Consensus: CO2 allegedly causes low Lake Superior water levels, with exceptions like during the late 1960s through 1999, water levels were above average, and also water levels jumped more last month than all but one other month since 1918?

2007: Shrinking Lake Superior Also Heating Up

From the late 1960s to 1999, there was a 30-year period with water levels above average, said Scott Thieme, chief of the Great Lakes Hydraulics and Hydrology Office for the U.S. Army Corps of Engineers in Detroit, Michigan. But in 1999, the upper lakes started to fall below average and have mostly stayed that way.

Now:  Lake Superior level rises quickly in May - TwinCities.com

The water level of Lake Superior jumped 9 inches in May, more than twice the normal monthly increase and the second most for any month since 1918.
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The big lake now sits just 7 inches below its long-term average for June 1. It is a full 3 inches above the level at this time last year, the International Lake Superior Board of Control reported Friday.