Here’s What a Microbiologist Wants You to Know About RFK Jr.’s Creek Swim

When the temps heat up, there’s nothing better than a refreshing swim to cool off—but if the water you’re wading in isn’t exactly up to snuff, the experience can turn way less chill. And earlier this week, the top public health official in the US reminded us all of that.

Over the weekend, Robert F. Kennedy, Jr., the head of the US Department of Health and Human Services, went viral for taking a dip in Rock Creek, a notoriously sewage-saturated channel that runs through Washington, DC’s Dumbarton Oaks Park. In a Mother’s Day post on the social media platform X (formerly known as Twitter), Kennedy shared photos of himself hanging out in the water (in what appeared to be jeans, no less), accompanied by two of his grandchildren as well as other family members. The pics sparked a lot of…thoughts, so we decided to do a deep dive (sorry) into why this activity could be a legit health risk—in case the words “sewage-saturated” didn’t already clue you in.

Some important background: Thanks to issues like trash accumulation, polluted runoff, and, yes, “sewage overflows,” Rock Creek is known for “high levels of bacteria and other infectious pathogens that make swimming, wading, and other contact with the water a hazard to human (and pet) health,” according to the National Park Service. One example is E. coli bacteria, which also serves as a telltale sign of contamination with fecal matter (a.k.a. poop), Bill Sullivan, PhD, a microbiologist and professor at the Indiana University School of Medicine, tells SELF. “If there is animal feces or agricultural waste in proximity to the waterway, storms or rain can push that contaminated soil into the water,” he says. Besides E. coli, other potentially present pathogens include Salmonella; viruses like rotavirus, norovirus, and hepatitis A; and parasites like Cryptosporidium, Giardia, and Toxoplasma gondii, according to Dr. Sullivan. What’s more, the water doesn’t have to look visibly dirty (or feel different on your skin) to contain any of the above, so you can’t know if you’re in the clear just by eyeballing it.

Coming into contact with these bugs isn’t only nasty, it can also be dangerous, since they can make you seriously sick. Think of entering Rock Creek (or a similarly dirty body of water, like Paris’s River Seine, a venue for the 2024 Olympic open swimming events despite widespread controversy over its safety) as “aquatic Russian roulette,” Dr. Sullivan says. “When you’re dealing with these fecal-contaminated waters, you might get lucky on one day, but you might not get lucky the next day, so it’s just not worth the risk.” If you do develop an infection, you can expect symptoms of stomach distress like cramps, nausea, vomiting, and diarrhea, according to Dr. Sullivan.

Besides those GI issues, Dr. Sullivan adds, you could potentially also be at risk for more serious side effects, like severe dehydration (if the diarrhea or vomiting is bad enough), liver failure (in the case of hepatitis A), or miscarriage or birth defects during pregnancy (in the case of Toxoplasma gondii). What’s more, older people—like Kennedy, who is 71—and young children tend to be especially vulnerable to more intense illness and complications.