We came across this paper on Lake Michigan Water Levels and thought it might clear up some of the confusion.
Lake Michigan is How High? How fast did it rise?
Two patently false statements were made in a public meeting recently. “Lake Michigan is the highest it has ever been” “Lake Michigan has gone up 4 feet this last year.” Both statements are patently false. The truth is actually more interesting and surprising.
Some quick background
Lake Michigan varies (on average) 10 inches from a January low to an August high every year. So if you are comparing years, you must specify a month of the year for it to be a true comparison. Except for December, 2012 and January 2013, the lowest recorded levels for the rest of the months of the year for Lake Michigan were in 1964. All of the highest levels for each month of the year were in 1986. The high and low years in the last cycle were 22 years apart. That would seem to predict a low in 2018. Not likely based on today’s levels.
Lake levels are mainly affected by rain (Lake Rises) and evaporation (Lake Drops). Ice on the water in the winter dramatically reduces evaporation and usually causes a rise in lake levels year over year. The fact that we had two winters (2013-14 and 2014-15) with loads of ice has likely contributed to the recent rapid rise in Lake Levels.
Erosion is affected by lake levels, but wind and wave action really cause erosion. The lake level just starts the waves from a higher point on the beach. Ice or lack of ice significantly impacts the effect of wind and waves on the beach. Ice stops wave action at the edge of the beach.
So here are April statistics for year over year comparisons (a good month because it is recent and it is something of an “average month”), April 1964 level was 576.16, the lowest on record; April 1986 level was: 581.46, the highest. That is a difference of 5.3 feet lowest to highest: which is quite a difference. But it took 22 years.
Now let’s look at the recent April stats from 2013 through 2016.
April 2013: 576.61
April 2014: 577.62
April 2015: 579.13
April 2016: 579.95
April, 2013 was only 0.45 feet (5.4 inches) higher than the lowest April on record in 1964. I find this interesting. The largest year to year jump in the past three years was from 2014 to 2015; up 1.51 feet. The difference between 2013 (a low year) and April 2016 is 3.34 feet. That 3-year change of 3.34 feet may be the fastest increase in Lake Michigan levels in history. I could not find a higher rate of change in my pile of USACE reports. Bears further study. But it has been a rapid change.
The last 12 months, Lake Michigan has only gone up 0.82 feet (about 10 inches; not much more than a normal yearly variation from January to August). But this last year has included a good number of days of high winds and large waves; especially from November, 2015 to May of 2016. During that year there was an almost complete lack of a protective winter ice on the shore.
Higher lake levels, frequent high winds and waves, and lack of ice protection in winter usually causes a lot of erosion. That is what we have witnessed this last year: Erosion; not rising water level.
The true, more interesting statements: “This past year we have had a lot of erosion.” “The 3.4 foot increase from April, 2013 to April, 2016 has been one of the most dramatic lake level increases in history.”
Courtesy of Dan Coffey