ROCKWOOD – Residents might want to keep their mouths closed while swimming at the Rockwood Conservation Area beach this summer... or at least until its E. coli levels have lessened.
According to the beach conditions section of the Grand River Conservation Authority (GRCA) website, five water samples tested at the Rockwood Conservation beach had an average of 1,038 E. coli per 100 ml of water on June 20.
Likely "highly related" to surrounding sources of contamination and animals in the area, manager of communications at Wellington-Dufferin-Guelph Public Health Chuck Ferguson said anything over 1,000 per 100 mL means multiple samples collected at the location had high levels of E. coli.
Ontario's Ministry of Health recommends water samples have a maximum average of 200 E. coli per 100 mL of water to reduce the risk of water-borne illness related to recreational water use at public beaches and waterfronts.
"E. coli tested is just an indicator bacterium to assess potential health risk if exposed to the water. The presence is an indication of fecal contamination, likely birds, and other animals," said Ferguson. "While some indicator bacteria pose a risk to human health, not all do. The presence just suggests that there are potential pathogens."
One of nine conservation area beaches in eight Grand River Conservation Areas throughout the watershed, Rockwood is the only location with levels exceeding an average of 100 E. coli per 100 mL of water.
When asked what would cause such high levels of E. Coli, manager of communications for the GRCA Lisa Stocco said natural water bodies like Rockwood Beach are exposed to contamination from various sources and water quality conditions can change very quickly due to environmental factors like recent heavy rainfall or a large number of birds or wildlife.
"The level that was noted (on June 20)...would have been related to local environmental conditions at the time the sample was taken," said Stocco in an emailed statement.
Used to determine long-term trends in water quality at the GRCA swimming areas over time, Stocco said the water quality monitoring data is "not useful" in identifying public health risks when swimming in natural water bodies because "it does not provide timely information to the public."
Instead, residents should rely on the additional information posted on the GRCA website and posted signage to help "make timely decisions when choosing to swim (or not) in a GRCA water body," said Stocco.
When asked what amount of E. Coli would warrant a beach closure, Stocco said the GRCA wouldn't typically issue an E. coli-based closure unless they saw a recurring problem over a large period from multiple samplings.
As beach closures are "rarely issued," Stocco said it's important to keep in mind that there is "always a level of risk" when swimming in a natural water body and the GRCA has added signage to each location and updated its website to communicate beach conditions and help the public make informed decisions.
"We don’t use the water quality sampling data posted on our website to make public health decisions, as it is not timely," said Stocco. "That said, if we were to consistently see high E. coli counts at a GRCA natural swimming area, we would be investigating that further and determining whether a closure or additional communication to the public was needed."
The GRCA conducts water quality sampling for E. coli counts every other week during the warmer months, typically beginning in June, and through July and August.
Stocco said new samples were collected on July 4 but there was an issue at the external lab the GRCA uses to analyze the samples and the results have not arrived yet.
Isabel Buckmaster is the Local Journalism Initiative reporter for GuelphToday. LJI is a federally-funded program.
