The Seine concerns Olympians. How do I know if my favorite Kentucky swimming hole is safe?

LEXINGTON, Ky. (July 31, 2024) — Concerns over the water quality of Paris’ River Seine have plagued the run-up to the Summer Olympics.  

Athletes and local residents have questioned the safety of the river — which is set to host open-water swimming competitions like triathlon and marathon swimming. Event hosts and public officials have tried to make sure the urban waterway has bacteria levels safe enough for competition while trying to assuage public concerns. In mid-July, Paris’ mayor took a public dip in the river to proclaim its safety.  

But what about here in Kentucky? The Commonwealth has more than 90,000 miles of streams and rivers. How do we know if our favorite natural swimming hole is safe for a swim? 

UKNow posed the question to University of Kentucky experts. Anna Hoover, Ph.D., an associate professor in the UK College of Public Health spoke about the perceived public risks associated with swimming in the Seine and Kentucky’s waters. Jason Unrine, Ph.D., director of the Kentucky Water Research Institute, addressed water quality guidelines for recreational swimming in Kentucky. 

UKNow: What is risk perception?  

Hoover: Risk perception is not just about the potential likelihood or severity of something unfortunate happening but also about how we as humans understand that potential threat. We tend to run facts and data through our own personal filters. These filters have been formed in part by our past experiences, stories we have heard, what level of control we feel over the threat, who we trust and other factors that add up to influence our expectation of what is going to happen. Often, the risk from the hazard itself can be very different from how people perceive their risk from the hazard. In such cases, it is important to use data to help people understand the actual risk while also respecting that their levels of concern are based on a much more complex set of influences. 

UKNow: How have you seen risk perception play a role in the discourse around the Seine/Olympics?  

Hoover: As with many urban rivers, the Seine’s history of pollution during and since the industrial revolution has clearly influenced folks’ perceptions of the risks related to swimming in it. In fact, swimming in the Seine has been banned for more than 100 years now because of pollution. And, of course, people are aware of the historical impact of deadly waterborne diseases, so yes, the retrospective or backward-looking nature of risk perception certainly has helped drive high levels of concern around Olympic swimming events being held in the Seine.  

These perceptions have been reinforced by recent tests, which have indicated repeatedly that the presence of E. coli is above acceptable levels, particularly when it rains. Depending on weather conditions over the last few weeks, E. coli levels have been as much as 10 times higher than what is considered acceptable. Of course, those numbers do drop when the weather improves. Nevertheless, the knowledge that E. coli levels have been so high recently is likely to continue driving risk perceptions regardless of what actual monitoring data indicate on any given day. And feeling that they have little to no control over whether their events will be held in the Seine, athletes’ outrage about the events being held there may continue increasing, even if tests indicate that water quality is acceptable on the day of an event.   

UKNow: Here in Kentucky, what benchmarks does a natural body of water have to meet to be considered safe for swimming?  

Unrine: Kentucky has criteria for recreational waters divided into two categories, primary contact recreation, which includes activities where you can be submerged completely in the water, and secondary contact recreation where you wouldn’t necessarily be submerged, like boating or wading. 

For primary contact recreation, from May 1 through Oct. 31, the 30-day geometric mean of E. coli can’t exceed 130 colony forming units per 100 milliliters of water and the pH should be between 6 and 9.  For secondary contact, the 30-day geometric mean fecal coliform bacteria shouldn’t exceed 1000 colony forming units per 100 milliliters of water and the pH should be between 6 and 9.   

There are other important details about these criteria which are outlined in the Kentucky Administrative Regulations, specifically 401 KAR 10:031, section 7.  

UKNow: How can poor water quality affect a swimmer?  

Unrine: Parasites like Cryptosporidium and Giardia, bacteria such as E. coli, and viruses are common in contaminated water and can cause infections. Some of the symptoms of bacterial, viral and parasitic infections include upset stomach, rashes, eye or ear infections, diarrhea, respiratory infections and vomiting. There is also concern about exposure to toxins from harmful algal blooms. These algal toxins can cause diarrhea, nausea, vomiting; skin, eye or throat irritation; allergic reactions or breathing difficulties. 

UKNow: Does it play a role in the way we assess risks related to swimming in public bodies of water here in Kentucky? 

Hoover: A large percentage of the Kentucky waterways that have been assessed do not support contact recreational activities like swimming. However, it is possible that not everyone is aware of local water quality issues and that people may continue using impaired waterways for recreation. My hope is that the dialogue around the Seine during the Olympics will increase Kentuckians’ curiosity about their own waterways and lead us all to consider not only the potential risks we may face from pollution but also ways we as individuals and communities can help prevent future pollution and clean up what is already there. 

UKNow: What are some best practices for caring for our local waterways?