do more thorough testing and actually be testing for pathogens as well as these fecal indicator bacteria," Harwood said.
Bacteria resistant to antibiotics is what scientists are most worried about. Two years ago, when St. Petersburg had a similar release during a storm, Harwood and her colleagues found a strain of antibiotic resistant bacteria in the runoff.
Last week, Harwood's doctoral student Suzanne Young was gathering waters samples for her own research. At a park in the city's Old Southeast neighborhood, she pulled on gloves and waterproof boots before wading in for samples.
"I have two liters of water that I'll take back to the lab and we'll filter to detect the fecal indicator bacteria," Young said.
Young is testing for the same bacteria as the city and state. But she's also testing for antibiotic resistant bacteria. She's hoping to share the results soon.
John Palenchar is environmental compliance manager for the City of St. Petersburg. He says the city's lab isn't set up to test for bacteria resistant to antibiotics or other pathogens. And outsourcing the tests could cost many hundred times more than the city now spends.
Besides, he says, the better tests still may not be enough because state and federal health agencies haven't set standards for safe levels of antibiotic resistant bacteria.
"Even if we were able to determine a concentration of a specific pathogen we could just report a present or an absent result," Palenchar said. "We could not make any health risk assessment like we can with those accepted indicators."
Large bodies of water like Tampa Bay aren't the only place where people should worry about contaminated stormwater.
During storms, wastewater can back up into your front yard ... and streets may flood and manholes could overflow. Hurricane Hermine led to Millions of gallons of sewage flowing into neighborhoods across the Tampa Bay area.
And those floodwaters are rarely tested.
They could be even more dangerous, says Mary Yeargan, district director for the Department of Environmental Protection.
"If you see something bubbling up out of the street, don't let your kids play in it," Yeargan said. "People should not be thinking this is like going to the swimming pool or the beach. Stormwater is not clean and they should not go out in it."
Yeargan's agency recently sent St. Petersburg a consent order to ensure the city corrects its sewage capacity problem and minimizes future spills.
But city officials have said a fix will take at least two years.
Until then, it's swim at your own risk around downtown St. Petersburg after major storms.