The 96 years of measuring the water levels of the Great Lakes done by the Army Corps of Engineers represents a relative sliver of time compared to the thousands of years prior to 1918 when no one was keeping track of these levels. Nonetheless, in recent years global warming adherents were citing low water levels on the Great Lakes as evidence of global warming.
Now that Great Lakes levels are no longer low, they are seizing on the recent wet weather in southeast Michigan to advance their arguments.
The 4.7 inches of rain that swamped Detroit on Aug. 11 was the second highest daily rainfall for the city since the Army Corps of Engineers started keeping records in 1918. The highest daily rainfall on record for Detroit is 4.74 inches on July 31, 1925.
One difference between Detroit’s two heaviest rainfalls is that in 1925 the Great Lakes were heading toward a period of low water levels, but now in 2014, Great Lakes water levels appear to be headed upward.
“When the big rainfall took place in Detroit in 1925, the water levels on all of the Great Lakes were below average,” said Keith Kompoltowicz, chief of watershed hydrology for the Army Corps of Engineers in Detroit. “Great Lakes water levels fell to some of the lowest recorded levels in about 1926; but by 1930 they had pretty much rebounded.”
Kompoltowicz added that some low-water level marks continued to be set on Lake Erie and Lake Ontario into the mid-1930s.
In contrast to 1925, all of the Great Lakes, with the exception of Lake Michigan-Lake Huron, are now above the long-term monthly average for August. From a hydrological standpoint, Lake Michigan and Lake Huron are considered to be one lake. However, Lake St. Clair is considered as a separate lake, so there are still five lakes on which levels are measured in the Great Lakes system.
According to the Army Corps of Engineers, Lake Michigan-Huron is currently 15 inches above its level of last year and Lake Superior is nine inches higher than a year ago. Lake St. Clair is nine inches above a year ago and Lake Erie is three inches above last year. Lake Ontario is an inch lower than last year’s level.
Amid claims in the early 2000s that Great Lakes water levels were dropping due to global warming, Todd Thompson, an expert on Lake Michigan-Huron water levels with the Indiana Geological Survey, argued that the levels were not out of sync from a historical perspective. In the April 7, 2003, edition of the MIRS newsletter, he said he expected the lakes to return to more “average” levels within 10 years — this prediction proved to be only one year off.
Thompson had done extensive research on sediments around the Lake Michigan-Huron shorelines and created graphs that he said represented natural high- and low-water level cycles going back more than 4,000 years — to the point when a western outlet dried up and the modern Great Lakes system was born. In 2003, Thompson also said he believed the lake levels would be on the high side by 2016.
After having set two monthly low-level records (for the period over which measurements have been taken) just a year and a half ago, Lake Michigan-Huron is now only three inches below the long-term average for August. It is 28 inches above its level of 1964, which was its lowest level recorded for August. It is 36 inches below its 1986 level, which was its highest recorded level for August.
Lake Superior is six inches above the long-term average, only seven inches below its highest recorded August level, which was measured in 1952, and 26 inches above its lowest recorded August level, which was measured in 2007.
Lake St. Clair is four inches above the long-term average, 25 inches below its highest recorded August level, which was measured in 1986, and 33 inches above its lowest recorded August level, which was measured in 1934.
Lake Erie is five inches above the long-term average, 22 inches below its highest recorded August level, which was measured in 1986, and 37 inches above its lowest recorded August level, which was measured in 1934.
Lake Ontario is six inches above the long-term average, 22 inches below its highest recorded August level, which was measured in 1947, and 40 inches above its lowest recorded August level, which was measured in 1934.