"The Great Lakes were pretty much a closed eco-system for thousands of years. The plants, animals and fish within this system co-existed with one another in a relatively balanced level. The early arrival of explorers from the east had little impact on this balance. The arrival of settlers in greater and greater numbers began to change the landscape. Logging and farming re-shaped the lands around the rivers and streams feeding into the lakes. As the human population grew, the once-balanced environment became unbalanced."
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