Canadian Registered Charity (855745220RR001).


Challenges of the Great Lakes

Even though it’s easy to feel dwarfed by the immense size of the Great Lakes, it’s also important to realize that despite their impressive size, the lakes are really a very fragile ecosystem. Human activity has been playing a serious role in the decline of the quality of aquatic and nearshore ecosystems, so it is important to educate yourself on what is happening to the lakes in order to know how you can help.

The 3 main causes of concern for the Great Lakes are:

  • Pollution
  • Development pressures
  • Invasive species


Tire in waterHuman impact has a dramatic effect on the health of the lakes and the ecosystems that surround them. The lakes only replenish 1% of their water supply each year. This means that the things we put into them tend to stay there for a long time. So, it’s important to think about how we use the water that comes out of the lakes and what we put into them.

Pollutants can be of great concern to lake ecology. Substances like mercury, dioxins and polychlorinated biphenyls (PCBs) that result from industrial processes have been released into the lakes for decades. Some of these chemicals and pollutants have resulted in decreased biodiversity in the Great Lakes Basin, even though much has been done since the 1970s to curb the flow of waste into the lakes.

In recent years, concerns over nutrient levels have been of the greatest concern. High levels of phosphorus and nitrogen can cause increases in algae blooms, which leave the lakes low on oxygen, making it difficult for native fish and wildlife to survive. Many detergents, soaps and cleaning products are high in phosphorus and nitrogen – always try to buy low-phosphorus detergents. Fertilizers that you put on your lawn contain these elements as well. Be sure not to over-fertilize your lawn, since much of that excess fertilizer can end up in the Lake as the rain washes it off and down storm drains. For more information on phosphorus levels in the Great Lakes, click here.

dead fishAlong with all of the chemicals that we have known about for years, there is also emerging concern over ones you would never have thought of as harmful. Flame retardants, which are common in many consumer goods, have been shown to act as endocrine disruptors, inhibiting the proper formation of the neurological and reproductive systems of some species. Even pharmaceuticals – pain medication, cholesterol-reduction medication, birth control – are proving to be detrimental to the natural habitat in the Great Lakes Basin. These medications pass through us and are not removed by wastewater treatment systems.

Given that everything we put into the lakes will be there for a long time, it is very important to always think about what products you’re using – in your home, in your yard, at your workplace – and what you are putting into the lakes. Tips on What You Can Do to protect the Great Lakes against pollution can be found on the next page.

Development Pressures

burlington shoreline developmentThe Great Lakes Basin is home to over 30 million people in North America. Nine million Canadians call it home, and that number is expected to climb rapidly in the coming years. Halton Region alone is projected to grow to 1,000,000 people by 2041, up from the current population of about 520,000 (2015). A similarly large growth target is set for the overall GTHA (see Ontario's Places to Grow Act for more information). Burlington will need to absorb its share of this growth.

More people living around the Great Lakes means potentially more water pollution if we're not careful about reducing our impact through better living habits and workplace practices. It is also likely to lead to more pressure on the natural ecosystems that surround the lakes and their tributaries. We risk losing or degrading more natural landscapes such as wetlands, forests, grasslands and sand dune habitats, which are all vital for the health of the lakes. It is increasingly important for all Ontarians to protect and preserve the natural landscapes that we do have left in the Great Lakes Basin.

Invasive Species

garlic mustardThe Great Lakes are one of the most diverse ecological systems in North America and are home to over 4,000 species of plants and animals, yet that diversity is not easy to maintain – there are always invaders 'knocking on the door'. They are species that come from other parts of the world that have no natural predators or controls here in the Great Lakes Basin – species that threaten its rich biodiversity.

They have arrived here over the years clinging to boats, from foreign ships dumping their ballast water, through movement of wood from one region to another, and from people importing and planting trees and plants for aesthetic appeal in yards and gardens.

Invasive species have been identified as the second most significant threat to biodiversity, second only to habitat loss. When these species establish themselves in a place where natural controls do not exist (eg. other species, certain climatic and growing conditions), the results can be catastrophic for native species of plants and animals. One of the most important things you can do for your Great Lakes is learn how to identify invasive species and report them any time you see them. Through early reporting, you could potentially stop them from spreading and causing significant damage to natural ecosystems!
Invasive removal

Here's some more information on invasive species of concern to our Great Lakes:


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