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Great Minds, Great Lakes


Social Studies

The Journey of the Great Lakes



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The End of the Journey, Lake Ontario!

Lake Guardian was nervous as she left Lake Erie, for she thought that she might take a wrong turn and go over Niagara Falls! She was big and strong, but no boat could survive a ride like that. She was relieved to find the Welland Canal and make here way to beautiful Lake Ontario. She had heard so much about the falls, and the breathtaking Thousand Islands on the east end.

Lake Guardian got out her map to trace her journey. She was very interested in looking at how all the water in the Lakes eventually comes through Lake Ontario because it is the last Lake before that water heads out the St. Lawrence River and into the ocean. This means that a lot of the dissolved substances and pollution she studied in the other Great Lakes also has journeyed to Lake Ontario, which is one of the reasons why Lake Ontario is the most polluted of all the Great Lakes. Lake Guardian knew that another reason was its small size. It doesn't have as much water to spread out the pollution.

Lake Guardian traveled first by Hamilton and Toronto, Canada, passing lots of big industrial factories and buildings. She remembered all the factories and big machines she had seen along the shores of all the other Great Lakes. Lake Guardian was concerned about more than the smokestacks and air pollution she had learned about. She was worried about chemicals dumped by the factories and businesses into the water. Lake Guardian thought about Herring Gull's friends the cormorants, and what she learned in Lake Michigan about the chemicals from farms running off into the water and settling to the bottom for small creature to eat. She knew that this was happening with he chemicals from factories and businesses too.

She asked Dave, the environmental scientist, if there were other effects from these chemicals on the Great Lakes besides polluting sediments and entering the food chain. Dave described how some chemicals, such as nitrogen and potassium, from industry, farms, and city areas are like food to green plants in the water, including algae. "The algae grow very gig very fast, and we call it an algae bloom. It eventually dies," Dave explained, "but when it does, the bacteria that feeds on the dead algae takes a lot of the water's oxygen. The more algae that blooms and dies, the more bacteria there is taking oxygen from the water." Lake Guardian knew that without oxygen, many species of fish could not live. Dave explained that when a lake's oxygen levels are lowered, some species die out--mayflies included-and others like sludge worms and carp, that can tolerate low levels of oxygen move in. That's why scientist look for changes in the kinds of animals living in the Great Lakes. It tells them if too many chemicals are changing oxygen levels and upsetting the balance of animals and nature, called the ecosystem.

Lake Guardian got to work and collected samples and looked for algae blooms all along the shoreline of Lake Ontario. She examined the different species to see if she could tell if chemicals were changing the water's oxygen levels too much.

By the end of the journey, Lake Guardian had learned a lot about the beautiful Great Lakes. She wanted to tell everyone about all that she had learned. What could people do to help the Great Lakes? She was concerned about the many pollution problems that she saw, but she know that things could get better. Lake Guardian knew that by helping to collect samples and learning more about the Lakes, she was part of the solution. That made her feel proud as she journeyed up the St. Lawrence River to peek at the ocean before heading back home.


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