Ottawa’s short summers are best enjoyed at the beach, but as the season goes on, soaring temperatures can cause the E.Coli level of swimming areas to rise, too.
Ottawa Public Health posts daily results for Britannia, Mooney’s Bay, Petrie East Bay, and Petrie River Beaches. The results take roughly 18 hours to update, so all recommendations from OPH are based on yesterday’s test results.
OPH will recommend avoiding swimming at a beach if ‘the geometric mean of 5 water samples taken on the previous day is greater than 200 E. coli per 100mL of water (Ontario water quality standard for beach water quality)’. They may also do so if there has been a weather or on-site event that may affect water quality.
As of July 20th, here’s which of Ottawa’s beaches are best for swimming, according to water test results.

Via Ottawa Public Health
From the list, you can see that Petrie River beach is the closest to reaching a level that does not meet provincial bacterial standards, while all three other beaches tested are well within this range.