Today I asked the staff at PSCinflatables.ca ("SWIMMING ZONE" and "WATERPARK") what is the e coli count and they said it was 5 CFUs per 100ml which is 1/20th of the maximum level of 100 considered safe for swimming.
It appears that RBC Echo Beach (Brigantine Cove) has the lowest e coli count of any beach in Toronto, making it perhaps Toronto's safest place to swim.
I think I'll swim and watch the sun go down at Echo Beach, https://www.youtube.com/watch?v=QEQkIEkxm7k