by JudyJB » Sun Dec 15, 2019 11:26 am
I am off to St. Augustine in a few minutes, but one last posting about Great Lakes water levels. (Water levels, by the way, do not affect just homeowners--they affect shipping of grain, iron ore, and other bulk stuff from the plains to the east and to international ports.)
First, think of the lakes as extremely big, deep, slow, and long rivers that are connected mostly with restraints of some sort. Lake Superior, for example, is connected with Lake Huron by the St. Mary's River, which used to have a bunch of rapids, but now also has the Soo Locks. Water enters the lake from the shores, especially the northern shores, and drains out to Lake Huron, but slowly because it is so deep with only a narrow river channel at its exit.
Lake Michigan is connected to Lake Huron at the Straits of Mackinac with a 4-5 mile wide channel. The two lakes have such a wide connection that they are often thought of as one lake. Lake Huron has some very deep spots but it empties into Lake Erie through the St. Clair River, Lake St. Clair, and the Detroit River. Outflow to Lake Erie is hampered by the rivers and by ice during the winter. Lake Erie is the shallowest of the five lakes, which is why it has always had a problem with pollution. It empties over Niagara Falls and through the Welland Canal into Lake Ontario, which is much deeper, although has about the same surface area. Once water gets to Lake Ontario, it heads east through the long and mostly-wide St. Lawrence Seaway.
Notice that while there are locks in a couple of places, there are really no huge human-built dams on this long navigable "river." So the water is not 100% controllable and varies with the seasons and the weather over long periods of time--some people say a 13 year cycle and others say it is much longer. But for ports with big ships coming in and out and homeowners along the shore, even two feet change in depth can cause real economic problems, which is why the Great Lake States and Canada have always fought anyone from taking the water from the lakes to ship it to Arizona or even bottle it!
