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Lake Superior

Lake Superior

Lake Superior may be considered to be the "Greatest" of the Great Lakes and it contains more water than all the other Great Lakes combined. It is also the deepest Great Lake and has the coldest water temperature which is on the average, only 4°C. Some of the world's oldest rocks, about 2.7 billion years old, can be found on the Ontario Shores of the lake.

Almost one million people in both Canada and the United States live in the Lake Superior watershed yet is it considered to be sparsely populated. This helped keep over 90% of land in the watershed covered by forest. The extensive forest cover supports the main industries in the watershed: forestry, mining and recreation. The natural forest cover in the watershed maintains the high water quality found in Lake Superior and it is considered the cleanest Great Lake. Like all the Great Lakes, Lake Superior is threatened by climate change and invasive species.

Lake Michigan

Lake Michigan

Contained entirely within the borders of the United States, Lake Michigan is the only Great Lake not shared by Canada and the United States. Over 12 million Americans live in the Lake Michigan watershed, making it the most populated of any Great Lake watershed. Most people live in the southern portion of the lake, where industry and agriculture are the primary industries. Natural resource sectors and tourism dominate the economy in the Northern half of the lake, which is sparsely populated. Tourism draws in millions of people annually, who come to visit the beaches of Lake Michigan, which include the world's largest freshwater dune system.

Lake Huron

Lake Huron

Lake Huron is the second largest Great Lake. The Lake contains more than 30,000 islands. Including the shoreline of its islands, Lake Huron has the largest shoreline length of all the Great Lakes.

It is the only Great Lake that lacks a major city centre on its shores, and approximately 2.5 million Canadians and Americans call the watershed home. Residents in the watershed are dependent on natural resource sectors and tourism to support a strong economy. The world's largest freshwater island, Manitoulin Island, and longest freshwater beach, Wasaga, attract thousands of tourists and cottagers each summer. Lake Huron is threatened by climate change, changing water levels and invasive species.

Lake Erie

Lake Erie

Lake Erie is the smallest, shallowest and most southern Great Lake. These factors contribute to making it the warmest of the lakes, where summer water temperatures can reach as high as 27°C. The ecosystem of Lake Erie is extremely complex and includes a greater diversity of plants and animals than the other Great Lakes. With a fish population of 46 million, the warm waters of Lake Erie support more fish than any other Great Lake and sustain the world's most productive walleye fishery. The climate and fertile soil surrounding Lake Erie support a strong agricultural industry but manufacturing and shipping are also important for the local economy. Due to intensive agriculture and human development, the watershed has the least amount of natural plant cover of all the Great Lakes. Urban and industrial pollution, eutrophication, climate change, and invasive species all threaten the biodiversity and complexity of the Lake Erie ecosystem. Only about 21% of the land that drains into Lake Erie is covered by forest, making it the least forested watershed of the Great Lakes.

Lake Ontario

Lake Ontario

The Lake Ontario watershed is home to over 7.5 million Ontarians, more than any other Great Lake. While Lake Ontario has a slightly smaller surface area than Lake Erie, it is much deeper and therefore contains more water at cooler temperatures than Lake Erie. Agriculture, manufacturing, and shipping are the base for the economy and major economic centres such as Toronto and Hamilton are found on the shores of Lake Ontario. As the last Great Lake before the St. Lawrence River, all the Great Lakes drain through Lake Ontario and it is negatively impacted by the pollution originating in the other lakes. Additionally, the large population base and associated development along Lake Ontario shores threaten to decrease water quality, nearshore habitats and biodiversity in the lake.

Water enters Lake Ontario from Lake Erie through the Niagara River. Lake Ontario is about 100 meters lower in elevation than Lake Erie, and this difference helps to produce Niagara Falls.

80% of the water in Lake Ontario comes from the other Great Lakes, while about 14% comes from other rivers and streams that flow in the Lake. The remaining water is contributed to Lake Ontario from rain and snowfall.

St. Lawrence River

The St. Lawrence River

The St. Lawrence is Canada's third longest river. The St. Lawrence system has been changed significantly from its natural state. It has been dredged and diverted in order to form the St. Lawrence Seaway, one of the world's busiest shipping corridors and commercial waterways and it has been dammed to produce hydroelectricity. The St. Lawrence River links the Atlantic Ocean with the Great Lakes and supports a population of about 30 million Americans and 15 million Canadians. It includes lakes and channels, a long estuary, and a gulf. The area is home to richly diverse habitats and many species of fish, birds, and wildlife. Stressors on the St. Lawrence are similar to those of the Great Lakes threatening water quality, biodiversity and wetlands.

Stressors on the Great Lakes & the St. Lawrence River

The Great Lakes and St. Lawrence River are in trouble. A combination of the impacts from rapid population growth, changing land uses, and climate change are affecting water quality, water levels, wetlands and other natural habitats, and the fish, insects, birds and other wildlife that depend on those habitats.

