Great Lakes Water Levels

Bill's Blog

Sunset on Bois Blanc Island – pic. by Bill Steffen

I took the pic. above on Bois Blanc Island back in July. Note that the water comes right up to the tree on the right – there essentially was no beach there where the picture was taken.

Lake Superior is unchanged in the last month, down 3″ in the last year and is now 10″ higher than average. The lake is 3″ below the highest August average level set last year.

Lake Michigan/Huron (one lake for lake level purposes) is down 2″ in the last month, but up 4″ in the last year. The lake(s) is 33″ above the August water level and is now 1″ higher than the August highest average set in 1986.

Lake Erie is down 6″ in the last month, down 5″ in the last year and is now 25″ above the August average level. The lake is 5″ below the August record high average level set in 2019

Lake Ontario is also down 6″ in the last month and down a whopping 18″ in the last year. The lake is only 5″ above the August average level and is 22″ below the highest August average level set in 1947.

Lake St. Clair is down 3″ in the last month, unchanged in the last year and is now 31″ above the average August water level. The lake is even with the highest average August level set in 2019.

Here’s Great Lakes water levels since 1918

Here’s a graph of Great Lakes water levels since 1918. The main determining factor for lake levels is precipitation. Grand Rapids set a record high 5-year precipitation total from 2015-2019.

International Bridge August 21, 2020

The rivers that connect the Great Lakes have above to well-above average flow. The St. Mary’s River had a flow of 82,600 cfs Fri. PM. The St. Clair River at Port Huron has a flow of 261,000 cfs compared to an average flow of 191,000 cfs. That’s 137% of average flow.

Grand River in Grand Rapids from Riverhouse

Most rivers have slowly falling water levels, but many remain above average flow. The Grand River in Grand Rapids has a flow of 1,870 cfs, compared to an average flow of 1,590 cfs (117% of average). The Muskegon River at Croton has a flow of 1,100 cfs, compared to an average flow of 1,160 cfs. That’s 95% of average flow. The Kalamazoo River at Comstock has a flow of 616 cfs, compared to an average flow of 560 cfs. That’s 110% of average flow. The Saginaw River at Saginaw has a flow of 2,250 cfs, compared to an average flow of 1,600 cfs. That’s 140% of average flow. The Fox River at Appleton, Wisconsin has a flow of 2,130 cfs, compared to an average flow of 1,810 cfs. That’s 116% of average flow.

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