The Great Lakes are an important part of the world's freshwater system. It is normal for the Great Lakes to rise and fall depending on rain, snow, ice cover and evaporation.
Some people did not realize this when they built too close to the shoreline of one of these lakes. Their building tumbled into the water when the lake water rose.
The watersheds surrounding the five Great Lakes are small for the size of the lakes therefore it is important to keep their waters within their watersheds. Here is a link explaining why water should not be diverted: http://flowforwater.org/wp-content/uploads/2016/03/FINAL-FLOW-Press-Release-Waukesha-Diversion-3-1-2016.pdf Press-Release-Waukesha-Diversion-3-1-2016.pdf