What happens in the watersheds upstream impacts conditions downstream in the Great Lakes and St. Lawrence River.

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Climate Change

Climate ChangeThe Great Lakes and St. Lawrence River are already being impacted by a changing global climate. Increases in air and water temperatures cause less ice cover, increase evaporation rates and impact water quality and fish populations. It is also expected that water levels in the Great Lakes will decrease. Water level changes can have impacts on many habitats, but especially in important wetlands that require specific water levels to provide many important functions such as storing and filtering water.

It is also expected that there will be larger and more frequent storm events leading to increased water runoff and degraded water quality. Communities and watershed practitioners such as Conservation Authorities have already begun to develop climate change adaptation strategies designed to reduce impacts and protect important natural systems and features.

Changing Water Levels

Changing Water Levels Changing water levels in the Great Lakes are having social, economic and environmental impacts. They impact access to water for lakefront property owners, recreational boating and commercial shipping on the lakes, and reduced habitat for aquatic species. In addition, artificial controls of the waters in Lake Ontario and the upper St. Lawrence River are a stress on wetlands, which rely on periodic high and low waters.

Algal Blooms

Algal Blooms More algae is growing in Great Lakes waters. This increase is caused by an excess of nutrients in the water, mainly as a result of upstream runoff, and is being exacerbated by climate change. Some shorelines are covered by slimy masses of nuisance algae, which degrades the quality of waterfronts. In the fall of 2011 there were record levels of potentially toxic blue-green algae in Lake Erie. Some bays in other parts of the Great Lakes, such as the Bay of Quinte, also experience problems with these blue-green algae blooms. Individuals swimming or boating in these harmful blue-green algal blooms can be exposed to toxins. There are also public concerns about their impacts on drinking water.

Untreated Industrial Waste

Untreated Industrial Waste To protect our Great Lakes and St. Lawrence River, industrial wastes must be properly treated before they are discharged into streams, rivers and lakes. Petrochemical, pharmaceutical, mining, food and beverage, and paper and textile industries are some of the industries that are required in Ontario to make sure they have adequate protections in place. Additionally, air emissions from factories such as sulfur and nitrogen can enter the water cycle, fall to the ground or onto surface waters as acid rain and pollute the groundwater and the Great Lakes.

Loss of Wetlands

Loss of Wetlands

Wetlands are important because they help to control flooding and erosion, store excess water and slowly release it during periods of drought, and also help to improve water quality by filtering sediments and contamination. Ontario has lost more than 90% of its original wetlands to development. This has created hardened shorelines (no natural cover) and reduced the amount of habitat for wildlife, fish, birds, and insects.

Chemicals of Concern

Chemicals of Concern There are increasing concerns about the impact that some newer chemicals may have on the Great Lakes and St. Lawrence River ecosystem and human health. These chemicals can originate from urban, industrial or agricultural sources. Some of these chemicals come from everyday products such as shampoo, sunscreen, pharmaceuticals and plastics. Sewage treatment plants were not designed to remove some of these chemicals, enabling these chemicals to end up in the Great Lakes and St. Lawrence River. Currently, the impact that many of these chemicals can have on our environment and health is uncertain or unknown. In order to protect our Great Lakes, the St. Lawrence River and other water sources from potentially harmful effects, keeping these chemicals out of our sewers is the best approach.

Loss of Fish & Wildlife Habitat

Loss of Fish & Wildlife Habitat
Photo: Lou Wise

Loss of fish and wildlife habitats in the Great Lakes – St. Lawrence region affects ecosystem health. Reducing fish and wildlife habitats reduces commercial and sport fishing, recreational, and tourism opportunities. Additionally loss of fish and wildlife habitat contributes to the loss of natural and cultural heritage in Ontario. The Great Lakes is home to 3,500 plant and animal species, including 46 species that are not found anywhere else in the world. The numbers of some Great Lakes plant and animal species, such as the Blanchard's Cricket Frog, have declined to the point where they are at risk in Ontario and are now protected under the Endangered Species Act, 2007.

As natural habitat is lost or decreases, more species in the Great Lakes region may become endangered or threatened. By protecting natural spaces in the Great Lakes region, we can protect animals and plants.

Invasive Species

Invasive Species Invasive species, also known as alien, exotic, or non-indigenous species, are species found outside their natural habitat or range. Invasive species are the leading threat to biodiversity in the Great Lakes, and may interact with and exacerbate other stressors, such as climate change.

The Great Lakes – St. Lawrence ecosystem has over 180 reported non-indigenous aquatic species, more than any other ecosystem on earth. While some species have been introduced to the Great Lakes on purpose for economic or cultural purposes, other species have been introduced accidentally. Non-indigenous species have been introduced to the Great Lakes through shipping, the aquarium and horticultural trades, fisherman's bait buckets, live fish markets, and to support the fishing and agricultural industries. Non-native fish species, such as rainbow trout, are stocked to support the sports fishing industry.

