Low water levels on the Great Lakes

[Dave S]

I was just reading this article about Lake Superior in which they also mention the lower water levels in the other Great Lakes as well.

http://www.cnn.com/2007/TECH/science/08/03/superior.puzzle.ap/index.html

What kind of problems are low water levels causing for all you Great Lakes boaters?

 

[AndersonAcres]

I live in Iowa but grew up on the Great Lakes & have a geology background. I keep track of things there, and boat on N. Lake Michigan each year. This year we'll also be going to the North Channel of Lake Huron.

Here's a bit more info on those lake levels.

Lake Huron and Lake Michigan have the same water level.

Some manmade changes have lowered the level of the two, irrespective of precipitation. In the late 1800's the flow of the Chicago River was reversed. It now flows out of Lake MI eventually into the Mississippi and then the Gulf of Mexico. Thus, the Chicago river now subtracts slightly from the lake level, whereas it used to add to it slightly.

More damaging is the meddling with the outlet of Lake Huron at the St. Clair River. That's at the south end of Lake Huron. Also in the 1800's, the sand bars at that south end of Lake Huron were dredged. As a result, the levels of Lakes MI and Huron fell about a meter.

In the 1960's (I think) that area was again dredged resulting in even more water flowing from the two lakes. The increased flow from that dredging has resulted in continued erosion of the bottom and sides of the channel. More and more water flows out of those two lakes, dropping the lake levels. Those two lakes could end up at the same level as Lake Erie if the erosion isn't stopped.

Here's a reference: http://www.uswaternews.com/archives/arcsupply/5studblam2.html

Similarly, there was a ledge at the St. Mary's River that drains Lake Superior. That ledge has been lowered by man, and that's one factor contributing to the lower levels of Lake Superior. Of course lack of precipitation and warmer temperatures leading to increased evaporation are contributing factors, too.

Further reference:
http://www.lakelevels.org/LakeLevels.pdf

 

[goblue]

We just returned from a month long cruise of Lake Michigan and Lake Huron. The drop in water level is not noticable. Our slip is at our home in West Michigan on a lake that dumps into Lake Michigan. Again, not a real noticable difference in the slip. The lakes go up and down with the weather so there is variation every day. Seems like it is within the normal range for this time of the year.

 

[Gervie]

Here is a graph of the historic water levels of Lake Michigan/Lake Huron put out by NOAA.

 

[Cap10Pat]

With all the flooding this year they should be overflowing!

 

[AndersonAcres]

It's an interesting graph, isn't it?

If you look at the first dramatic drop, just after 1800, what you're seeing is the effect of the first dredging of the north end of the St. Claire River.

The low point of the graph, just after 1960, corresponds to the second dredging of that part of the St. Claire River. According to the researchers, that time was followed by high precipitation levels that masked the effect of the increased drainage through the St. Claire until around 2000 when the low levels were 'unmasked'.