Lake Ontario Water Quality: Can I swim in it?

TLDR: Yes, I swim year-round in Lake Ontario.

However, as SwimDrinkFish put it... "Choosing to enter the water shouldn’t feel like a game of Russian roulette." Lake Ontario Waterkeeper suggests there is 3-8% chance of getting sick whenever you swim in these waters.

This is beyond sad to me, especially since Lake Ontario has 25% of Canada's population living around it (Great Lakes Guide) and is the source of drinking water for 9 million people in Ontario, Canada and New York State, USA (Lake Ontario Waterkeeper)

Current estimates show that Lake Ontario and Lake Erie are the most polluted of the Great Lakes.

Although Lake Erie is smaller and more shallow, this shows how Lake Ontario is really struggling. All other lakes flow into Lake Ontario, giving it their pollution and it has the closest proximity to massive farm and business run-off (Live Science).

Lake Ontario Demise

A brief look into colonial history will show us where the problem began.

In the 1800's, overfishing and pollution began harming the ecosystem. Followed by rapid development and human activities in the 1900's (Lake Ontario Waterkeeper)

In 1988, a government scientist named Murphy found oozing, black goo from a coal tar distillation nearby Hamilton, Ontario. The violent compounds were found while he was sampling at Randle Reef, an area of concern and one of the largest, most contaminated sites on the Great Lakes.

Instead of removing the black blob entirely, it was decided to put a $39 million dollar box around it made from steel - from the company Stelco (who apparently contributed to this mess to begin with) (The Narwhal).

Fish travel back and forth from the ocean to this freshwater lake. Before the dams, the eel and sturgeon used to migrate in enormous numbers. But now, our settler-colonial ways of doing have led to 10 species extinctions and 15 invasive introductions (Lake Ontario Waterkeeper).

Now, the greatest threats to Lake Ontario are urban development and habitat destruction, pollution and electricity generation, invasive species and climate change; as well as sewage and stormwater pollution. Most of these issues have stemmed from the surrounding industrial centers and agriculture (Lake Ontario Waterkeeper & Great Lakes Guide).

Swimming in Sewage

In 2019, Ontario Place - the only public, swimming beach in downtown Toronto, had a water testing pass rate range of 50-90%. It still has significant sewage and floatables present.

In fact, there was even an incident of 50+ condoms that floated to the surface of this highly used beach. Sewage outfall and leaking is problematic because it carries bacteria that affects the risk of contracting a waterborne illness during wet and dry weather events. For instance: 19,863 e.coli/100ml is considered high and when this amount was tested for by SwimDrinkFish, the city was alerted and an investigation took place (SwimDrinkFish).

Although Toronto currently has 8 blue flag beaches: more monitoring and transparency are needed to alert the public of these overflow events. (SwimDrinkFish)

Down the Drain

Each day, Toronto homes and businesses flush polluted water down the drain. This wastewater has more than just bacteria from human waste, it also contains pharmaceuticals, harsh cleaning products and other household hazardous waste. Many of Toronto’s businesses dump chemicals into the sewer system like industrial strength cleaning products, degreasers, heavy metals and more.

Toronto Water can remove some contaminants when they treat the wastewater at their four treatment plants, but many toxic chemicals are released into Lake Ontario (TEA).

In 2011, these plants released over 7 tonnes of Cadmium, Mercury, Lead and Nickel into the lake (TEA). In addition, the lake also contains: PCBs, aldrin/dieldrin, DDT/DDE, Toxaphene, Dioxin, Chlordane, Hexachlorobenzene & Octachlorostyrene (Ontario.ca).

Mercury is one of the top toxic chemicals released into Toronto air and water. The Scarborough Highland Creek sewage incinerators are the city’s largest mercury polluters. The Toronto Environmental Alliance (TEA) monitors existing policies like the Sewers By-Law to ensure water polluters are held accountable. and also joined the Health Impact Assessment Stakeholder Group — hoping for a no-burn solution that reduces health risks in the community. They want a policy that would stop mercury at the source before it enters the sewer system (TEA - Mercury).

In 2014-2015, they focused on strengthening the Pollution Prevention Plan of Toronto’s Sewers By-Law and added new substances of concern to the list, as dozens of other chemicals pose risks to the Great Lakes and were not on the list (TEA).

Algae, Invasives & Climate Change

As most summer swimmers know, there is algae in the lake.

Algae of concern is; green (cladophora spirogyra) and blue-green (microcystis) algae.

Blue-green algae is the most troublesome as it can contain toxins or other noxious chemicals to people and aquatic species. Microcystis is a poor source of food for zooplankton, it contains toxins that are dangerous if ingested by people or animals and can cause liver damage. Climate change has unfortunately increased water temperature and also prevents water in lakes from mixing, so these algal mats grow thick and fast (Ontario Biodiversity Council).

Masses of decaying algae from algae blooms live at the bottom of the lake and deplete the oxygen supply, these are called "dead zones" as fish cannot survive here. Algae comes from excess nutrients, such as phosphorous and nitrogen from agriculture and urban development, and thrives in warm temperatures with a lot of light (Ontario Biodiversity Council).

In the 1960’s, Lake Erie was covered in a green slime from phosphorous but by 1972, a massive clean-up ensued and made a huge, positive impact to the lake. So, it can be done. But for the past decade, the massive and harmful blue-green algae has reappeared, as increased inputs of phosphorus from agriculture and urban areas, pesticides and other chemicals have increased (Ontario Biodiversity Council).

In addition, Quagga Mussels and Zebra mussels, invasive species that are replacing the native, freshwater mussels - only selectively remove edible algae, but not enough to make an impact (Ontario Biodiversity Council).

Water Monitoring with SwimDrinkFish

SwimGuide was started in 2001 by an environmental lawyer after the water tragedy in Walkerton that killed people and made thousands sick. It is a nonprofit organization that uses community science and communications technology to help people connect and safeguard local waters. It operates in 11 countries and has 4 million users. In addition, it has helped secure 1.5 billion in commitments for contaminated site cleanups in southern Ontario and saved more than 1.6 million fish (SwimDrinkFish).

SwimDrinkFish has an excellent swim guide website and app that shows the water quality of nearby beaches through a search tool. Through this app, I was able to learn that Woodbine Beach in Toronto was sampled on August 12th and passed 99% of the time. Whereas, Humber Bay West in Toronto: received a less than 60% pass rate, due to its close proximity to Humber Treatment Plant and had a 44% fail rate (SwimDrinkFish).

Engage at City Hall

Toronto Environmental Alliance (TEA) is another organization that makes sure we have Blue Flag swimmable beaches & also engages at City Hall to prevent pollution from entering Lake Ontario. They have also created a helpful map to show the Toxics in Toronto (last updated in 2005).

So, can you swim?

Yes, you can swim here. But with each swim comes with a risk of getting sick. Knowing the myriad of problems this beautiful lake faces, should compel all of us to be better waterkeepers.