[factoryrat]

What they won’t tell you is that the land around and under the great lakes is still “rebounding” from the weight of the glacial ice sheet that covered the region during the last ice age, roughly 12,000 years ago. Those same glaciers carved out the current great lakes, and then filled them with water.
So, the water level will always change, due to something we call “the weather”, and hope that Canada doesn’t call up Michigan, and tell them that they want their chunk of Ontario back, because that would be a whole lot of gravel to move.

[citizen]

Not sure what that last means “that [Canada] wants their chunk of Ontario back” but it sounds interesting. What’s the story there?

[palmer]

What they won't tell you is that the land around and under the great lakes is still "rebounding" from the weight of the glacial ice sheet that covered the region during the last ice age, roughly 12,000 years ago.

Quite true. The Great Lakes used to be part of glacial Lake Agassiz and most rivers north of Arkansas drained northward.