Being located near large bodies of water comes with many advantages and disadvantages.
The lifestyle and breadth of industries is undeniably different from places that are not located near an ocean, a sea, or a lake. There is a big difference between living near either of these bodies of water, but this short (and also technically a test) PSA will address a very specific issue around Lake Ontario.
Toronto, which is situated on top of the west end of Lake Ontario, has experienced minor water quality issues for a very long time. The Toronto public beaches, which are among the most popular destinations in the summer, experience many issues with water quality. The City of Toronto monitors the water daily in the summer months and decides on whether it is safe to swim in water conditions at the time. It seems to fluctuate constantly, with several long periods of high E. coli levels that make it unsafe to swim in Toronto waters.
E. coli is naturally found in the intestines of a humans. Although E. coli is not the most dangerous bacterium to be exposed to, there are many specific strains that can affect your health when at high levels. Virulent strains have been connected to outbreaks of gastroenteritis, urinary tract infections, Crohn's disease, and many more. Symptoms include abdominal cramping, diarrhea, vomiting, and fever, just to name a few. Very young children are especially susceptible to diseases coming from E. coli, but it is still something you want to avoid regardless.
Garbage pollution and eutrophication (this is when the water turns green and is overrun by algae) are also risks you want to avoid that affect Toronto water systems every year. There is no need to explain garbage pollution, but eutrophication can seriously degrade water quality very quickly through algal blooms that suck nutrients, sunlight, and oxygen away from the water. This kills surrounding wildlife, including organisms that can keep bacteria like E. coli in check. It is also not advisable to swim in, for many health related reasons. When there is very little water flow and long residence time (average time that water spends in a lake or pond), eutrophication occurs and water quality will always be questionable. If you would like to learn more about eutrophication, there are many online resources that can explain it in great depth.
Toronto beaches are a part of the Blue Flag Program, which is an internationally recognized program that awards "blue flags" to communities that keep high-standard of water quality. Generally, Toronto waters are good to swim in most of the time. Always watch out for Toronto Public Health alerts in the summer, and safe swimming!