Ottawa Public Health tested city beaches once a week this summer instead of daily, and a growing disagreement over that change has put the spotlight on how much residents actually know about the water they swim in.
OPH reduced its beach water testing from daily to weekly last year, after concluding many residents were mistakenly treating lab results as real-time indicators of water quality. Ottawa Riverkeeper argues the shift has left swimmers with less timely information about beaches where conditions can change rapidly.
"You have a huge part of the population that doesn't think the water is safe enough and perceives the river as contaminated," Laura Reinsborough of Ottawa Riverkeeper said in an interview with iPolitics.
OPH tests beach water for E. coli, bacteria that signals contamination from fecal matter, whether from wildlife, pets, stormwater runoff or sewage. Under Ontario guidelines, a swimming advisory is triggered when a geometric mean of five samples exceeds 200 E. coli per 100 millilitres.
The health unit defended the revised program in a statement to iPolitics, saying it is meant to monitor "longer-term" water quality trends rather than provide "real-time information on beach water quality." Because lab testing takes 18 to 24 hours, OPH said results already reflect the previous day's conditions, and residents can instead make swimming decisions based on real-time factors.
The agency says the approach aligns with Ontario Public Health Standards and Health Canada's recommendation of at least weekly monitoring. In a September report to the Board of Health, OPH found daily sampling correctly reflected beach conditions about 80 per cent of the time, compared with roughly 79 per cent for weekly sampling — concluding the extra testing offered little improvement because environmental conditions can shift quickly.
Reinsborough, whose team also runs supplementary testing at supervised city beaches, said results can fluctuate dramatically day to day. A single weekly sample can paint a misleading picture if it's taken just after rainfall, she argued.
"It could be deterring people on a day when it's actually quite safe to go in, and to tell you that it's safe on a day when actually it's not," Reinsborough said, pointing to this year's Canada Day storm. "That's the issue we're coming up against."
After heavy rain, OPH advises residents to wait 48 hours before swimming. But Reinsborough said testing at Petrie Island Beach after the Canada Day storm found E. coli at three times the allowable limit two days later.
"After 48 hours, the beaches were almost 700 coliform units… for those people who are in the water, they are at risk," she said.
Swallowing contaminated water doesn't guarantee illness, but it can raise the risk of gastrointestinal infection. Dr. Lawrence Hookey, Division Chair of Gastroenterology at Kingston Health Science Centres and Queen's University, said most people who get sick experience diarrhea that resolves on its own within days, though some strains cause more serious illness. Young children and people with weakened immune systems face greater risk.
Banu Ormeci, a Carleton University professor and Jarislowsky Chair in Water and Health, said both sides have a point: lab results are always a day old. But she argued less testing shifts the burden onto residents to interpret complex data.
Ormeci's team tested the Rideau River and Mooney's Bay last year and found the river suitable for recreational use. Beaches with consistently high E. coli, like Mooney's Bay with its relatively stagnant artificial water, are often shaped by local conditions such as shallow water, poor circulation and stormwater runoff, she said.
Orléans East-Cumberland Coun. Matt Luloff, whose ward includes Petrie Island, said he understands OPH's reasoning. Rather than debate old lab results, he'd prefer Ottawa pilot technology such as ColiMinder, which he said could provide "automated microbiological water quality readings, rather than waiting 18 to 24 hours for traditional laboratory results."