Invasive zebra and quagga mussels can blanket lake bottoms and create a phenomenon called the "nearshore shunt". The nearshore shunt is caused when the invasive mussels store nutrients such as phosphorus, preventing these nutrients from reaching the deeper, offshore waters of the Lakes. This decreases food available for fish and increases the amount of algae found on beaches and shorelines.

It has been estimated that 42% of native species in the Great Lakes are currently threatened by invasive species. Controlling and mitigating the impacts of invasive species is estimated to cost Canadians over $187 million per year.

Population Growth

Population Growth Within Ontario, future population growth will likely continue to be concentrated along areas closer to the Great Lakes and St. Lawrence River. Population growth can have economic benefits, however, it can also cause stress on natural areas and systems. People require spaces to live and work, and building new infrastructure can cause a further loss of forests, grasslands, wetlands and agricultural lands. More people can also increase both air and water pollution. More cars are on the road, more water resources are needed, and more electricity is generated. Additional roads and other paved surfaces create direct pathways for contaminants to flow to streams, rivers, and eventually the Great Lakes or St. Lawrence River.

Out of Sight, Out of Mind

Out of Sight, Out of Mind With our busy lives today, we forget that we live so close to such an important natural resource and that our actions can impact conditions in the Great Lakes and St. Lawrence River system. Using water unnecessarily, applying excessive amounts of fertilizers or pesticides that can wash into rivers and streams and then into the Great Lakes, or changing our shorelines by removing natural plants and trees - all of these types of actions can add up. The water and ecosystems of the Great Lakes and St. Lawrence River cannot just 'naturally' recover and regenerate from all our cumulative and ongoing impacts. There are limits to how much they can adapt. Consequently, we run the risk of not being able to rely on them to provide clean water for our children.

Runoff

Runoff
Photo: Lou Wise

When water falls to the ground in watersheds as rain or snow, it begins to move and picks up pollution such as road salt, fertilizer, and pesticides; gas, oil and trace metals; bacteria from wildlife and pet waste. Runoff drains into local bodies of water and is carried to the Great Lakes and St. Lawrence River - which act as a drinking water source for about 80% of Ontarians. Runoff causes decreased water quality and reduced diversity of plants, animals and fish that rely on good water quality. It can also impair important natural wetlands that help to protect shorelines and watersheds.

Bacteria

Bacteria
Photo: Visions of America / Shutterstock.com

Most of the time, the majority of Ontario's Great Lakes and St. Lawrence beaches are swimmable, however, sometimes some of them experience excessive bacteria levels that make the waters unsafe. Bacteria at beaches can come from a variety of sources, such as sewage and septic systems, waterfowl, and runoff from rural and urban areas. High bacteria levels are particularly a problem after heavy rains.

Excessive bacteria can pose a threat to human health and can cause sore throats, cold-like symptoms or diarrhea. Individuals with compromised immune systems, as well as young and old individuals, are more at risk from disease-causing bacteria in the water.

Beaches in Ontario are regularly tested for elevated bacteria levels. Limits are set on how much bacteria can be present at a beach before a warning is posted or the beach is completely closed to visitors.

Dam Construction and Water Diversions

Dam Construction and Water Diversions Dams, ponds and reservoirs have been constructed in the Great Lakes – St. Lawrence region for a variety of reasons including water supply, flood protection, power generation, and recreation. Dams and water diversions limit or change how rivers and streams are connected to the Great Lakes. Many native Great Lakes fish species require connections to streams and rivers, because they use both Great Lakes and stream habitat during their lifecycles. Streams and rivers provide important habitat for fish to spawn, act as nurseries for young fish, and offer protective habitat for fish during the winter. When natural connections between the Great Lakes and their tributaries are limited or removed, fish no longer have access to important habitat types and the number of fish, such as northern pike, may decline.

Tributaries, such as rivers and streams, also provide important water and nutrient inputs into the lakes. Preventing or changing the flow of these tributaries can change water quality by altering water and nutrient inputs into the Great Lakes. In particular, changing or diverting water negatively influences wetlands, which are the most productive habitats within the Great Lakes region.

Dredging

Dredging

In the Great Lakes and St. Lawrence River, dredging usually involves the removal of soil and mud from the bottom of waterways to maintain the required depth for safe operation of shipping vessels. Dredging also occurs to support waterfront development, utility placement, recreational boating, and environmental remediation. If done incorrectly, dredging can harm sensitive natural features and systems such as wetlands. It can lower the surrounding water table and impact adjacent wetlands as well as impact Great Lakes water levels and water quality.